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Landscape Message: June 16, 2023

Landscape Message: June 16, 2023
June 16, 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 14, 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









6/14/2023 12:00







6/14/2023 2:45














6/14/2023 4:00







6/14/2023 5:15







6/14/2023 4:00







6/14/2023 12:00







6/14/2023 5:30








n/a = information not available


US Drought Monitor:  The Cape and the islands, as well as parts of Southeastern MA, most of Worcester county, and all of Berkshire county (approximately 41% of the total area of Massachusetts) are classified as "D0: Abnormally Dry" as of Thursday 6/15:


Indicator Plants - Stages of Flowering (BEGIN, BEGIN/FULL, FULL, FULL/END, END)
Hydrangea macrophylla (bigleaf hydrangea) * Begin * * * * * *
Hydrangea arborescens (smooth hydrangea) * Begin/Full * * * * * *
Itea virginica (Virginia sweetspire) * Begin Begin Begin * Begin Full Begin
Tilia cordata (littleleaf linden) Begin End Begin Begin Begin Begin Full *
Rhus typhina (staghorn sumac) * * Begin Begin Begin Begin Begin/Full Frost killed buds
Ligustrum spp. (privet) Begin/Full Full Begin Begin Begin Begin Begin/Full *
Catalpa speciosa (Northern catalpa) Begin Full/End * Begin/Full Begin Begin/Full Begin/Full Begin
Sambucus canadensis (American elderberry) Begin Begin/Full Begin/Full Begin/Full Begin/Full Begin/Full Full *
Kalmia latifolia (mountain laurel) Full Full Full Full/End Full/End Full/End Full/End Full
Cotinus coggygria (common smokebush) Full Full Full Full/End Full/End Full/End Full/End Frost killed buds
Weigela florida (old fashioned weigela) Full/End End Full Full/End Full/End Full/End End Full/End
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions:

The average temperature for the period of June 7 thru June 14 was 61ºF with a high of 77ºF on June 14 and a low of 47ºF on June 10. The period began with several days of highs in the 60s and lows in the upper 40s followed by several days of highs in the 70s and lows around 60ºF. The period was dominated by cloudy and partly cloudy days. Precipitation did occur on several days during the period, however precipitation totals were low with just over a quarter inch for the entire period. Soil moisture is short.

Herbaceous plants in flower include false indigo (Baptisia australis), catmint (Nepeta spp.), foxglove (Digitalis pupurea), and shasta daisy (Leucanthemum vulgare). Woody plants in bloom include Kousa dogwood, climbing hydrangea (Hydrangea anomala subsp. petiolaris), American holly (Ilex opaca), tree lilac (Syringa reticulata), and viburnum (V. dentatum, V. nudum).


Some small areas of light defoliation (not widespread) from spongy moth can be found in the mid and lower Cape. Spongy moth caterpillars are still feeding in those areas. Other insects observed during the period include sawfly larvae on oak, rose slug sawfly on rose, dogwood sawfly on alternate leaf dogwood, white flies on Japanese holly, boxwood psyllid on boxwood, cottony camellia scale on euonymus and Japanese holly, turpentine beetle activity on pitch pine, and plant bug damage on viburnum. Aphids have been observed on many herbaceous and woody plants.

Disease symptoms or signs observed this period include beech leaf disease on American and European beech, apple scab on crabapple, sycamore anthracnose on sycamore, Venturia leaf and shoot blight on poplar, exobasidium gall on deciduous azalea and huckleberry, pear trellis rust on callery pear, guignardia leaf blotch on horsechestnut, and leaf spot on river birch. Some white pines are looking fairly thin and with a fair amount of recent needle loss. Some pitch pine are also looking rough with grayish/brown interiors from lophodermium needle cast. Red thread of turf has been active during this period.

Weeds in bloom include multiflora rose (Rosa multiflora), black swallowwort (Cynanchum louiseae), 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), and narrowleaf plantain (Plantago lanceolata).

Keep yourself protected from ticks.

Southeast Region (Dighton)

General Conditions:

Daytime high temperatures for the past week on both Sunday, June 11th, and Monday 12th were comfortably warm at 74°F. The lowest temperature over the week was 42°F on the morning of Friday, June 9th. It seems like we've left sweater weather behind us for now, but don't forget to have them handy for a while yet. Light showers on Wednesday, June 7th, and again on the following Saturday thru Sunday only totaled a meager half inch. The wind was highest on the 7th and 12th, at 15 mph. 

