Landscape Message: May 27, 2022

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.

Wishing all a safe Memorial Day. The Landscape Message will be updated weekly in June. The next message will be posted on June 3. To receive immediate notification when the next Landscape Message update is posted, be sure to join our e-mail list 

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

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Scouting Information by Region

Environmental Data

The following data was collected on or about May 25, 2022. Total accumulated growing degree days (GDD) represent the heating units above a 50° F baseline temperature collected via regional NEWA stations (http://newa.cornell.edu) for the 2022 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	GDD		Soil Temp (°F at 4" depth)		Precipitation (1-Week Gain)	Time/Date of Readings
	1-Week Gain	2022 Total	Sun	Shade
CAPE	59  (268 BE)	188	60	56	0.42	12:00 PM 5/25
SOUTHEAST	85.5	281	76	60	0.26	3:00 PM 5/25
NORTH SHORE	72	229	60	52	0.03	9:30 AM 5/25
EAST	105	327	74	61	0.18	5:00 PM 5/25
METRO	111	305	58	54	0.13	6:30 AM 5/25
CENTRAL	112	291	61	57	0.33	7:00 AM 5/25
PIONEER VALLEY	114.5	314.5	64	59	0.85	12:30 PM 5/25
BERKSHIRES	95	248	62	55	1.01	7:45 AM 5/25
AVERAGE	94	273	64	57	0.40	_
* = information not available

As of 5/24, our state has moved into a "Moderate Drought" in some areas and the "Abnormally Dry" conditions have expanded west, approaching the Connecticut River:  Massachusetts | U.S. Drought Monitor (unl.edu)

Phenology

Indicator Plants - Stages of Flowering (BEGIN, BEGIN/FULL, FULL, FULL/END, END)
PLANT NAME (Botanic / Common)	CAPE	S.E.	N.S.	EAST	METRO W.	CENT.	P.V.	BERK.
Syringa meyeri (Meyer lilac)	Begin	*	Full	Begin	Begin	Begin	Begin/Full	Begin
Deutzia spp. (deutzia species)	Begin/Full	End	Full	Full	*	Full	Full	Begin
Aesculus hippocastanum (common horsechestnut)	Full	Full	Full	Full	Full	Full	Full	Begin
Enkianthus campanulatus (redvein enkianthus)	Begin/Full	*	Full	Full	Full	Full	Full	Begin/Full
Rhododendron carolinianum (Carolina rhododendron)	Begin/Full	Full/End	Full/End	Full	Full	Full/End	Full/End	Full
Rhododendron catawbiense (catawba rhododendron)	Begin/Full	Full	Full	Full	Full	Full	Full	*
Spiraea x vanhouttei (Vanhoutte spirea)	Full	Full	Full	Full/End	Full/End	Full	Full	Full
Elaeagnus umbellata (autumn-olive)	End	Full/End	Full/End	Full/End	Full/End	Full/End	Full/End	Full
Cornus florida (flowering dogwood)	End	End	Full/End	Full/End	Full/End	Full/End	Full/End	Full/End
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: The average temperature for the period from May 18 – May 25 was 59 ºF with a high of 81ºF on May 22 and a low of 41 ºF on May 25. The weekend was surprisingly warm, with Saturday in the mid 70s and Sunday reaching the low 80s. The period has been dominated by mostly sunny days. Less than half an inch of precipitation fell between two events, a little on May 19 and a little on May 22. The Cape area was listed as abnormally dry by the US Drought Monitor last week. (See the drought monitor link below the Environmental Data table above.) Soil moisture is short. Growth of unirrigated lawns has already slowed as a result of the abnormally dry conditions. Some herbaceous plants seen in bloom include bearded iris (Iris x germanica), columbine (Aquilegia spp), sundial lupine (Lupinus perennis), spotted geranium (Geranium maculatum), bloody or red geranium (Geranium sanguineum), chives (Allium schoenoprasum), and fringed bleeding heart (Dicentra eximia). Some woody plants seen in bloom include azaleas, rhododendrons, holly (Ilex opaca), doublefile viburnum (Viburnum plicatum), black chokeberry (Aronia melanocarpa), and even a couple of redbud (Cercis canadensis) still with a good flower display earlier in the week. Pollen is abundant and is primarily coming from white oak (Quercus alba).

