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Landscape Message: June 9, 2023

Landscape Message: June 9, 2023
June 9, 2023

UMass Extension's Landscape Message is an educational newsletter intended to inform and guide Massachusetts Green Industry professionals in the management of our collective landscape. Detailed reports from scouts and Extension specialists on growing conditions, pest activity, and cultural practices for the management of woody ornamentals, trees, and turf are regular features. The following issue has been updated to provide timely management information and the latest regional news and environmental data.

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To read individual sections of the message, click on the section headings below to expand the content:

Scouting Information by Region

Environmental Data

The following data was collected on or about June 7, 2023. Total accumulated growing degree days (GDD) represent the heating units above a 50ºF baseline temperature collected via regional NEWA stations ( for the 2023 calendar year. This information is intended for use as a guide for monitoring the developmental stages of pests in your location and planning management strategies accordingly.

MA Region/Location

2023 Growing Degree Days

Soil Temp
(°F at 4" depth)

(Gain in inches since last report)

Time/Date of Readings

Gain since last report

2023 total









6/7/2023 12:00 PM







6/7/2023 2:30 PM







6/7/2023 9:30 AM







6/7/2023 4:00 PM







6/7/2023 5:30 AM







6/7/2023 3:00 PM







6/7/2023 11:30 AM







6/7/2023 6:00 AM








n/a = information not available


US Drought Monitor:  The Cape and the islands, as well as parts of Southeastern MA, and most of western Berkshire county (approximately 20% of the total area of Massachusetts) are classified as "D0: Abnormally Dry" as of Thursday 6/8:


Indicator Plants - Stages of Flowering (BEGIN, BEGIN/FULL, FULL, FULL/END, END)
Catalpa speciosa (Northern catalpa) * * * * * * * Begin
Sambucus canadensis (American elderberry) * Begin Begin Begin/Full Begin Begin Begin *
Kalmia latifolia (mountain laurel) Begin Full Begin/Full Full Full Full Full Full
Cotinus coggygria (common smokebush) Begin/Full Full Full Full Full Full Full Buds frost killed
Weigela florida (old fashioned weigela) Full Full/end Full Full Full Full Full Full
Robinia pseudoacacia (black locust) Full End Full/End End Full/End Full/End End *
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions:

The average temperature for the period from May 31 thru June 7 was 58ºF with a high of 79ºF on June 2nd and a low of 46ºF on June 4th. The period started warm and then cooled significantly; June 3-5 had highs only in the mid 50s. June 3-7 was mostly cloudy with significant air quality impacts from the wildfires in Canada. Precipitation did occur on several days during the period, however accumulation totals were less than a quarter inch. The cool, cloudy and light precipitation during the period did ease water stress temporarily, however soils are still dry.

Herbaceous plants in bloom during the period include bearded iris (Iris x germanica), lupine (Lupinus spp.), catmint (Nepeta spp.), columbine (Aquilegia spp.), and peony (Paeonia spp.). Woody plants in bloom include Catawba rhododendron and black locust which are just past full bloom, kousa dogwood (Cornus kousa), yellowwood (Cladrastis kentukea), tuliptree (Liriodendron tulipifera), and viburnum (Viburnum dentatum & V. nudum).


Cankerworm and winter moth caterpillars are done feeding at this time and only light damage (holes in leaves) has been observed. Spongy moth caterpillars continue to feed and damage can be seen in some areas of the Cape (not widespread); and may result in some light defoliation in those areas. Other insect or insect related damage observed during the period includes sawfly larvae feeding on oak, eastern tent caterpillar feeding on black cherry, black turpentine beetle activity on pitch pine, viburnum leaf beetle larvae feeding on arrowwood, dogwood sawfly feeding on alternate leaf dogwood, rose slug sawfly larvae feeding on rose, whitefly on Japanese holly, willow leaf beetle feeding on willow, boxwood psyllid on boxwood, elder shoot borer damage on elderberry, white pine aphid feeding on white pine, oak vein pocket gall midge damage on oak, some flagging as a result of gall wasp damage on black oak, and aphids on various herbaceous and woody plants. 

Beech leaf disease has been observed widely on the Cape on both American beech forest stands as well as ornamental European beech. Some trees have experienced relatively dramatic bud damage resulting in little foliage, though new foliage is starting to be pushed out. Other disease symptoms or signs observed during the period include apple scab on crabapple, brown rot on ‘Kwanzan’ cherry, sycamore anthracnose on sycamore, exobasidium gall on azalea and blueberry, venturia leaf and shoot blight on poplar, nectria canker on mimosa and sclerotinia stem rot on aster. White pine foliage is looking extremely thin on some white pines as a result of white pine needle disease. Excessive needle loss has been observed on yew.

The dead stems of bigleaf hydrangea, roses and butterfly bush are still common sights in the landscape. Cleanup of dead stems should be done now. Damage from last season’s drought is also readily visible, particularly with dieback on rhododendron and failure of unestablished plants, particularly arborvitae. The current lack of soil moisture is also contributing to failures of recent transplants. Extra attention to supplemental watering of unestablished plant material is needed, with a reminder that establishment can take several years for woody plants. Some unirrigated lawns are already showing signs of the lack of soil moisture, compounding issues from the previous season.   

Weeds in bloom include multiflora rose (Rosa multiflora), Asian bittersweet (Celastrus orbiculatus), common cinquefoil (Potentilla simplex), cats ear (Hypochaeris radicata), black medic (Medicago lupulina), white clover (Trifolium repens), yellow wood sorrel (Oxalis stricta), sheep sorrel (Rumex acetosella), narrowleaf plantain (Plantago lanceolata), and buttercup (Ranunuculus bulbosus).

Catsear in bloom (R. Norton) Nectria canker sporulation on mimosa (R. Norton) Oak vein pocket gall midge damage on oak (R. Norton) Rose slug sawfly larvae on rose (R. Norton) Sclerotinia stem rot damage on aster (R. Norton) Sclerotinia stem rot on aster (R. Norton) Spongy moth caterpillars feeding on oak (R. Norton) Venturia leaf blight on poplar (R. Norton) Venturia leaf blight on poplar 2 (R. Norton) Viburnum leaf beetle damage on V. dentatum (R. Norton) Viburnum leaf beetle larvae (R. Norton)

Southeast Region (Dighton)

General Conditions:

The temperatures over the first week of June have been pleasant, but general conditions were marred by poor air quality and the lack of significant rainfall. The high temperature was on Saturday, June 3rd, at 81°F. The low was 43°F on Monday morning June 5th. The average temperature for the week was 55°F. Occasional overcast, haze, smoke and light showers arrived on Sunday, then persisted through the remainder of the week with little to show for it at 0.35 inches of preciptation measured. The highest winds were on Saturday at 21 mph.

Plants in flower: Enkianthus campanulas, Deutzia, Cotinus coggygria (smoke bush), Kalmia latifolia (mountain laurel), Sambucus canadensis (American black elderberry), Rhododendron catawbiense (Rosebay hybrids), Syringa meyeri (Meyer lilac), Weigela florida.


The air quality over the past week has been abysmal. Pollen counts are still quite high. On Saturday morning, smoke and haze from Canadian wildfires arrived. Although we've had passing clouds and overcast, precipitation has been disappointing. According to the US drought monitor NOAA/NCEI, all of Plymouth County and the southeast corner of Bristol County are abnormally dry. Drought stress is already apparent on unirrigated turf with southern exposures. Irrigation bans are in effect in some towns, limiting irrigation to hand watering. Clients are complaining about mosquitos and ticks. 

North Shore (Beverly)

General Conditions:

The first two days of this reporting period were very warm with day temperatures in the mid 80s and night temperatures in the low 50s. A cold front moved into the area on June 3 and brought cooler temperatures and rain showers. The weather in the last five days was mostly cloudy and overcast with occasional rain showers. Approximately 0.65 inches of rain was recorded at Long Hill. Temperatures were unseasonably cool for this time of the year, feeling like early spring rather than the unofficial start of summer. Day temperatures ranged from the mid 50s to low 60s and night temperatures ranged from the high 40s to low 50s. The average daily temperature was 59℉ with the maximum temperature of 86℉ recorded on June 2 and a minimum temperature of 44℉ recorded on June 4. Woody plants seen in bloom include: Kousa dogwood (Cornus kousa), arrowwood viburnum (Viburnum dentatum), fringe tree (Chionanthus virginicus), mock orange (Philadelphus spp.), beautybush (Linnaea amabilis), mountain laurel (Kalmia latifolia), weigela (Weigela florida), Korean dogwood (Cornus coreana), stiff dogwood (Cornus foemina), maple leaf viburnum (Viburnum acerifolium), yellowwood (Cladrastis kentukea), deutzia (Deutzia crenata), Chinese neillia (Neillia sinensis), and ninebark (Physocarpus opulifolius). Non-woody plants seen in bloom include: catmint (Nepeta spp.), salvia (Salvia spp), foam flower (Tiarella cordifolia), leopard's bane (Doronicum spp.), goat’s beard (Aruncus dioicus), fetterbush (Leucothoe fontanesiana), peony (Paeonia sp.), Rodger's flower (Rodgersia aesculifolia), Japanese primrose (Primula japonica), columbine (Aquilegia spp.), sweet woodruff (Galium odoratum), amsonia (Amsonia hubrichtii) and annuals such as petunia and million bells.


Leaf and flower galls (Exobasidium vaccinii) on azalea and rhododendron continue to enlarge and become white with spores. Prune out the galls and discard in the trash (not compost) before they release their spores. Skeletonized leaf damage by Viburnum leaf beetle larvae was observed on American cranberrybush viburnum (Viburnum opulus var. americanum), but the damage is much less compared to last year. Apple scab (Venturia inaequalis) was observed on crabapple trees. Multiflora rose (Rosa multiflora) and wild raspberry (Rubus rosifolius) weeds are in bloom and are easy to identify. Ticks and mosquitoes are very active. Make sure to protect yourself with appropriate repellants before going out into areas with vegetation, especially out in the woods.