Plants in flower: Catalpa speciosa (Northern catalpa), Cotinus coggygria (smokebush), Hydrangea arborescens (smooth hydrangea), H. macrophylla (bigleaf hydrangea), Itea virginica (Virginia sweetspire), Kalmia latifolia (mountain laurel), Ligustrum spp. (privet), Sambucus canadensis (American elderberry), Weigela florida (old fashioned weigela)


Biting midges, no-see-ums, deer flies and mosquitoes are becoming an annoyance factor for workers. Windblown pine pollen is heavy, causing eye irritation, coughing, and sneezing. Cottonwood 'lint' is thick in the air in some neighborhoods. The NOAA/NCEI drought risk map released June 8th still shows all of Plymouth County and a growing portion of the southeastern corner of Bristol County as abnormally dry. Automated watering bans persist in many area towns. First-generation birch leaf miner damage on gray birch. Ash rust producing fallen leaves from the few lingering survivors of emerald ash borer (EAB). 

North Shore (Beverly)

General Conditions:

The weather this reporting period was relatively cool for this time of year with mostly cloudy or overcast skies. Day temperatures were in the mid 60s to low 70s and night temperatures in the high-40s to the mid 60s except on Monday, June 12 when the daytime temperature climbed to 77˚F and the nighttime temperature to 59˚F. At Long Hill, approximately 0.86 inches of rainfall was recorded. There is lush growth and lawns and gardens are looking good as a result of periodic rain showers during this period. Trees and shrubs are putting on new growth. 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, fomerly Kolkwitzia amabilis), mountain laurel (Kalmia latifolia), weigela (Weigela florida), mapleleaf viburnum (Viburnum acerifolium), Chinese stewartia (Stewartia sinensis), sawtooth stewartia (Stewartia serrata), Korean dogwood (Cornus coreana), American holly (Ilex opaca), and tree lilac (Syringa reticulata). Non-woody plants seen in bloom include: foam flower (Tiarella cordifolia), peony (Paeonia spp.), cranesbill (Geranium spp.), bleeding heart (Lamprocapnos spectabilis), Rodger's flower (Rodgersia aesculifolia), goat’s beard (Aruncus dioicus), Japanese primrose (Primula japonica), water lily (Nymphaea odorata), columbine (Aquilegia spp.), sweet woodruff (Galium odoratum), and annuals.


Leaf spots on rhododendron (G. Njue) Brown necrotic leaf spot was observed on some rhododendrons. These leaf spots may be caused by various fungi and they may be seen on rhododendrons and azaleas. Rake and destroy fallen leaves and avoid overhead watering that may spread the disease by splashing. Apple scab, caused by the fungus (Venturia inaequalis) and common on susceptible apples and crabapples, was observed on crabapples. It produces lesions that are most often seen on the leaves, causing those leaves to yellow and drop prematurely. Removing fallen leaves can help minimize the disease. Multiflora roses (Rosa multiflora), wine raspberry (Rubus phoenicolasius), garlic mustard (Alliaria petiolata) and several other weeds are in full bloom. Mosquitoes and ticks are still very active. Protect yourself with insect repellent when working outdoors, especially at dawn and at dusk.

East (Boston)

General Conditions

Late last week we had several days with cooler than usual temperatures in the 60’s and overcast skies. Higher temperatures returned, reaching 81ºF on June 11. Overnight lows averaged 53ºF. We received precipitation on five of the past seven days, accumulating 0.56 inches. We have received a total of 1.50 inches in June. Landscape plants have appreciated the additional moisture. Pollinators are out in abundance visiting perennial borders and meadows. Salix integra ‘Hakuro-Nishiki’ (dappled willow) is standing out in the landscape with its recent flush of white and pinkish foliage. Hydrangea macrophylla ‘Balimer’ (Endless Summer Hydrangea Shrub Series) are flowering. The Endless Summer SeriesTM of Hydrangea macrophylla was introduced to flower on both old and new wood. This year the Endless Summer series are the exception, having withstood the temperature fluctuations of this past winter/spring that caused major bud dieback on most other Hydrangea macrophylla (big leaf hydrangea).


Crabgrass (Digitaria spp.) has emerged. Yellow nutsedge (Cyperus esculentus) continues to thrive in mulched beds. Black swallowwort (Cynanchum louiseae) is flowering in unmanaged areas. Cedar-apple rust (Gymnosporangium spp.) is visible on Amelanchier spp. (serviceberry) fruit.

Metro West (Acton)

General Conditions:

The summer season is just right around the corner and many trees, shrubs, perennials, and annuals are in full bloom and filling the landscape with plenty of color. For the most part this past week, we’ve experienced pleasant yet wet days with moderate temperatures and cooler nights. Rain was recorded on 5 of the 7 days during this recording period, bringing our monthly total recorded precipitation to 2.18”. The historical monthly average rainfall for June is 3.93”. A high temperature of 82°F was recorded on both the 11th and 12th and a low temperature of 46°F was recorded on the 7th and 11th.


Rosa multiflora, an aggressive thorny invasive, is in full bloom and very easy to detect with its abundant single white flowers; it is seen throughout the landscape growing in, over, and amongst other trees and shrubs in the planted and/or wild landscape.

Central Region (Boylston)

General Conditions:

It’s been relatively cool for the start of summer, with temperatures topping out in the 60’s for the first four days of the reporting period. Although the sun was obscured by clouds or smoke for much of the period, we received very little precipitation. Smoke from the Canadian wildfires finally cleared out of the area after several days of poor air quality and some really fantastic sunsets. Much is in bloom throughout the landscape, including small trees like Kousa dogwood (Cornus kousa) and Japanese tree lilac (Syringa reticulata); shrubs like Virginia sweetspire (Itea virginica) and swamp azalea (Rhododendron viscosum); and perennials like wild geranium (Geranium maculatum) and ornamental onion (Allium spp. and cultivars).


Beech leaf disease was spotted on several American beech (Fagus grandifolia). Minor damage from viburnum leaf beetle was observed on arrowwood viburnum (Viburnum dentatum). Multiflora rose (Rosa multiflora) is in full flower. Dog ticks are active in abundance.

Pioneer Valley (Amherst)

General Conditions:

The unsettled weather that has dominated the first half of June continued over this past reporting period in the Pioneer Valley. Significant cloud cover (and wildfire smoke) persisted on many days while scattered showers occurred on 6/8, 6/9, 6/13 and 6/14. Once again, accumulations have mostly been minor to moderate. Dew points were on the rise on 6/13, providing a dose of summer humidity. While we have yet to receive a good soaking rain (at the time of writing), the scattered showers have provided some moisture and along with high temperatures largely in the 70s, plants are appearing green and lush. Turfgrass is mixed, with some areas looking green while others are starting to go dormant and brown out. We are still in the “goldilocks zone” or “honeymoon” period of the growing season, when plants are flaunting their vibrant new growth and the rigors of the growing season are not yet visible. As expected, there is an absolute horde of red maple seedlings emerging in the landscape right now. Red maples experienced a mast year, producing a prolific number of seeds. Impressively, this seed matures, disperses and germinates very quickly, producing seedlings early in the growing season with ample time to develop. According to the USFS Silvics Manual (Walters and Yawny, 1990), “Red maple can probably thrive on a wider range of soil types, textures, moisture, pH, and elevation than any other forest species in North America.” Seedlings of Japanese barberry and Oriental bittersweet are also abundant. Lightning bugs (or fireflies) can be observed in large meadows and residential landscapes where outdoor light pollution is limited. Tree pollen seems to be fading and white pines don’t appear to be producing as much as last year. 


Ensure newly transplanted trees and shrubs are receiving adequate irrigation. Some of the recent showers we have received appear to be sufficient but are only wetting the mulch layer. Continue to closely scout and examine plants for any early symptoms of insect feeding or disease while new growth is still tender. Rust symptoms are developing on rosaceous hosts. The most concerning is cedar-quince rust on serviceberry, hawthorn, and quince. At times, quince rust can also be very damaging to Juniperus, causing canopy dieback due to girdling twig and branch cankers. Sycamore anthracnose continues to keep mature trees looking very sparse. Beech and maple anthracnose symptoms continue to develop on young and mature trees. Invasive scarab beetles (Oriental, Japanese, Asiatic garden) are just starting or will be emerging soon depending on location. Japanese beetles tend to first appear around the 4th of July while Oriental and Asiatic beetles are a bit earlier. Black flies are still abundant in the valley bottom but their departure should be coming soon.