Exobasidium leaf and flower gall on Rhododendron Powdery mildew on Monarda

East (Boston)

General Conditions:

We experienced drastic temperature fluctuations over the past week. June first and second reached 91ºF and 90ºF respectively, followed by three days in the fifties with a daytime low of 53ºF on June fourth. Overnight lows were consistent, averaging 50ºF over the seven day reporting period. Our consecutive streak of eight days with no precipitation was broken on June second when we received 0.64 inches. We continued to receive intermittent precipitation over four days totaling .94 inches. Plants in bloom include: Amsonia hubrichtii (Hubricht’s bluestar), Calycanthus floridus (sweetshrub), and Cladrastis kentukea (American yellowwood).


Plants slow to leaf out this spring are pushing out new growth. Branch dieback in ornamental trees and shrubs is becoming more apparent.

Metro West (Acton)

General Conditions:

We experienced some summer-like weather late last week with temperatures into the 90s, then the temperatures dropped significantly into the 50s over the weekend and into the earlier part of this week. There were two days when temperatures were recorded into the 90s - 91°F on the 1st and 93°F on the 2nd - the highs for the week. The heat was driven away with a rain event that same day that brought with it 1.11” of rain. A low of 46°F was recorded on the 4th. The average monthly rainfall for June is 3.93” and 1.33” was recorded for this area so far this month. 


New foliage is pushing out on plants previously reported as damaged by freezing temperatures in May. These include Catalpa, Celastrus orbiculatus (Oriental bittersweet), Fagus (beech), and Quercus (oak). Due to the wildfires in Canada, the air quality was poor and there was a faint smell of burning wood in the air on the 6th.

Central Region (Boylston)

General Conditions:

This reporting period was punctuated by wild temperature swings, promises of precipitation that didn’t pan out, and some crazy sunsets thanks to wildfire smoke from Canada. The week started with the typical early summer temperature patterns we expect to see in late May and early June, but colder temperatures from the north moved in with some mild thunderstorms on Friday, June 2. The remainder of the reporting period was unseasonably cool, damp, and dark. Air quality has been bad, with warnings to sensitive groups to stay indoors and avoid strenuous outdoor activity due to the heavy wildfire smoke and airborne particulate matter. In spite of the odd weather, the landscape feels lush and colorful with plenty in bloom, including a relatively uncommon wetland species called false hellebore (Veratrum viride). Normally spotted growing alongside skunk cabbage (Symplocarpus foetidus), false hellebore has tall flower spikes that are more interesting than showy, but quite attractive to a wide array of pollinators.


We are still seeing signs of impact from the late season frost/freeze we experienced in mid-May and the deep freeze we experienced in early February. Among others, Japanese scholar tree (Styphnolobium japonicum) experienced substantial dieback. Weeping cherries (Prunus × subhirtella ‘Pendula’) are finally leafing out. Many invasive plant species are in bloom across the regon, including dame’s rocket (Hesperis matronalis). 

Pioneer Valley (Amherst)

General Conditions:

This reporting period had it all in the Pioneer Valley with heat (temperatures ≥90°F on 6/1 and 6/2), powerful, fast-moving thunderstorms (6/2 & 6/6), persistent gusty winds, poor air quality from the Canadian wildfires (6/6 & 6/7), mild and pleasant conditions, and cool nights dropping down in the 40s. While May was primarily sunny and warm with ultra-low humidity (aside from the first week), June has started off cool and cloudy. The return to seasonable temperatures has been a bit jarring after the warm May but the heat will undoubtedly return soon to the region. This past week has been a good respite for plants as tender new growth continues to develop and harden off. Rainfall from the two bands of thunderstorms was variable and mostly unimpressive, with totals ranging from 0.2″ (South Deerfield), 0.35″ (Westfield), 0.59″ (Belchertown), and 0.61″ (Ashfield). There were pockets of accumulations >1″ but that was not widespread through the tri-counties. Despite the lackluster totals, the dramatic drop in temperatures and persistent cloud cover has helped retain soil moisture and irrigation intervals can now be lengthened accordingly. The fallout from the 5/18 frost continues with a wide assortment of leaf and shoot distortion on display right now. In the immediate aftermath, it was easy to identify plants with burned shoots and leaves, but the more nuanced injury has revealed itself at a slower pace. Prior to the cool down on 6/3, turfgrass on well-drained soils was starting to brown out in locations but has been rejuvenated a bit since. Mosquitoes and black flies continue to be a major nuisance. Kousa dogwoods, mountain laurels, peonies and Japanese tree lilacs are in full bloom. 


Symptoms of white pine needle blight are peaking across the region. Throughout the canopy of infected white pines, older, brown needles are shedding rapidly while new needles continue to develop. Because the current season’s growth is only partially formed, trees can look extremely thin once most of the older needles are shed. Needle shedding coincides with peak sporulation and spread by the needle blight pathogens responsible. The newly developing needles are very susceptible to infection right now, but typically do not show symptoms of the disease for many months, up to one year after infection. Septorioides strobi is one of the most prominent pathogens on white pines in southern New England. Foliar anthracnose on sycamore, beech, maple and oak is common right now. Some injury from the oak shothole leafminer was observed on red and black oak. There was a widespread outbreak of this native pest five years ago and since that time, isolated pockets of injury have been observed. Burned, blighted, and distorted shoots and leaves on trees and shrubs from the May 18 frost are scattered across the landscape. For smaller trees and shrubs, pruning out the blighted leaves themselves (not the stems) can improve aesthetics and reduce the risk of colonization by opportunistic pathogens. For many rhododendrons and azaleas that did not flower due to the freeze event in early February, vegetative growth appears to be strong and there does not appear to be any significant injury beyond the loss of the flowers. Many flowering cherries continue to improve in appearance as new growth very slowly develops throughout the canopy. While cherries are improving, some have significant twig dieback and these dead stems should be pruned out as soon as possible. However, if any shoots show signs of new growth, it would be best to wait for several more weeks to determine how well this new growth emerges. The return to cooler temperatures should help these trees.

Berkshire Region (West Stockbridge)

General conditions:

After high temperatures in the upper 80s at the beginning of the current scouting period, a significant cool down developed. High temperatures were 90°F in North Adams on June 1 and in Pittsfield on June 2. The Richmond site recorded 88°F on June 2. Rainfall amounts varied considerably from the upper end of the Berkshires, i.e. North Adams, to the southern border at the Connecticut state line. North Adams' total was 1.32 inches with 1.18 inches occurring on June 2. Totals for other NEWA sites were 0.66 inches in Pittsfield and 0.69 inches at Richmond. This site in West Stockbridge collected only 0.46 inches. The rain was welcomed at all sites as soils had been quite dry. Turfgrass growth has slowed a bit in those areas that received little rain over the past month.


Spongy moth caterpillars are still feeding on the foliage of trees and shrubs. However, most of the damage has been limited to holes in leaves of infested trees and shrubs. No serious defoliation has yet been observed. The caterpillars range in size from about ¼ inch to a little over an inch, rather small for their normal stage of development at this time. It seems that their development has been very slow. Also, there have been many sightings of dead and shriveled caterpillars. This could be an indication of infection by the Entomophaga maimaiga fungus or the nucleopolyhedrosis (NPV) virus. Spittlebugs have made their appearance and can be found on both annuals and herbaceous perennials. So far, they seem to have had no effect on the health of the infested plants. Cyclamen mites are causing much damage to the flower buds of delphinium. Other pests observed were: cutworms, lily leaf beetle adults, and aphids on a variety of plant materials. Perhaps due to a rather dry spring thus far, plant diseases have been few. Leaf spots on maples and apple scab were observed this week. There are still many plants with browned and wilted leaves as well as damaged flower buds and some twig death that resulted from the severe hard frost of May 18th. Among the most damaged were smokebush (Cotinus coggygria), copper beech (Fagus sylvatica f. purpurea), magnolias, and Japanese maple (Acer palmatum). The prolonged dry period has also affected the health of some shrubs. These were typically un-irrigated, un-mulched, and located on slopes. Also affected by the lack of rain are lawns, as indicated by browned turf.

Aphids on Helianthus (photo by Jennifer Kujawski)

Regional Scouting Credits

  • CAPE COD REGION - Russell Norton, Horticulture and Agriculture Educator with Cape Cod Cooperative Extension, reporting from Barnstable.
  • SOUTHEAST REGION - Brian McMahon, Arborist, reporting from the Dighton area.
  • NORTH SHORE REGION - Geoffrey Njue, Green Industry Specialist, UMass Extension, reporting from the Long Hill Reservation, Beverly.
  • EAST REGION - Kit Ganshaw & Sue Pfeiffer, Horticulturists reporting from the Boston area.
  • METRO WEST REGION – Julie Coop, Forester, Massachusetts Department of Conservation & Recreation, reporting from Acton.
  • CENTRAL REGION - Mark Richardson, Director of Horticulture reporting from New England Botanic Garden at Tower Hill, Boylston.
  • PIONEER VALLEY REGION - Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, reporting from Amherst.
  • BERKSHIRE REGION - Ron Kujawski, Horticultural Consultant, reporting from Great Barrington.

Woody Ornamentals


Recent pests, pathogens, or problems of interest seen in the UMass Extension Plant Diagnostic Lab, a select few:

Beech leaf disease (Litylenchus crenatae ssp. mccanii) and beech anthracnose (Apiognomonia errabunda) on American beech (Fagus grandifolia). Two trees in a managed woodland setting that are approximately 10- to 15-years-old and receive a mixture of sun and shade. In addition to the typical symptoms of BLD (dark green, interveinal banding with convex cupping when the leaf surface is viewed from above), there were also brown blotches typical of anthracnose. Upon closer inspection, beech anthracnose was present on the interveinal bands created by BLD, but were absent from healthy interveinal regions on the same leaf. While this is an anecdotal observation, it appeared that areas of the foliage injured by BLD were more susceptible to beech anthracnose. Anthracnose diseases have been abundant this season, owing to the good conditions for disease development in late April and early May.   