Berkshire Region (West Stockbridge)

General Conditions:

After a stretch of continued below normal temperatures, the weather took a turn on June 11 when temperatures at most sites through the county reached the 80s or nearly so. The high temperatures for the scouting period all occurred on that date with 83ºF in North Adams, 81ºF in Richmond, and 79ºF in Pittsfield. The low temperature at all these sites was reached on June 9: 41ºF in Richmond, 44ºF in Pittsfield, and 45ºF in North Adams. The forecast ahead appears to have temperatures at normal or slightly higher than normal. This should promote steady growth of plant materials. Also, on the plus side, the forecast calls for frequent rains starting today, June 14, and continuing to the weekend. This will provide a much-needed rain as soils had become quite dry and some plant materials were showing signs of drought stress. The combination of cool temperatures and dry weather had slowed plant development. Another serious factor in poor plant development continues to be a consequence of the hard freeze of May 18. Many perennial plants, both woody and herbaceous, have failed to bloom due to the death of flower buds. Turfgrass growth was a little retarded by the drought and on sites with sandy or coarse soils, sections of lawn were brown.


As mentioned above, the fallout from the May 18 hard freeze continues and is visible by the brown and withered foliage of many plants. No death to entire plants has been observed but the extent of browned foliage and dead flower buds is prominent on woody plants including Japanese maple, copper beech, American chestnut, magnolias, and some herbaceous perennials, notably hostas and Asian lilies. Disease pressures remain low, perhaps due to the dry weather up to this point. Leaf spots of maple, cedar apple rust, apple scab, and powdery mildew are common. Prominent pests are aphids on herbaceous plants, hydrangea leaf tier, rose slugs, adult lily leaf beetles, woolly beech aphid, elongate hemlock scale, hemlock woolly adelgid, and spongy moth. The latter pest population is much reduced from previous years and damage to date is mostly holes chewed in leaves as opposed to total defoliation. A major pest concern is deer ticks, a.k.a. black-legged ticks. Hardly anyone who works outdoors has escaped tick attachments. It is important to take all precautions to avoid these tick bites.

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 (BLD), caused by the foliar nematode Litylenchus crenatae ssp. mccannii, continues to expand in both incidence and severity across the Commonwealth. While the worst affected areas are in Essex, Middlesex, Suffolk, Norfolk, Plymouth and Bristol counties, BLD has been reported across the state. At present, the locally systemic nematicide fluopyram (Broadform and Luna Experience) may provide some level of control but uncertainty remains regarding the optimal time for application. The BLD nematode has overlapping generations, meaning that eggs, juveniles and adults may all be present in diseased foliage. Any time an organism has staggered development, chemical intervention must be timed correctly for maximum control. One recommendation is to make applications later in the growing season. The nematodes emerge from infested foliage and migrate to the buds that will produce next year’s growth from roughly late June into October. A later season application that targets the buds could theoretically ensure a lethal dose of fluopyram is present for nematodes that have already migrated and ones that will migrate. An alternative strategy is focused on making applications to the symptomatic foliage now, before the nematodes emerge from infested leaves to migrate. However, there is still uncertainty over whether fluopyram will kill the nematode eggs. This nematicide has efficacy against a wide array of plant parasitic nematodes, but for some, fluopyram does not kill the eggs. If applications are made now and the eggs survive, the treatment would not be fully effective.  

Branch flagging throughout the canopy of juniper trees (Juniperus sp.) due to cedar-quince rust (Gymnosporangium clavipes) and Diplodia twig canker (Diplodia sp.). Several trees, approximately 25-years-old, were symptomatic on a residential property on outer Cape Cod. The site includes full sun in sandy soils with drip irrigation. Over the past decade, these trees have shown scattered flagging throughout the canopy. The submitted branch segments all had swollen cankers that are the result of infection by G. clavipes. Microscopic evaluation also revealed that a Diplodia species was also present on the cankers and likely established as a secondary pathogen. Cedar-quince rust can be highly destructive on rosaceous hosts like hawthorn, quince and serviceberry, causing stem distortion and canopy dieback. Swollen, perennial cankers also develop on Juniperus species. Incredibly, the cankers often fail to kill the infected twig or branch, which allows the pathogen to persist in the canopy and produce spores from these perennial cankers each spring season. It’s a testament to the extreme hardiness of junipers. However, in extreme cases the cankers do girdle the infected branches and canopy dieback follows. The cankers can allow for additional fungi to invade, such as this case, with the establishment of Diplodia.

Cryptocline needle blight (Cryptocline taxicola) on a mature English yew (Taxus baccata). The tree is believed to be over 50-years-old and resides in a shaded setting with good loam soils. Last year, the area around the tree was converted into a play area with wood chips, resulting in moderate foot traffic from the construction. This spring, significant needle yellowing and premature shedding was observed, especially on interior portions of the canopy. Cryptocline needle blight is one of the few diseases of yews. The fungus attacks the needles and stems and typical symptoms include needle discoloration (orange to brown) and twig dieback. This discoloration of the needles differs from natural senescence, when older needles become yellow and are naturally shed.

Winter injury on Japanese holly (Ilex crenata) due to the early February arctic air mass. Several mature plants were injured in a pruned hedgerow at a residential landscape. The site includes full sun in loam soils with supplemental irrigation. This spring, scattered browning occurred throughout the canopies across the hedge. The leaves were pale green to brown and desiccated. While the twigs were killed, there was no evidence of any vascular stain that occurs when stem cankering pathogens are responsible. Overall, there was no indication of any disease or insects from the samples. Japanese holly appears to be one of the worst affected plants from the early February freeze event, in addition to flowering cherry, and numerous samples have been submitted to the UMass Plant Diagnostic Lab.

Dieback of a Japanese maple (Acer palmatum) due to poor root structure, possible freeze injury and twig/branch cankering by Botryosphaeria. The tree is approximately 10-years-old and has been present at the site for five years. It resides in full sun with drip irrigation in a planting bed adjacent to a driveway. The tree was slow to leaf out this spring with undersized foliage. Not long after the foliage was produced, leaves started prematurely shedding from the canopy. Girdling roots were discovered at the base of the trunk and the tree can be easily rocked back and forth, indicating poor root structure. The submitted branch segments were dry and had symptoms of cankering. After a brief incubation, spore-bearing pads of Botryosphaeria ruptured through the bark. It’s also possible the tree was injured by the early February freeze. Girdling roots are a common issue for container grown Japanese maples and if not corrected at the time of planting, this injury can manifest as canopy dieback several years later.

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

Insects and Other Arthropods

Citizen Science Opportunity: Reporting Native Ground Nesting Bees

The Cornell College of Agriculture and Life Sciences and the Cornell Atkinson Center for Sustainability and the Ground Nesting Bees Community Science Project are asking for your help collecting data on native bee populations and nesting sites. Your contributions will help scientists better understand the importance of native bees and how to protect them in our local environments.

What to Look For: Safely monitor ground nesting bees from early spring to late summer. Entrances in grass and soil are indicators of bee activity. Upload a photo of a bee entering or exiting its nest to iNaturalist (GNbee). To learn more, visit: and upload your photos here.

Some notes on safety: take appropriate precautions if you are allergic to bee stings. While many ground nesting bees or wasps do not sting, it is not a guarantee that you will not encounter a stinging species if participating.

Interesting Insects Reported or Seen Recently:

  • The oak leafrolling weevil has been spotted on swamp white oak in Hampshire County, MA as of 6/9/2023. In recent years, this insect has been active in Middlesex County, MA as well. (Photo courtesy of: Rich Parasiliti.) Oak Leafrolling Weevil: Synolabus bipustulatus (synonym Attelabus bipustulatus) is a small, stout, shiny, black weevil with two red spots, one on each elytra (hardened hindwing). (Another oak leaf rolling weevil species exists, Homoeolabus analis, but that insect is primarily orange in color with the exception of a black head and legs.) Weevils of this species (S. bipustulatus) are less than ¼ inch in size. The exact timing of this insect’s life cycle in Massachusetts is not completely understood. Adult weevils chew slits on either side of the midrib of the host plant leaf, where they will lay an egg at the tip of the leaf. The leaf is then folded (by the weevil) along the midrib and rolled into a tidy cylinder, kind of like a sleeping bag. By the end of this rolling, the egg is positioned near the center of the roll. Evidence of such leaf rolling was seen on oak in Middlesex County, MA on 5/12/2023. Since then, it has been again reported in Hampshire County, MA with adult weevils present and feeding on swamp white oak on 6/9/2023. (See image provided by Rich Parasiliti.) These weevils have been previously reported as active in Middlesex County in June of 2021. Once the egg hatches, the immature weevil larva (which is legless, curved, and plump with a brown head) feeds on the tissue inside the rolled leaf. Once the larva matures, it pupates inside the rolled leaf. Adults emerge again to continue the life cycle and there may be multiple generations per year in certain locations of this insect’s geographic range. Leafrolling weevils have been noted on 16 species of oak and 2 species of chestnut. These insects are rarely considered pests, as they typically do not cause noticeable damage to their host plants. Management is seldom considered necessary.

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.

*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).

Click here for more information about mosquitoes in Massachusetts.

EEE and WNV testing and tracking for this season began 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 14, 2023. Click here for more information.

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.

Click here for more information about mosquito repellents.

  • 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.

*Read more about the common name change for Vespa mandarinia.

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).

Spongy moth caterpillars have been observed molting and passing through different instars as they develop in Berkshire County, MA.

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? Read more 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.

Updates about spotted lanternfly egg hatch in Massachusetts are now available from MDAR at

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.

Spotted Lanternfly Fact Sheet

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

From the MA Department of Agricultural Resources (MDAR):

Spotted Lanternfly 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.

Adult Asian longhorned beetles typically begin to emerge from trees by July 1st in Massachusetts. By that time and throughout the rest of the summer, it is important to take photographs of and report any suspicious longhorned beetles to the Asian Longhorned Beetle Eradication Program phone numbers listed below.

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 Lonbghorned Beetle Eradication Program office in Worcester, MA at 508-852-8090 or toll free at 1-866-702-9938.

Report an Asian longhorned beetle find online or compare it to common insect look-alikes here.

  • White Spotted Pine Sawyer (WSPS): Monochamus scutellatus adults can emerge in late May throughout July, depending on local temperatures. 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 at . Additional information about this insect is provided by the MA Department of Conservation and Recreation at

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. Newly hatched and feeding bagworm caterpillars are small and less likely to be noticed. By late July and August, these caterpillars will be large and their feeding noticeable on individual trees and shrubs.
  • 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.
  • Cottony Taxus Scale: Pulvinaria floccifera, also referred to as the cottony camellia scale, utilizes such hosts as taxus, camellia, holly, hydrangea, Japanese maple, euonymus, magnolia, and jasmine, among others. Females have laid the long, narrow, white and fluted egg sac that makes them much more noticeable. Eggs will hatch over an extended period of 6 weeks and crawlers may be treated between 802-1388 GDD’s. This insect can cause the host to appear off-color. They also produce honeydew which promotes sooty mold growth. Dieback is not common with this insect. Target the underside of the foliage. Horticultural oil, neem oil, and insecticidal soaps may be used to manage these soft scales. Reduced risk options help preserve natural enemies.
  • 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.
  • 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.

  • 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.