Sunscald on a Snake Eyes Japanese white pine (Pinus parviflora 'Ogon-janome'). The tree is approximately 20-years-old and has been in its present location for 12 years. 'Ogon-janome' is a shrub-like cultivar with intermediate growth rates and has yellow variegation on the needles. It receives full sun and shade in well-drained, loam-based soils with drip irrigation. For several years now, the new growth emerges normally but then takes on a brown, unhealthy discoloration. The tree was believed to be a Pinus densiflora 'Oculus-draconis' (Dragon’s eye Japanese red pine). However, Japanese red pine has two needles per fascicle while Japanese white pine has five. Additionally, Japanese red pine needles are generally much longer, depending on the specific cultivar. Pinus parviflora 'Ogon-janome' can be very susceptible to sunburn and is likely receiving too much direct sunlight. The tree can thrive in bright shade and will likely need to be moved to a more protected location to avoid injury in the future.

Winter injury and Botryosphaeria stem cankering on a saucer magnolia (Magnolia × soulangeana). The tree is approximately 8- to 10-years-old and has been present at the site for five years. It resides in a residential lawn with full sun, surrounded by a very small mulch ring among an expanse of lawn. Some irrigation is provided by lawn sprinklers. After bud break this spring, new growth began wilting and the canopy appeared very thin. Submitted stems had blackened bark with brown vascular tissue underneath. After a short incubation, Botryosphaeria was abundant on the symptomatic material. Heat and drought stress could have predisposed the tree in previous years, allowing Botryosphaeria to establish and spread.

Marginal leaf blight, caused by Colletotrichum, on Greenspire little leaf linden (Tilia cordata 'Greenspire'). Three trees are symptomatic out of 20 total, which were planted along both sides of a road five years ago. These 10-year-old trees reside in full sun with sandy-loam soils and have been hand-watered during dry periods since they were transplanted. In early May, a marginal leaf blight developed throughout the canopy and the symptomatic foliage is undersized compared to neighboring, healthy trees. There was no evidence of any stem cankering or vascular wilt diseases and the injury appears to be on the foliage alone. Colletotrichum was present throughout the blighted leaf margins and will continue to expand during mild and wet conditions during the growing season.

Report by Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, UMass Amherst.

Insects and Other Arthropods

Interesting Insects Reported or Seen Recently:

  • The black cherry aphid (Myzus cerasi) photographed on fruiting cherry in Berkshire County, MA on 6/5/2023. (Photo courtesy of: Tom Ingersoll.) Black Cherry Aphid: Myzus cerasi is currently the only black colored aphid on Prunus (Prunus cerasus and P. avium). Adults are approximately 0.125 inches long and use piercing-sucking mouthparts to feed on cherry foliage. The black cherry aphid was reported from fruiting cherry in Berkshire County, MA on 6/5/2023 (photo courtesy of Tom Ingersoll). These aphids overwinter as eggs laid in the cracks and crevices of host plant bark or twigs. Eggs are tiny and a shiny black. Egg hatch occurs as spring temperatures warm and feeding begins on unopened buds and host plant leaf undersides. Nymphs are amber to various shades of dark brown to black as they develop. As a result of their feeding, cherry leaves may become curled with reduced terminal growth. Curled leaves protect the aphids feeding within. Honeydew or liquid sugary excrement is also deposited on the leaves of the host plant by these insects. Ants tend the aphids, feeding on their honeydew. Older, established trees can typically withstand the feeding activities of the black cherry aphid, however in production agriculture the damage to young trees may be significant to their overall health. Two or three generations may occur, after which a winged sexual form migrates to alternative hosts in the summer (weeds, ornamentals, vegetables, and plants in the mustard family) to mate and bear subsequent generations. By the fall, the winged form returns to Prunus spp. hosts to deposit the overwintering eggs. Aphids have many natural enemies, which can help reduce damaging populations, such as but not limited to: lacewings, lady beetles, and syrphid flies. Take care with chemical management options to avoid potential negative impacts to natural enemies. If practical, these aphids can be syringed from the host plant with a strong jet of water from a hose. This can remove the aphids from the host without the use of chemicals. Avoid fertilizing trees infested with aphids, as this may provide more food not only for the plant but also for the insects.

Current Nuisance Problems of Note:

Anyone working in the yard and garden should be aware that there is the potential to encounter deer ticks. The deer tick or blacklegged tick can transmit Lyme disease, human babesiosis, human anaplasmosis, and other diseases. Preventative activities, such as daily tick checks, wearing appropriate clothing, and permethrin treatments for clothing (according to label instructions) can aid in reducing the risk that a tick will become attached to your body. If a tick cannot attach and feed, it will not transmit disease. For more information about personal protective measures, visit:

The Center for Agriculture, Food, and the Environment provides a list of potential tick identification and testing resources here: .

*In the news: UMass Amherst has now been designated as the location for the New England Center of Excellence in Vector-Borne Diseases (NEWVEC). This CDC (Centers for Disease Control and Prevention) funded center will work to reduce the risk of vector-borne diseases spread by ticks, mosquitoes, and other blood-sucking insects or insect relatives in New England: . For more information and to contact NEWVEC, visit: To contact the center for more information about their Spring 2023 Project ITCH (“Is Tick Control Helping”), visit: .

Note: Dog ticks (Dermacentor variabilis) continue to be noticeably active in parts of Berkshire and Hampshire County in 2023. They are present in large numbers this year even in environments where tick activity is typically low, such as in mowed lawns.

  • Mosquitoes: According to the Massachusetts Bureau of Infectious Disease and Laboratory Science and the Department of Public Health, there are at least 51 different species of mosquito found in Massachusetts. Mosquitoes belong to the Order Diptera (true flies) and the Family Culicidae (mosquitoes). As such, they undergo complete metamorphosis, and possess four major life stages: egg, larva, pupa, and adult. Adult mosquitoes are the only stage that flies and many female mosquitoes only live for 2 weeks (although the life cycle and timing will depend upon the species). Only female mosquitoes bite to take a blood meal, and this is so they can make eggs. Mosquitoes need water to lay their eggs in, so they are often found in wet or damp locations and around plants. Different species prefer different habitats. It is possible to be bitten by a mosquito at any time of the day, and again timing depends upon the species. Many are particularly active from just before dusk, through the night, and until dawn. Mosquito bites are not only itchy and annoying, but they can be associated with greater health risks. Certain mosquitoes vector pathogens that cause diseases such as West Nile virus (WNV) and eastern equine encephalitis (EEE).

For more information about mosquitoes in Massachusetts, visit:

EEE and WNV testing and tracking for this season will begin on June 12, 2023. The Massachusetts Department of Public Health tracks animal cases, human cases, and mosquito positive samples from traps from June through October in Massachusetts. No cases or positive samples have been reported as of June 5, 2023. More information can be found here:

There are ways to protect yourself against mosquitoes, including wearing long-sleeved shirts and long pants, keeping mosquitoes outside by using tight-fitting window and door screens, and using insect repellents as directed. Products containing the active ingredients DEET, permethrin, IR3535, picaridin, and oil of lemon eucalyptus provide protection against mosquitoes. Be aware that not all of these can be safely used on young children. Read and follow all label instructions for safety and proper use.

For more information about mosquito repellents, visit: and

  • Wasps/Hornets: Many wasps are predators of other arthropods, including pest insects such as certain caterpillars that feed on trees and shrubs. Adult wasps hunt prey and bring it back to their nest where young are being reared, as food for the immature wasps. A common such example are the paper wasps (Polistes spp.) who rear their young on chewed up insects. They may be seen searching plants for caterpillars and other soft-bodied larvae to feed their young. Paper wasps can sting, and will defend their nests, which are open-celled paper nests that are not covered with a papery “envelope”. These open-celled nests may be seen hanging from eaves or other outdoor building structures. Aerial yellow jackets and hornets create large aerial nests that are covered with a papery shell or “envelope”. Common yellow jacket species include those in the genus Vespula. Dolichovespula maculata is commonly known as the baldfaced hornet, although it is not a true hornet. The European hornet (Vespa crabro) is three times the size of a yellow jacket and may be confused for the northern* giant hornet (Vespa mandarinia). The European hornet is known to Massachusetts, but the northern giant hornet is not. If you are concerned that you have found or photographed a northern giant hornet, please report it here: Paper wasps and aerial yellowjackets overwinter as fertilized females (queens) and a single female produces a new nest annually in the late spring. Queens start new nests, lay eggs, and rear new wasps to assist in colony/nest development.Nests are abandoned at the end of the season. Some people are allergic to stinging insects, so care should be taken around wasp/hornet nests. Unlike the European honeybee (Apis mellifera), wasps and hornets do not have barbed stingers, and therefore can sting repeatedly when defending their nests. It is best to avoid them, and if that cannot be done and assistance is needed to remove them, consult a professional.

*For more information about the common name change for Vespa mandarinia, please visit:

Woody ornamental insect and non-insect arthropod pests to consider, a selected few:

Highlighted Invasive Insects & Other Organisms Update:

  • Spongy moth egg mass and tiny, newly hatched caterpillars from a previous season. (Photo: Tawny Simisky, UMass Extension) Newly hatched spongy moth caterpillars have ballooned and settled on host plants to begin feeding on newly opened leaves in Millers Falls, MA as seen on 5/2/2023. Photo courtesy of: Nicole Keleher, MA Department of Conservation and Recreation, Forest Health Program. Spongy moth caterpillars feeding on black birch in Sheffield, MA on 5/24/2023. (Photo courtesy of: Tom Ingersoll.)Spongy Moth: Lymantria dispar egg hatch was reported on April 18, 2023, in Great Barrington, MA (Berkshire County) and on 5/2/2023 in Erving, MA and Millers Falls, MA (Franklin County). Since then, we’ve had a confusing period of rain events and saturation alternating with dry soils, and cool weather (including in some spots frosts and snow flurries, depending upon location) alternating with unseasonably warm spells. (See May 26, 2023, Landscape Message for more details.)