  • 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.)
  • Fall Webworm: Hyphantria cunea is native to North America and Mexico. It is now considered a world-wide pest, as it has spread throughout much of Europe and Asia. (For example, it was introduced accidentally into Hungary from North America in the 1940’s.) Hosts include nearly all shade, fruit, and ornamental trees except conifers. In the USA, at least 88 species of trees are hosts for these insects, while in Europe at least 230 species are impacted. In the past history of this pest, it was once thought that the fall webworm was a two-species complex. It is now thought that H. cunea has two color morphs – one black headed and one red headed. These two color forms differ not only in the coloration of the caterpillars and the adults, but also in their behaviors. Caterpillars may go through at least 11 molts, each stage occurring within a silken web they produce over the host. When alarmed, all caterpillars in the group will move in unison in jerking motions that may be a mechanism for self-defense. Depending upon the location and climate, 1-4 generations of fall webworm can occur per year. Fall webworm adult moths lay eggs on the underside of the leaves of host plants in the spring. These eggs hatch in late June or early July depending on climate. Young larvae feed together in groups on the undersides of leaves, first skeletonizing the leaf and then enveloping other leaves and eventually entire branches within their webs. Webs are typically found on the terminal ends of branches. All caterpillar activity occurs within this tent, which becomes filled with leaf fragments, cast skins, and frass. Fully grown larvae then wander from the webs and pupate in protected areas such as the leaf litter where they will remain for the winter. Adult fall webworm moths emerge the following spring/early summer to start the cycle over again. 50+ species of parasites and 36+ species of predators are known to attack fall webworm in North America. Fall webworms typically do not cause extensive damage to their hosts. Nests may be an aesthetic issue for some. If in reach, small fall webworm webs may be pruned out of trees and shrubs and destroyed. Do not set fire to H. cunea webs when they are still attached to the host plant.
  • 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.
  • Hibiscus Sawfly: The larvae of the hibiscus (mallow) sawfly, likely Atomacera decepta, may be observed feeding on hibiscus hosts at this time. Sawfly larvae develop into wasp-like adults (Order: Hymenoptera) and therefore these “caterpillars” will not be managed by Bacillus thuringiensis var. kurstaki which is specific to the Lepidoptera (caterpillars that develop into moths or butterflies as adults). Reduced risk active ingredients such as spinosad are labelled for use against sawfly larvae. However, given that hibiscus are very attractive to pollinators, non-chemical management options such as hand picking and disposing of larvae, when possible, are best. Spinosad is toxic to pollinators until it dries. Click here for more information about the risks of insecticide active ingredients to pollinators.

The hibiscus (mallow) sawfly adult female uses her ovipositor to cut slits into leaf surfaces to deposit her eggs. Larvae emerge from these eggs and begin by first feeding on leaf undersides when small, and then move to feed on leaf surfaces as they grow in size. Only large leaf veins may be left behind if the population is large enough. Larvae have been observed moving to the base of the plant to pupate. Adults emerge and in some locations in the US, multiple generations have been recorded per year. This insect is known in the mid-Atlantic and Midwest states, but was reported feeding on Hibiscus spp. in Connecticut in 2004 and 2005 and has previously been reported in Massachusetts. The timing of the life cycle of this insect, as well as how many generations occur per year in Massachusetts, however, is not fully understood. Some research has shown that Hibiscus acetosella, H. aculeatus, and H. grandiflora seem to either exhibit some resistance to or tolerance of hibiscus sawfly feeding. In one study, all three had few if any eggs or larvae and were given the lowest damage rating among the species evaluated. This insect also does not feed on rose of Sharon or H. rosasinensis. It has, however, been reported to “voraciously” feed on H. moscheutos, H. palustris, H. militaris, and H. lasiocarpus.

  • 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.

  • 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.

  • 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.
  • 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 at
  • 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

Landscape Weeds

For identification of weed species noted below, refer to UMass Extension's Weed Herbarium:

Do not delay, treat garlic mustard, Alliaria petiolata, now. Second year plants are past flowering and seepods are visible. In most locations, the seedpods are still green, meaning the seed is not yet mature. Garlic mustard is a biennial and herbicide applications at this time of year will control second-year plants before they go to seed, as well as the first-year seedlings.

Many landscape trees commonly produce vegetative suckers at the base of trees. Suckers are commonly seen on crabapple, flowering cherry, flowering pear, plum, linden, maple and sometimes oak.  Honeylocust commonly produces vegetative sprouts along the entire length of the trunk. If these suckers or sprouts are not controlled, the landscape will be a contender for the “Shabby Landscape Award”. Pruning is effective but very time consuming. Another option would be used the product ScytheTM (pelargonic acid) to remove these vegetative suckers and sprouts when they are very small (very small means less than one inch in length or smaller). Pelargonic acid is a contact herbicide. When ScytheTM is applied to small suckers and sprouts, the product desiccates them and physical removal will not be required. Larger growth will first need to be physically removed and then ScytheTM can be used as a maintenance program. Products that contain glyphosate should not be used as glyphosate is a translocated herbicide and injury to the tree is possible.

Scout for weeds that may be creeping into landscape beds from adjacent turf areas. Use a non-selective herbicide to edge the bed.