Spongy moth caterpillars have been observed molting and passing through different instars as they develop in Berkshire County, MA. Caterpillars are still relatively small, but many are likely larger than the size that can be treated by Bacillus thuringiensis Kurstaki (Btk; greater than ¾ inch in length). See photo courtesy of Tom Ingersoll from 6/5/2023. The Massachusetts Department of Conservation and Recreation reports that frost damage to oak trees in pockets of western MA (as well as central MA) make it difficult to discern where we currently stand with spongy moth feeding impact. Nicole Keleher, Forest Health Program Director, reports that there is concern for oak trees impacted by the frost defoliation, in the event that they refoliate (push out a new set of leaves) only just in time for the older instar spongy moth caterpillars to feed on them. Only time will tell.

The expectation is that parts of western MA may experience noticeable defoliation by this insect again in 2023. By the end of June and the beginning of July, most of this feeding will have occurred and we will be able to tell whether or not defoliation has again been significant. Additionally, by that time, whether or not the population is hit by an epizootic of the spongy moth caterpillar killing fungus (Entomophaga maimaiga) will be noticeably detectable as well.

For more information about spongy moth, view the first episode of InsectXaminer.

Why did the common name for Lymantria dispar change recently? More information is available here:

  • Spotted Lantern Fly egg masses (T. Simisky)Spotted Lanternfly: (Lycorma delicatula, SLF) is a non-native, invasive insect that feeds on over 103 species of plants, including many trees and shrubs that are important in our landscapes. It overwinters as an egg mass, which the adult female insect lays on just about any flat surface. Pictures of egg masses can be seen here:

Spotted lanternfly egg masses have begun hatching as of the week of May 26, 2023, in Springfield, MA! The MA Department of Agricultural Resources (MDAR) reports seeing spotted lanternfly nymphs hatching from and resting on their egg masses in areas of Springfield where a breeding population of this insect has become established. Some nymphs had already begun to migrate away from the locations where their egg masses are located. Shortly after egg hatch was observed in Springfield, it was also confirmed in Worcester, MA in areas where SLF has become established. Egg hatch has not yet been observed by the MA Department of Agricultural Resources in Shrewsbury or Fitchburg, MA. UMass Extension thanks MDAR for sharing these reports! Updates about spotted lanternfly egg hatch in Massachusetts may soon be posted by MDAR, here: .

Currently, the only established populations of spotted lanternfly in Massachusetts are in Fitchburg, Shrewsbury, Worcester, and Springfield MA. Therefore, there is no reason to be preemptively treating for this insect in other areas of Massachusetts. If you suspect you have found spotted lanternfly in additional locations, please report it immediately to MDAR here: If you are living and working in the Fitchburg, Shrewsbury, Worcester, and Springfield, MA areas, please be vigilant and continue to report anything suspicious.

For More Information:

From UMass Extension:

*New*: Spotted Lanternfly Management Guide for Professionals:

*Note that management may only be necessary in areas where this insect has become established in Massachusetts, and if high value host plants are at risk. Preemptive management of the spotted lanternfly is not recommended.

Fact Sheet:

Check out the InsectXaminer Episode about spotted lanternfly adults and egg masses!

From the MA Department of Agricultural Resources:

Fact Sheet and Map of Locations in MA:

Spotted Lanternfly Management Guide for Homeowners in Infested Areas:

*New*: Spotted Lanternfly Look-alikes in MA:

*New*: Spotted Lanternfly Egg Mass Look-alikes:

  • Asian Longhorned Beetle: (Anoplophora glabripennis, ALB) Look for signs of an ALB infestation which include perfectly round exit holes (about the size of a dime), shallow oval or round scars in the bark where a female has chewed an egg site, or sawdust-like frass (excrement) on the ground nearby host trees or caught in between branches. Be advised that other, native insects may create perfectly round exit holes or sawdust-like frass, which can be confused with signs of ALB activity.

The regulated area for Asian longhorned beetle is 110 square miles encompassing Worcester, Shrewsbury, Boylston, West Boylston, and parts of Holden and Auburn. If you believe you have seen damage caused by this insect, such as exit holes or egg sites, on susceptible host trees like maple, please call the Asian Longhorned Beetle Eradication Program office in Worcester, MA at 508-852-8090 or toll free at 1-866-702-9938.

To report an Asian longhorned beetle find online or compare it to common insect look-alikes, visit: or

  • White Spotted Pine Sawyer (WSPS): Monochamus scutellatus adults can emerge in late May throughout July, depending on local temperatures. White spotted pine sawyers have been seen in Western Massachusetts in recent weeks, arriving right on time in the last two weeks of May. This is a native insect in Massachusetts and is usually not a pest. Larvae develop in weakened or recently dead conifers, particularly eastern white pine (Pinus strobus). However, the white spotted pine sawyer looks very similar to the invasive Asian Longhorned Beetle, Anoplophora glabripennis, ALB. ALB adults do not emerge in Massachusetts until July and August. Beginning in July, look for the key difference between WSPS and ALB adults, which is a white spot in the top center of the wing covers (the scutellum) on the back of the beetle. White spotted pine sawyer will have this white spot, whereas Asian longhorned beetle will not. Both insects can have other white spots on the rest of their wing covers; however, the difference in the color of the scutellum is a key characteristic. See the Asian longhorned beetle entry above for more information about that non-native insect.
  • Adult Emerald Ash Borer (T. Simisky)Emerald Ash Borer: (Agrilus planipennis, EAB) has been detected in at least 11 out of the 14 counties in Massachusetts.A map of these locations across the state may be found here: . Additional information about this insect is provided by the MA Department of Conservation and Recreation, here:

This wood-boring beetle readily attacks ash (Fraxinus spp.) including white, green, and black ash and has also been found developing in white fringe tree (Chionanthus virginicus) and has been reported in cultivated olive (Olea europaea). Signs of an EAB infested tree may include D-shaped exit holes in the bark (from adult emergence), “blonding” or lighter coloration of the ash bark from woodpecker feeding (chipping away of the bark as they search for larvae beneath), and serpentine galleries visible through splits in the bark, from larval feeding beneath. It is interesting to note that woodpeckers are capable of eating 30-95% of the emerald ash borer larvae found in a single tree (Murphy et al. 2018). Unfortunately, despite high predation rates, EAB populations continue to grow. However, there is hope that biological control efforts will eventually catch up with the emerald ash borer population and preserve some of our native ash tree species for the future.

  • Jumping Worms: Amynthas spp. earthworms, collectively referred to as “jumping or crazy or snake” worms, overwinter as eggs in tiny, mustard-seed sized cocoons found in the soil or other substrate (ex. compost). Immature jumping worms hatch from their eggs by approximately mid-to-late May. It may be impossible to see them at first, and it may be more likely that jumping worms are noticed when the first adults begin to appear at the end of May and in June. It is easy to misidentify jumping worms (ex. mistake European earthworms for jumping worms) if only juveniles are found. In August and September, most jumping worms have matured into the adult life stage and identification of infestations is more likely to occur at that time of year.

For More Information, see these UMass Extension Fact Sheets:

Earthworms in Massachusetts – History, Concerns, and Benefits

Jumping/Crazy/Snake Worms – Amynthas spp.

A Summary of the Information Shared at UMass Extension’s Jumping Worm Conference in January 2022

Invasive Jumping Worm Frequently Asked Questions (Over 70 Questions and their Answers)

Tree & Shrub Insect Pests (Native and Invasive):

  • Andromeda Lace Bug: Stephanitis takeyai is most commonly encountered on Japanese Andromeda. Eggs are tiny and inserted into the midveins on the lower surface of the leaf and covered with a coating that hardens into a protective covering. 5 nymphal stages are reported. Nymphs are different in appearance from the adults, often covered with spiky protrusions. 3-4 generations per year have been observed in New England, with most activity seen between late-May into September (starting at approximately 120 GDD’s, Base 50°F). Both nymphs and adults can be seen feeding on leaf undersides. Adults have delicate, lace-like wings and what appears to be an "inflated hood" that covers their head. Adults are approximately 1/8 of an inch long. Arrived in the US in Connecticut in 1945 from Japan (Johnson and Lyon, 1991).

Can cause severe injury to Japanese andromeda, especially those in full sun. Mountain Andromeda (Pieris floribunda) is highly resistant to this pest. Like other lace bugs, this insect uses piercing-sucking mouthparts to drain plant fluids from the undersides of the leaves. Damage may be first noticed on the upper leaf surface, causing stippling and chlorosis (yellow or off-white coloration). Lace bug damage is distinguished from that of other insects upon inspecting the lower leaf surface for black, shiny spots, "shed" skins from the insects, and adult and nymphal lace bugs themselves.

A first sign of potential lace bug infestation is stippling or yellow/white colored spots or chlorosis on host plant leaf surfaces. Lace bugs excrete a shiny, black, tar-like excrement that can often be found on the undersides of infested host plant leaves. Flip leaves over to inspect for this when lace bug damage is suspected.

Mountain Andromeda (Pieris floribunda) is considered to be highly resistant to this insect and can be used as an alternative for such plantings, along with other lace bug-resistant cultivars. Consider replacing Japanese Andromeda with mountain andromeda as a way to manage for this pest. Natural enemies are usually predators, and sometimes not present in large enough numbers in landscapes to reduce lace bug populations. Structurally and (plant) species complex landscapes have been shown to reduce azalea lace bug (Stephanitis pyrioides) populations through the increase of natural enemies.

  • Arborvitae Leafminer: In New England and eastern Canada, four species of leafminers are known to infest arborvitae. These include Argyresthia thuiella, A. freyella, A. aureoargentella, and Coleotechnites thujaella. The arborvitae leafminer, A. thuiella, is the most abundant of these and has the greatest known range when compared to the others. (It is also found in the Mid-Atlantic States and as far west as Missouri). Moths of this species appear from mid-June to mid-July and lay their eggs. The damage caused by all of these species is nearly identical. Trees, however, have been reported to lose up to 80% of their foliage due to arborvitae leafminer and still survive. At least 27 species of parasites have been reported as natural enemies of arborvitae leafminers, the most significant of which may be a parasitic wasp (Pentacnemus bucculatricis). Arborvitae leafminer damage causes the tips of shoots and foliage to turn yellow and brown. If infestations are light, prune out infested tips.
  • Azalea Lace Bug: Stephanitis pyrioides is native to Japan. The azalea lace bug deposits tiny eggs on the midveins on leaf undersides. They then cover the area where the egg was inserted with a brownish material that hardens into a protective covering. Each female may lay up to 300 eggs (University of Florida). Nymphs hatch from the eggs and pass through 5 instars. The length of time this takes depends on temperature. Between 2 and 4 generations may be completed in a single year. In Maryland, there are four generations per year. Adults are approximately 1/10 of an inch in length with lacy, cream colored, transparent wings held flat against the back of the insect. Wings also have black/brown patches. Adults of this species also possess a "hood" over their head. Nymphs are colorless upon hatch from the egg, but develop a black color as they mature and are covered in spiny protrusions.

Immatures and adults use piercing-sucking mouthparts to remove plant fluids from leaf tissues. This feeding leaves behind white-yellow stippling on the upper surface of host plant leaves, even though the insects themselves feed on the underside of the leaf. Plants in full sun are often particularly damaged by these insects. In heavy infestations, plants in full sun may be killed by the feeding of the azalea lace bug.

Begin scouting for azalea lace bugs when 120 GDD’s (Base 50°F) are reached. This species is active throughout the summer, following. Look for dark, black tar-like spots of excrement deposited by immature and adult lace bugs on the underside of susceptible host plant leaves, especially on leaves with white-yellow stippling visible on the upper surface. If lace bugs are not already known to the location, check susceptible hosts located in full sun first. Monitor plants for lace bug feeding from late April through the summer.

Plant azaleas in partial shade. Resistance has been reported in Rhododendron atlanticum, R. arborescens, R. canescens, R. periclymenoides, and R. prunifolium.

Many of the natural enemies reported for this insect are predators. They are rarely abundant enough to reduce damaging populations of lace bugs, especially on plants in sunny locations. Structurally and (plant) species complex landscapes have been shown to reduce azalea lace bug (Stephanitis pyrioides) populations through the increase of natural enemies.

  • Azalea Sawflies: There are a few species of sawflies that impact azaleas. Johnson and Lyon's Insects that Feed on Trees and Shrubs mentions three of them. Amauronematus azaleae was first reported in New Hampshire in 1895 and is likely found in most of New England. Adults of this species are black with some white markings and wasp-like. Generally green larvae feed mostly on mollis hybrid azaleas. Remember, sawfly caterpillars have at least enough abdominal prolegs to spell “sawfly” (so 6 or more prolegs). Adults are present in May, and females lay their eggs and then larvae hatch and feed through the end of June. There is one generation per year. Nematus lipovskyi has been reared from swamp azalea (Rhododendron viscosum). Adults of that species have been collected in April (in states to the south) and May (in New England) and larval feeding is predominantly in late April and May in Virginia and June in New England. One generation of this species occurs per year, and most mollis hybrid azaleas can be impacted. A third species, Arge clavicornis, is found as an adult in July and lays its eggs in leaf edges in rows. Larvae are present in August and September. Remember, Bacillus thuringiensis Kurstaki does not manage sawflies.
  • Bagworm bag (T. Simisky)Bagworm: Thyridopteryx ephemeraeformis is a native species of moth whose larvae construct bag-like coverings over themselves with host plant leaves and twigs. This insect overwinters in the egg stage, within the bags of deceased females from last season. Eggs may hatch and young larvae are observed feeding around mid-June, or roughly between 600-900 GDD’s. Egg hatch is coming soon! In recent years, an increase in bagworm activity (particularly in urban forests) in Massachusetts has been noticed by professionals. In 2023, reports of heightened bagworm presence have been made from Plymouth County, MA thus far. More information can be found here:
  • Black Vine Weevil: Otiorhynchus sulcatus adults are 0.35-0.51 inches in length and are therefore slightly larger than some of the other destructive species of Otiorhynchus. Adults are also black in color, all are female, and they cannot fly. This insect is native to Europe and is now found in the northern half of the United States and Canada. Adults will drop from foliage to the ground when disturbed and are easily hidden due to their camouflaged coloration. Adults require a few weeks of feeding before each female will lay up to 500 eggs in the soil near the base of the plant around the end of June, early-July. These eggs will hatch and larvae will burrow into the soil to feed on the roots of the plant. Larvae are white approx. 1/2 an inch in length with brown heads, legless, and C-shaped. This weevil usually overwinters as a partially developed larvae, but occasionally adults will seek shelter, such as homes, in which to overwinter. Larvae do a lot of destructive feeding in late-May, early- June just prior to pupation. Pupae are milky-white with visible appendages. One generation per year occurs in the Northeast. Many additional weevil species are pests of ornamental plants. Tiny, hemispherical notches in leaf margins are a sign of adult feeding, usually on lower branches. However, other weevils will cause this type of damage on rhododendron; it can only be used diagnostically on yew, as no other insects currently cause that type of damage on that host. The major damage is caused by larvae feeding on the rootlets. This can be a very serious pest.

Activity of the black vine weevil can be monitored using the following growing degree day ranges: 148-400 GDD's (overwintering adults; Source: Cornell Cooperative Extension) 1100–1665 GDD's (adults; Source: Robert Childs, UMass Extension), Base 50°F, March 1st Start Date. Monitor adults with crumpled burlap around plant base, as the adults hide in dark places during the day and are active at night. Pitfall traps around the base of infested plants may also be used. Look for notched leaves on host plants, particularly yew, starting in June. Larvae may be found on the roots of wilting host plants with notched leaves. Scouting is highly necessary in areas where this insect is an issue.

Some physical barriers to the adults (on the stem/base of the plant) have been suggested, since adults cannot fly and must crawl up the plant. Success varies. Knocking adults off the plant and onto a white surface, such as a sheet, so they are visible and can be collected and killed may be very time consuming (and must be done at night, when the adults are active). Some adults may be missed. Cleaning up beds and leaf litter/dropped branches can help remove favorable overwintering sites for the adults. Some rhododendrons are resistant to foliar damage.

Birds may be good predators of this insect. Beneficial nematode drenches are available for the larvae, and are most effective in containerized plants. Apply when larvae are present and when temperatures are favorable to the species of nematode being used. Follow instructions carefully as the nematodes are living organisms and proper treatment can increase efficacy (such as watering before/after nematode application).

  • Boxwood Leafminer: Monarthropalpus flavus partly grown fly larvae overwinter in the leaves of susceptible boxwood. Yellowish mines may be noticeable on the undersides of leaves. This insect grows rapidly in the spring, transforming into an orange-colored pupa. After pupation, adults will emerge and white colored pupal cases may hang down from the underside of leaves where adults have emerged. Adults may be observed swarming hosts between 300-650 GDD’s, or roughly the end of May through June. Most cultivars of Buxus sempervirens and B. microphylla are thought to be susceptible. Resistant cultivars such as ‘Vardar Valley’ and ‘Handsworthiensis’ are good choices at sites where this insect has been a problem. For more information, visit:
  • Boxwood Mite: Eurytetranychus buxi overwinter as tiny eggs on boxwood leaves and hatch mid-spring. These mites are tiny (about the size of a period) and difficult to detect. Feeding may cause plants to appear off-color. If management is deemed necessary, the timing for treatment may be between 245-600 GDD’s.
  • Boxwood Psyllid: Psylla buxi feeding can cause cupping of susceptible boxwood leaves. Leaf symptoms/damage may remain on plants for up to two years. English boxwood may be less severely impacted by this pest. Eggs overwinter, buried in budscales, and hatch around budbreak of boxwood. Eggs may hatch around 80 GDD’s. While foliar applications may be made between 290-440 GDD’s, the damage caused by this insect is mostly aesthetic. Therefore, typically, management is not necessary. For more information, visit: .
  • Dogwood Borer: Synanthedon scitula is a species of clearwing moth whose larvae bore not only into dogwood (Cornus), but hosts also include flowering cherry, chestnut, apple, mountain ash, hickory, pecan, willow, birch, bayberry, oak, hazel, myrtle, and others. Kousa dogwood appear to be resistant to this species. Signs include the sloughing of loose bark, brown frass, particularly near bark cracks and wounds, dead branches, and adventitious growth. The timing of adult emergence can be expected when dogwood flower petals are dropping and weigela begins to bloom. Adult moth flights continue from then until September. Emergence in some hosts (ex. apple) appears to be delayed, but this differs depending upon the location in this insect’s range. Eggs are laid singly, or in small groups, on smooth and rough bark. Female moths preferentially lay eggs near wounded bark. After hatch, larvae wander until they find a suitable entrance point into the bark. This includes wounds, scars, or branch crotches. This insect may also be found in twig galls caused by other insects or fungi. Larvae feed on phloem and cambium. Fully grown larvae are white with a light brown head and approx. ½ inch long. Pheromone traps and lures are useful for determining the timing of adult moth emergence and subsequent management.
  • Dogwood Sawfly: Macremphytus tarsatus has one generation per year. The larvae of the dogwood sawfly overwinter in decaying wood and occasionally compromised structural timber. An overwintering "cell" is created in this soft wood. Pupation occurs in the springtime and adults can take a lengthy time to emerge, roughly between late May and July. 100+ eggs are laid in groups on the underside of leaves. Eggs hatch and the larvae feed gregariously, initially skeletonizing leaves. As the caterpillars grow in size, they are capable of eating the entire leaf with the exception of the midvein. Larval appearance varies greatly throughout instars, so much so that one might mistake them for multiple species. Early instars are translucent and yellow, but as the caterpillars grow they develop black spots (over yellow) and become covered in a white powder-like material. Larvae and their shed skins may resemble bird droppings. Full grown larvae begin to wander in search of a suitable overwintering location. Rotting wood lying on the ground is preferred for this.