Inspect areas of landscapes where new trees or shrubs, especially those that were field grown, have been planted in the last year. Look for perennial weeds that may be growing from the root ball. Canada thistle, mugwort, quackgrass, bindweed and horsenettle are some of the possible culprits. Perennial weeds can be spot treated with glyphosate-based products.

Tree seedlings are continuing to germinate in landscape beds, and some locations may have seedlings that are 2 to 4 inches tall. These seedlings can be treated with pelargonic acid (ScytheTM). Another option would be to cut these seedlings at the soil or mulch surface with a gas, electric, or battery-powered hedge shear. Organic/non-chemical products do not translocate and will not provide effective control of these young tree seedlings. Tree seedlings in turf areas will be controlled with mowing and an herbicide application is not necessary.

You may have noticed that a recent (May 18th) unseasonably cold night resulted in frost/freeze damage to Japanese knotweed, Polygonum cuspidatum or Fallopia japonica. As predicted in previous Landscape Messages, this injury has not killed knotweed and the plants have recovered nicely. Frost injury was more common in low lying areas. Injury was most apparent on the upper half of this season's new growth. Do not attempt to control Japanese knotweed in this early part of the growing season, as herbicide applications are not effective when applied now. In preparation for a late season herbicide application, cut or mow stands of knotweed to the ground in late May and early June. This practice is done to facilitate herbicide application by removing the dried stems from the previous year’s growth and decreases plant height so that the knotweed will be shorter at the time of treatment in late summer. There is also some indication that the plant’s carbohydrate reserves may be slightly reduced with this early season mowing.

In the last week, yellow nutsedge has become very apparent in landscape beds. Now is the time to treat yellow nutsedge. The best option is the translocated, non-selective herbicide glyphosate applied as a directed spray or wick application. In turf settings, halosulfuron can be applied. Applications should be completed by the third week in June.

Reported by Randy Prostak, Weed Specialist, UMass Extension Landscape, Nursery, & Urban Forestry Program

Additional Resources

Pesticide License Exams - The MA Dept. of Agricultural Resources (MDAR) is now holding exams online. For more information and how to register, go to:

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For a complete listing of landscape, nursery, and urban forestry program upcoming events, see our calendar at

For commercial growers of greenhouse crops and flowers - Check out UMass Extension's Greenhouse Update website.

For professional turf managers - Check out Turf Management Updates.

For home gardeners and garden retailers - Check out our home lawn and garden resources

Diagnostic Services

UMass Laboratory Diagnoses Landscape and Turf Problems - The UMass Extension Plant Diagnostic Lab is available to serve commercial landscape contractors, turf managers, arborists, nurseries and other green industry professionals. It provides woody plant and turf disease analysis, woody plant and turf insect identification, turfgrass identification, weed identification, and offers a report of pest management strategies that are research based, economically sound and environmentally appropriate for the situation. Accurate diagnosis for a turf or landscape problem can often eliminate or reduce the need for pesticide use. For sampling procedures, detailed submission instructions and a list of fees, see the Plant Diagnostic Laboratory web site.

Soil and Plant Nutrient Testing - The University of Massachusetts Soil and Plant Nutrient Testing Laboratory is located on the campus of The University of Massachusetts at Amherst. Testing services are available to all. The lab provides test results and recommendations that lead to the wise and economical use of soils and soil amendments. For more information, including current turn-around times, visit the UMass Soil and Plant Nutrient Testing Laboratory web site. The lab is currently accepting new orders for Routine Soil Analysis (including optional Organic Matter, Soluble Salts, and Nitrate testing), Particle Size Analysis, Pre-Sidedress Nitrate (PSNT), Total Sorbed Metals, and Soilless Media (no other types of soil analyses available at this time). Check for current turnaround time. Please plan for the fact that date of receipt in the lab is affected by weekends, holidays, shipping time, and time for UMass Campus Mail to deliver samples to the lab.

Tick Testing - The UMass Center for Agriculture, Food, and the Environment provides a list of potential tick identification and testing options at:

Acknowledgements: UMass Extension gratefully acknowledges the support of the following funding sources for the production of the Landscape Message –

  • The Massachusetts Nursery and Landscape Association Fund
  • The Massachusetts Department of Conservation and Recreation, Award #ISADCR28219926UMA22A
  • Stakeholders like you! The Landscape Message is partially supported by educational program user fees.