Foliage of dogwood, especially gray dogwood (Cornus racemosa) may be impacted. Skeletonizes leaves at first, then eats all but the midvein.

  • Eastern Tent Caterpillar: Malacosoma americanum eggs overwinter on host plant twigs. Egg hatch typically occurs when wild cherry leaves begin to unfold and young caterpillars may emerge by late-April through the first two weeks in May (90-190 GDD’s). Susceptible hosts include cherry and crabapple. Other host plants whose leaves are fed upon by this native insect can include apple, ash, birch, willow, maple, oak, poplar, and witch-hazel. Where practical, prune out and remove new eastern tent caterpillar tents before they become larger as the caterpillars continue to feed. Eastern tent caterpillars are native to Massachusetts and have many associated natural enemies (parasites and predators) that help regulate populations. Unless these caterpillars are actively defoliating specimen trees in a landscaped setting, we can coexist with this particular herbivore native to our forests.
  • Elm Leaf Beetle: Xanthogaleruca (formerly Pyrrhalta) luteola is found on American elm (Ulmus americana; not preferred), Chinese Elm (Ulmus parvifolia; not preferred), English Elm (Ulmus procera; preferred host), Japanese Zelkova (Zelkova serrata), and Siberian Elm (Ulmus pumila; preferred host).

This species was accidentally introduced into the eastern United States early in the 1800's. Since then, it has been found throughout the USA anywhere elms are located. It also occurs in eastern Canada. The adult elm leaf beetle overwinters in protected areas, such as the loose bark of trees, but can also be a nuisance when it tries to invade homes in search of overwintering protection. Beetles will try to enter houses or sheds in the fall.

In the spring, the adult beetles will fly back to the host plant and chew small, semi-circular holes in the leaves. The adult female can lay 600-800 yellow eggs in her life. Eggs are laid in clusters on the leaves and resemble pointy footballs. Larvae are tiny, black, and grub-like when they hatch from the egg. Young larvae will skeletonize the undersides of leaves. As they grow in size, the larvae become yellow-green with rows of black projections. Oldest larvae may appear to have two black stripes along their sides, made from the black projections. There are 3 larval instars. Mature larvae will wander down the trunk of the host tree and pupate in the open on the ground at the tree base or in cracks and crevices in the trunk or larger limbs. They spend approximately 10 or so days as a pupa, and then the adults emerge. Those adults will fly to the foliage of the same host plant or other adjacent potential hosts in the area, where they will lay eggs. In the fall, the adults will leave the host plant in search of overwintering shelter. In most locations in the USA, two generations of this insect are possible per year. In warmer locations, 3-4 generations per year are possible.

Leaves are skeletonized by the larvae. Skeletonization may cause the leaf to turn brown or whitish. Adults are capable of chewing through the leaf, often in a shothole pattern. When in very large populations, they are capable of completely defoliating plants. Populations of this insect can fluctuate from year to year, and often management is not necessary if populations are low. However, defoliation for consecutive seasons may lead to branch dieback or death of the entire tree.

  • Elm Leafminer: Fenusa ulmi is a European species that was introduced into the United States prior to 1898. This insect is a leafmining sawfly whose adults are approximately 3 mm. in length and look like tiny black wasps. In New England, the adult is said to be active in May at which point it lays eggs in host plant leaf tissues through slits cut in the leaf using a saw-like ovipositor (egg laying structure of the females). It takes the eggs approximately 1 week to hatch, and tiny larvae begin to mine blotches in host plant leaves. Mines may appear as tiny, whitish spots confined between leaf lateral veins. Tissues between the two layers of epidermis are eaten. When several mines coalesce, large blotches are formed. By late spring, the larvae have completed their development and will cut their way out of the leaf, drop to the ground, and prepare to pupate in a papery cocoon buried in the soil beneath the host plant. They are thought to remain as pre-pupa through the summer, fall, and winter only to pupate and emerge as adults the following spring. One generation is thought to occur per year.

Damaged leaves may remain on host plants throughout the season. Blotch-like mines occur between lateral leaf veins and may run together to form a large mine. Injured leaves may turn brown and the mined areas might drop out of the leaf over time, leaving behind holes. Aesthetic damage may occur, and in heavy infestations healthy leaf loss may be an issue. Look for mines beginning at the end of May and in June. Growing degree days for elm leafminer monitoring are: 263–530 GDD's, Base 50F, March 1st Start Date. (Source: Cornell Cooperative Extension.) Large infestations may result in defoliation. Leaves found with sawfly caterpillars within can be removed by hand and destroyed, particularly on small trees with light infestations. No significant natural enemies are currently reported.

  • Elongate Hemlock Scale: Fiorinia externa is found on eastern, Carolina, and Japanese hemlock, as well as yew, spruce, and fir. The elongate hemlock scale may overwinter in various life stages, and overlap of many developmental stages at any given time can be observed throughout much of the season. Treatments for the crawler, or mobile, stage of this insect may be made in late May through mid-June, or between 360-700 GDD’s, base 50°F. Nitrogen fertilizer applications may make elongate hemlock scale infestations worse. For more information, visit:
  • Euonymus Caterpillar: Yponomeuta cagnagella is of European origin and widespread in distribution throughout Europe. It was first reported in North America in Ontario in 1967. The euonymus caterpillars (larvae) feed in groups and envelop the foliage of the host plant in webs as they feed. Hosts include: Euonymus europaeus (tree form), E. kiautschovicus, E. alatus, and E. japonicus. Mature caterpillars are just under an inch in length, creamy yellow-gray in color with black spots and a black head capsule. By late June, these larvae pupate in white, oval-shaped cocoons which are typically oriented together vertically either on host plants or non-hosts in the area. Cocoons can be found in cracks and crevices, or webbed together leaves. The adult moth emerges in late June in most locations. The adult female secretes a gummy substance over her eggs which will harden, making them even more difficult to see. Eggs hatch by mid-August, at which time the tiny larvae prepare to overwinter beneath their eggshell-like covering. These larvae are inactive until the following year, when caterpillars group together to feed on newly emerging leaves, creating a mess of webs as they feed. There is one generation per year. Plants may be partially or entirely defoliated. Management of young, actively feeding caterpillars with Bacillus thuringiensis is possible if deemed necessary, however many species of Euonymus are considered invasive themselves. Check out Episode 3 of InsectXaminer to see the euonymus caterpillar in action and learn more about its life cycle.
  • Euonymus Scale: Unaspis euonymi is an armored scale that can be found on euonymus, holly, bittersweet, and pachysandra. This insect can cause yellow spotting on leaves, dieback, and distorted bark. For crawlers, early June timing is suggested between 533-820 GDD’s for management. (Eggs begin to hatch in early June.)
  • European Elm Scale: Gossyparia spuria is a type of felt scale. First noted in New York in 1884, this non-native scale is now widespread in North America and is found on native and European elms, but also rarely on hackberry and Zelkova. This insect can cause yellowing of foliage, premature leaf drop, and eventually dieback on its host. Honeydew and thus sooty mold are produced. By the end of June, females will lay eggs that hatch into bright yellow crawlers, which will disperse to the midrib and leaf veins on the underside of elm leaves where they will remain to feed. Crawlers are tiny and magnification is necessary to observe. Natural enemies such as parasitic wasps and predatory insects have been reported as successful in managing this insect.
  • Fletcher Scale: Parthenolecanium fletcheri is a soft scale pest of yew, juniper, and arborvitae. Feeding scales, especially on yew, result in honeydew and sooty mold, needle yellowing, and at times, premature needle drop. There is one generation per year. Nymphs develop and adult females lay eggs (on average 500-600) in May that hatch by June. Dead females conceal egg masses beneath. Crawlers migrate short distances to branches and may be concentrated on certain branches of a particular plant.
  • Large forest tent caterpillars.  (Photo: Tawny Simisky, UMass Extension) Forest Tent Caterpillar: Malacosoma disstria egg hatch occurs between 192-363 GDD’s, base 50°F, by mid-late May and caterpillars may be active for at least 5-6 weeks following. Susceptible hosts whose leaves are fed on by this insect include oak, birch, ash, maple, elm, poplar, and basswood. This native insect has many natural enemies, including some very effective pathogens that typically regulate populations. However, outbreaks of this insect can occur on occasion.
  • Fruitworms: Lithophane and Orthosia species are part of a complex of at least 10 species that are sometimes collectively referred to as "fruitworms" or "green fruitworms". These are native insects that feed on similar hosts at the same time and cause similar feeding damage. One generation is reported per year. Often, Lithophane antennata is the species that is referred to as the "green fruitworm". The adult moth stage overwinters in sheltered areas after becoming active in September and November. The following spring, they become active again when temperatures are above 60F. Adult moths mate and females lay eggs singly or in masses. Adults are light brown in color and approximately 1 inch in length. Eggs hatch and young larvae crawl to the opening buds of their host plants and begin to feed, usually beginning around April or May in Massachusetts. Caterpillars mature as the leaves of their host plants mature. Fruitworm caterpillars are often pale green with faint white stripes along the length of their bodies and can be up to 1.25 to 1.5 inches in length at maturity. Larvae have six instars (molting in between each) and once mature, they move to the soil to pupate. Fruitworm caterpillars may be observed feeding on their hosts until approximately the end of June. Other commonly reported species of fruitworm in the eastern US include Orthosia hibisci and Amphipyra pyramidoides.

Because fruitworms begin feeding so early in the season, they are capable of destroying the buds of their host plants. Their feeding eventually produces tattered foliage. However, these native insects do not always cause noticeable damage to their host plants, and often are found in low populations that are not damaging. In ornamental settings, the feeding activity of these insects may not be significant enough to warrant management, unless it is a particularly high population year. The largest issue regarding fruitworms is for the apple and stonefruit industries. For example, in apple, certain species of fruitworm feeding damage may cause many apples to abort or if they do mature to harvest, they may have deep corky scars and indentations (but this depends upon the species of insect).

Scout susceptible host plants beginning in April and May in Massachusetts for defoliation caused by caterpillars. Fruitworms are considered sporadic pests, and low populations can be tolerated, so management is often not necessary unless population outbreaks are reported. If few caterpillars are found, remove them from ornamental plants by hand where practical. Certain parasitic wasps (Apanteles, Eulophus, Meteorus, and Ophion spp.) are reported in fruitworm populations and may help prevent noticeable damage in managed landscapes (UC IPM Pest Management Guidelines, 2017). However, natural enemies are not reported to be significant enough in their impact on fruitworm populations in orchards.

  • Hemlock Looper: Two species of geometrid moths in the genus Lambdina are native insects capable of defoliating eastern hemlock, balsam fir, and white spruce. Adult moths lay their eggs on the trunk and limbs of hosts in September and October, and eggs will hatch by late May or early June. (L. fiscellaria caterpillars may be active between 448-707 GDD’s.) Monitor susceptible hosts for small, inch-worm like caterpillars. Where populations are low, no management is necessary. Hemlock loopers have several effective natural enemies.
  • Honeylocust Plant Bug: Diaphnocoris chlorionis feeding results in tiny yellowish-brownish spots on leaves, leaf distortion, and in some cases, defoliation. (There are at least 7 species of plant bugs that feed on honeylocust, Gleditsia triacanthos.) There is one generation per year. Immatures and adults feed on foliage and light to moderately damaged foliage may persist throughout the growing season. Honeylocust plant bugs overwinter as eggs laid just beneath the bark surface of 2 and 3 year old twigs. Eggs hatch just after vegetative bugs of the host begin to open. Young nymphs crawl to the opening leaflets and begin feeding and the most significant damage occurs at that time, when the insect is hidden from view. Nymphs develop into adults around May-July. This insect can be targeted between 58-246 GDD’s, base 50°F.
  • Hydrangea Leaftier: Olethreutes ferriferana is a moth in the Family Tortricidae whose caterpillars use silk applied to the edges of two newly expanding hydrangea leaves to tie them together to create an envelope-like structure within which they feed. These leaf-envelopes tend to occur near the tips of plant stems and can be very obvious. As a result, the two tied leaves may not fully expand when compared to healthy, non-impacted leaves. Many envelope or purse-like structures can be seen throughout the plants and may be found from the base to the top of the plant. By gently pulling apart the tied-together leaves, tiny caterpillars are revealed within and able to be mechanically managed by crushing the individual caterpillars.

Caterpillars are green and partially transparent with a black head capsule and a black thoracic shield which is found on the top of the body segment located directly behind the head. Pupation is thought to occur in the ground nearby host plants, so the insect drops to the ground to pupate where it overwinters. Pupation occurs sometime in June. Adults are found in the spring and are small white and brown moths. Eggs are laid on branch tips of various species of hydrangea. Only one generation is known per year. This insect, although creating visible and interesting damage to hydrangea, is not usually considered to be a serious pest – although occasional localized problematic populations have been reported. Removing leaf-envelopes in the early spring or pinching them to kill the caterpillar within can help reduce populations on individual plants.

  • Imported willow leaf beetle adults. (Photo: Tawny Simisky, UMass Extension) Imported Willow Leaf Beetle: Plagiodera versicolora adult beetles overwinter near susceptible hosts. Adult beetles will chew holes and notches in the leaves of willow once they become available. Females lay yellow eggs in clusters on the undersides of leaves. Larvae are slug-like and bluish-green in color. They will feed in clusters and skeletonize the leaves. Most plants can tolerate the feeding from this insect, and foliage will appear brown. Repeated yearly feeding can be an issue, in which case management of the young larvae may be necessary. Take care with treatment in areas near water.

Check out Episode 4 of InsectXaminer to see the imported willow leaf beetle in action.

  • Lecanium Scales (Oak): Parthenolecanium quercifex overwinters as a second instar nymph on oak twigs. Females will begin feeding and mature in the spring, from mid-April to early May and eggs may be laid between late May and into June. Eggs hatch in June or early July and crawlers migrate to host plant leaves where they spend the summer and migrate as second instars back to host plant twigs in the fall.
  • Lilac Borer: Podosesia syringae is a clearwing moth pest of lilac, privet, fringetree, and ash. (It is also known as the ash borer, not to be confused with the emerald ash borer.) Adults mimic paper wasps. Larvae are wood-boring, and signs and symptoms include branch dieback, holes, and occasionally, sawdust-like frass accumulated on bark. Larvae bore into stems, trunks, and branches, chewing an irregularly shaped entrance hole. Peak adult moth flights may occur in the northern portion of this insect’s range in June and is usually over by August 1st. Pheromone traps can be used to time adult emergence. Adult females lay flattened, oval, and tan eggs that are deposited singly or in clusters on bark crevices, ridges, and sometimes smooth bark; but usually laid in or near wounds in the bark. On average, 395 eggs are laid by each female. After hatch, larvae chew into the bark and feed laterally and then vertically in phloem tissue. Larvae overwinter in tunnels in the final instar and resume feeding in the spring. Adults emerge through a round exit hole (4-5 mm. in diameter). This insectmay be targeted between 200-299 GDD’s, base 50°F.
  • Lily leaf beetle adults. (Photo: Tawny Simisky, UMass Extension) Lily Leaf Beetle: Lilioceris lilii adults overwinter in sheltered places. As soon as susceptible hosts such as Lilium spp. (Turk’s cap, tiger, Easter, Asiatic, and Oriental lilies) and Fritillaria spp. break through the ground, the adult lily leaf beetles are known to feed on the new foliage. (Note: daylilies are not hosts.) Adult lily leaf beetles were observed to be active in Hanson, MA on 4/14/2023. Typically, in May, mating will occur and each female will begin to lay 250-450 eggs in neat rows on the underside of the foliage. If there are only a few plants in the garden, hand picking and destroying overwintering adults can help reduce local garden-level populations at that time.

Check out Episode 3 of InsectXaminer to see the lily leaf beetle in action.

  • Magnolia Scale: Neolecanium cornuparvum overwinters as first instar nymphs which are elliptical, and dark slate gray in color and can usually be found on the undersides of 1 and 2 year old twigs. Nymphs may molt by late April or May and again by early June at which time the scales may be purple in color. Eventually nymphs secrete a white powdery layer of wax over their bodies. Avoid applications to opening buds or blooms. For more information, visit: .
  • Pitch mass created by the activity of the pitch mass borer seen on Norway spruce. Photo courtesy of: Jim Rassman, Service Forester, MA Department of Conservation and Recreation.Pitch Mass Borer: Synanthedon pini is a native clearwing moth whose larvae feed within various pines and spruce. Feeding by the larvae (caterpillars) of this insect causes pitch masses to form on host plants. Two or three years are required for this insect to complete its life cycle, with adult moths present during the summer. Adult pitch mass borer moths may resemble wasps. Adult males and females are blue/black from above, marked with a patch of red/orange on the underside of the abdomen, with some orange on the top of the fourth abdominal segment. Orange is also found along the sides of the abdomen. Forewings are black/blue in color and opaque with wing length of 0.47 to 0.59 inches. Adults are said to emerge, mate, and females lay eggs on their hosts some time in July. By the late summer, the larvae (immatures; caterpillars) bore into their host plant, tunneling through the trunks, often directly beneath a branch. Larvae have uniformly dark brown heads, white bodies, and prolegs with rows of 6-8 crochets on the bottom of their "feet". At the site of the borer wound, large amounts of pitch exude from the tree in a hemispherical mass above the larval tunnels. Larvae continue to feed and develop in the tree through the following year, and it is thought that caterpillars may take up to two years to mature. Masses may be 3-4 inches in diameter. Pupation occurs in a subsequent end of May through June in time for adult emergence by July and August. Pupal cells are formed within the pitch mass and lined with silk (Beuttenmüller, 1901). Pupae are 0.73 inches long and light brown in color (Kellicott, 1881).

Adult moths are active during the summer. Following egg laying and egg hatch, the larvae tunnel under the bark to the cambium. Obvious, large globs of pitch appear on trunks. Occurs sporadically on individual trees. Host trees with active caterpillars have pitch masses that may appear coated in a white, powdery substance. Larvae may also preferentially bore into the host beneath a broken branch or scar. This insect will attack large trees, up to 30-40 feet from the ground. Healthy trees are also preferentially utilized. Overall damage to the health of the host tree is typically not extensive, and therefore chemical management of this insect is often unnecessary.

Pitch can be removed and the single larva within destroyed. Physical/mechanical management of this insect, if it can be safely done, is a great way to manage the pitch mass borer on individual specimen trees. The act of just pulling the caterpillar from its pitch mass will kill it - much to the frustration of history's entomologists looking to study them - as soon as contact of the pitch is made with the caterpillar's body and hardens and adheres to them. Parasitism by natural enemies is reported to be relatively common. Parasitic wasps in the family Eulophidae are noted but not specified, as well as a caterpillar-eating species of fly (Engelhardt, 1946).

  • Rhododendron Borer: Synanthedon rhododendri is one of the smallest of the native clearwing moths. Rhododendrons are preferred hosts, although mountain laurel, and deciduous azaleas can be heavily infested, especially if they are planted in close proximity to rhododendrons. Injury may be first noticed in the fall (leaves lose their sheen, then become pale green, then olive, then chlorotic) and can look similar to drought stress. On branches that seem to be stunted, look at limb crotches, scars, and other irregularities for sawdust stuck on bark or on the ground beneath these areas. In late May and early June, holes may contain pupal shed skins extending halfway out. Moth emergence occurs in the late-spring, early-summer. After mating, female moths seek out suitable egg laying locations (preferring wounded areas or limb crotches). The female lays her eggs and dies. Eggs hatch and larvae tunnel into the inner bark where they feed in tunnels that become packed with reddish frass pellets. By late fall, larvae move to the sapwood where they overwinter and resume feeding by mid-March. Pupation occurs in the spring and there is one generation per year. Prune out and destroy infested branches before late May/June. Monitor for adults in mid-May (192-298 GDD’s, base 50°F).
  • Roseslugs: Two species of sawfly can be found on the leaves of roses at this time. These small, caterpillar-like larvae will skeletonize the upper leaf surface and leave a “window-pane” like pattern behind. When present in large numbers, these insects are capable of defoliating their entire host. Caterpillars may feed until roughly mid-June, at which time they will pupate. Management options include an insecticidal soap spray or a product containing spinosad.
  • Spruce Bud Scale: Physokermes piceae is a pest of Alberta and Norway spruce, among others. Immatures overwinter on the undersides of spruce needles, dormant until late March. By April, females may move to twigs to complete the rest of their development. Mature scales are reddish brown, globular, 3 mm. in diameter, and found in clusters of 3-8 at the base of new twig growth. They closely resemble buds and are often overlooked. Crawlers are present around June.
  • Spruce Spider Mite: Oligonychus ununguis is a cool-season mite that becomes active in the spring from tiny eggs that have overwintered on host plants. Hosts include spruce, arborvitae, juniper, hemlock, pine, Douglas-fir, and occasionally other conifers. This particular species becomes active in the spring and can feed, develop, and reproduce through roughly June. When hot, dry summer conditions begin, this spider mite will enter a summer-time dormant period (aestivation) until cooler temperatures return in the fall. This particular mite may prefer older needles to newer ones for food. Magnification is required to view spruce spider mite eggs. Tapping host plant branches over white paper may be a useful tool when scouting for spider mite presence. (View with a hand lens.) Spider mite damage may appear on host plant needles as yellow stippling and occasionally fine silk webbing is visible.
  • Taxus Mealybug: Dysmicoccus wistariae will produce honeydew and lead to sooty mold growth, yellowing of needles, and sparsely foliated plants. Eventual dieback may be possible. This species is commonly associated with taxus in New England, but can be occasionally found on dogwood, rhododendron, Prunus spp., maple, andromeda, and crabapple. These mealybugs are found on stems and branches and particularly like to congregate at branch crotches. Taxus mealybug feeds in the inner bark tissue of the trunk and branches. Adult females are present from June to August and give birth to living young in the summer. Immatures overwinter. A single generation may occur per year in New England, but areas to the south can have multiple generations of this insect. Management may be targeted between 246-618 GDD’s, base 50°F. Horticultural oil and neem oil may be used.
  • Larval feeding by the viburnum leaf beetle (Pyrrhalta viburni) is apparent in areas where this insect has become established in Massachusetts at this time. Damage to host plant leaves photographed in Berkshire County, MA on 6/5/2023. (Photo courtesy of: Tom Ingersoll.) Viburnum Leaf Beetle: Pyrrhalta viburni is a beetle in the family Chrysomelidae that is native to Europe, but was found in Massachusetts in 2004. By 2008, viburnum leaf beetle was considered to be present throughout all of Massachusetts. Larvae are present and feeding on plants from approximately late April to early May until they pupate sometime in June. Much damage from viburnum leaf beetle feeding is currently apparent in areas of Massachusetts where this insect has become established. See photo courtesy of Tom Ingersoll from 6/5/2023. Adult beetles emerge from pupation by approximately mid-July and will also feed on host plant leaves, mate, and lay eggs at the ends of host plant twigs where they will overwinter. This beetle feeds exclusively on many different species of viburnum, which includes, but is not limited to, susceptible plants such as V. dentatum, V. nudum, V. opulus, V. propinquum, and V. rafinesquianum. Some viburnum have been observed to have varying levels of resistance to this insect, including but not limited to V. bodnantense, V. carlesii, V. davidii, V. plicatum, V. rhytidophyllum, V. setigerum, and V. sieboldii. More information about viburnum leaf beetle may be found at and here:
  • The woolly beech leaf aphid (Phyllaphis fagi) photographed in Berkshire County, MA on 6/5/2023. Note the spongy moth caterpillar (lower right of the leaf) with a shed/cast skin above and to the left of the molted caterpillar. Spongy moth feeding damage can also be seen on the leaf. (Photo courtesy of: Tom Ingersoll.) Woolly Beech Leaf Aphid: Phyllaphis fagi is a highly noticeable but typically not a damaging insect pest of European beech (Fagus sylvatica) and its cultivars. This piercing-sucking insect pest will not feed on American beech. It is often referred to as the woolly beech leaf aphid as the undersides of the host plant leaves are where they are most likely to be found. However, they may feed on host plant leaf petioles, fruit, and fruit stems. This species of aphid is gregarious, and often large groups of them are found on host plant leaf undersides along with large numbers of cast skins (shed exoskeletons following the molting of the insect). The woolly beech leaf aphid is "woolly" because of waxy, white filaments that cover the body - giving the aphids or any surface they coat a white appearance. The woolly beech leaf aphid is widely distributed in North America and found throughout the Northeast (essentially wherever European beech and its cultivars are grown.) These insects overwinter in the egg life stage tucked in bark crevices and near buds. Eggs hatch when spring temperatures warm, often near budbreak. Wingless viviparae (parthenogenetic females that give birth to live young) are pale green and covered with white, waxy wool. Wingless individuals are usually 2.0-3.2 mm long. Winged viviparae (parthenogenetic females that give birth to live young) are dark in color and densely coated in white, waxy wool. Multiple generations per year are possible, and in Europe at least 10 generations per year have been reported, with peak activity by mid-June (Iversen & Harding, 2007). As the insects feed on the host plant leaf undersides, they excrete large amounts of a liquid sugary waste product, known as honeydew. Honeydew can be attractive to stinging insects such as ants, bees, and wasps but also a growing place for fungi such as sooty mold. Sooty mold is often black in color and feeds not on the tree itself, but on the honeydew. The woolly beech leaf aphid is native to Europe, and has been introduced to North America, New Zealand, Australia, China, and Korea. Do not confuse this species of aphid with Grylloprociphilus imbricator (the beech blight aphid). The beech blight aphid is only found on the stems of American beech and is sometimes called the "boogie woogie aphid", owing to the fact that when disturbed, G. imbricator will "dance" and wave their rear ends back and forth in a most entertaining unison.

The woolly beech leaf aphid primarily feeds on the undersides of host plants leaves. Feeding with piercing-sucking mouthparts removes host plant fluids, causing either side of the leaf to turn downward on either side of the midvein, almost creating a pseudo-gall around the insects. This aphid species creates much honeydew and sooty mold. Huge populations in consecutive years cause little damage to their host plants found in the Northeastern United States, and as such chemical management options for this insect are seldom warranted. In Europe, the host plants are reportedly more severely impacted by woolly beech leaf aphid feeding. Monitor for the overwintering eggs on twigs near host plant buds, in particular in bark crevices within forked shoots (Kot and Kmiec, 2012). Aphids or cast skins can be monitored for on host plant leaf undersides. Peak activity of this insect may be seen by approximately mid-June.

Syringing aphids (spraying the infested leaves with a strong stream of water from a hose) has often been suggested as a cultural/mechanical management option for these soft-bodied insect pests. This may help reduce their population without the use of insecticides, which could have negative impacts on the natural enemies that often suppress woolly beech leaf aphid populations naturally. Proper planting, site selection, and tree maintenance also help reduce additional host plant stress which can be beneficial when managing insect pests of trees and shrubs. In Europe, a species of syrphid fly (Melangyna cincta) is a specialist predator of woolly beech leaf aphids, along with a mirid bug predator (Psallus varians) (Gilbert, 2005). The braconid wasp parasitoids Praon flavinode and Trioxys phyllaphidis are known to parasitize woolly beech leaf aphids in Europe, but are not currently reported from North America. In North America, natural enemies such as native or naturalized lady beetles and others are likely also feeding on woolly beech leaf aphid populations.

  • Yellow Poplar Weevil: Odontopus calceatus is also known as the sassafras weevil, the magnolia leafminer, or the tulip tree leafminer. This insect, as all of these common names suggest, feeds on yellow poplar (tulip tree; Liriodendron tulipifera), sassafras (Sassafras albidum), magnolia (Magnolia spp.), as well as bay laurel (Laurus nobilis). This insect is native to much of the eastern United States. Both the larvae and the adults of the yellow poplar weevil will feed on its hosts. Adults feed on the leaves and buds while the larvae mine the leaves. Adult feeding causes irregular holes to form in the leaves. Yellow poplar weevils overwinter as adults in sheltered areas, such as the leaf litter, around their hosts. In the early spring, they initiate feeding on the buds and newly opening leaves of the host plant. By May, they lay eggs in the midrib of the leaves on leaf undersides. Eggs will hatch and the larvae mine the leaves, creating blotch-like mines. This mining begins at the tip (point) of the leaf on tulip tree and Magnolia grandiflora hosts. Yellow poplar weevil larvae are white, legless, and approximately 2 mm long. Up to 9 larvae have been recorded in a single blotch mine. Larvae are mostly observed in late May and June. Pupation occurs in the leaf mines and adults of the new generation emerge to feed on leaves. Adults have been observed feeding as late as August in the southern portions of its range in the US (ex. Mississippi). Adult weevils may seek indoor shelters (such as homes) for overwintering protection. Feeding damage from this insect is not often reported as of economic importance, however in the southern parts of its range outbreaks have occasionally occurred (Johnson and Lyon, 1991). Natural enemies of the yellow poplar weevil have been reported, particularly hymenopteran parasitoids. Five species (Heterolaccus hunteri, Habrocytus piercei, Horismenus fraternus, Zagrammosoma multilineatum, and Scambus hispae) have been reported to kill 50% of yellow poplar weevil pupae (Burns and Gibson, 1968).

Concerned that you may have found an invasive insect or suspicious damage caused by one? Need to report a pest sighting? If so, please visit the Massachusetts Introduced Pests Outreach Project.

Reported by Tawny Simisky, Extension Entomologist, UMass Extension Landscape, Nursery, & Urban Forestry Program

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