Pests/Problems: Beech leaf disease (BLD) was reported from the Wood’s Hole area this week, the first reported occurrence in Barnstable County. Something to keep an eye out for. (See more about BLD in the Disease section below.) Winter moth is still feeding and can be found causing minor damage on a variety of woody plants: a fair amount were ballooning over the weekend. Viburnum leaf beetle was observed on arrowwood viburnum, eastern tent caterpillar on black cherry, boxwood leafminer is emerging from boxwood leaves, tip borer damage was seen on elderberry, and aphids were seen on sedum. Disease symptoms or signs observed during the period include needlecast on pitch pine, white pine needle disease on white pine, tip blight on eastern red cedar and Leyland cypress, branch dieback on Leyland cypress, anthracnose on sycamore, cedar apple rust galls active on eastern red cedar, Volutella blight on boxwood, leaf spot on hosta, basil downy mildew on basil, and red thread on turf. Environmental damage was observed on white pine over the weekend. The damage caused significant browning of foliage on some trees, damage was isolated to southern facing sides of trees. Hollies are going through natural needle loss. Slug and rabbit damages were observed. Ticks are everywhere – keep yourself protected. Weeds and invasive plants in bloom include yellow rocket (Barbarea vulgaris), thymeleaf speedwell (Veronica serpyllifolia), garlic mustard (Alliaria petiolata), cypress spurge (Euphorbia cyparissias), white clover (Trifolium repens), red clover (Trifolium pratense), narrowleaf plantain (Plantago lanceolata), creeping buttercup (Ranunculus repens), black medic (Medicago lupulina), bush honeysuckles (Lonicera spp.) and autumn olive (Elaeagnus umbellata).

Southeast Region (Dighton)

General Conditions: Although daytime temperatures have been quite variable, ranging between cool 50's weekdays to near 90 degrees over the weekend, dry high pressure has been dominant. The past week was the third without any significant precipitation. As a result local municipalities are already limiting outdoor watering and imposing bans on new irrigation system installations. Soils are dry. Many insects are quite active now such as beeflies, various crane flies, and fruitworm caterpillars. Some plants that were observed in flower are: Achillea millefolium (yarrow), Allium spp. (ornamental onion), Aquilegia spp. (columbine), Cerastium tomentosum (snow in summer), Coreopsis spp. (tickseed), Cornus kousa (Chinese dogwood), Cytisus scoparius (Scotch broom), Dianthus spp. (pinks, sweet William), Euphorbia spp. (spurge), Geranium macrorrhizum (prostate geranium), G. sanguineum (bloody geranium), Hesperis matronalis (dame's rocket), Kolkwitzia amabilis (beauty bush), Leucanthemum x superbum (shasta daisy), Lotus corniculatus (bird's foot trefoil), Lupinus spp. (lupine), Ornithogalum umbellatum (star of Bethlehem), Paeonia lactiflora (Chinese peony), Robinia pseudoacacia (black locust), Rosa rugosa (beach rose), R. 'knockout', Rubus fruticosus (brambles), Spiraea alba (meadowsweet), Syringa vulgaris (common lilac), S. x persica (Persian lilac), Tradescantia spp. (spiderwort), Trifolium pratense (red clover), T. repens (white clover), and Viburnum plicatum f. tomentosum (doublefile viburnum).

Pests/Problems: It's been a very dry spring with no end in sight. We have the benefit of very few apparent disease issues but may pay a steep price for lack of rain when higher temperatures arrive. (See the drought monitor link below the Environmental Data table above.) Despite the dry conditions, ticks remain an issue. In addition to taking the usual precautions during the workday be sure to check children and pets regularly. MDAR and others have been issuing warnings to be on the lookout for Spotted Lanternfly nymphs which should be hatched by now. Let's all be alert to this problem insect being moved on landscape materials before it negatively impacts our industry. (see SLF in Insect report below.) Pollen is very heavy, blanketing surfaces with a green/yellow cast and inducing sneezing/sniffling amongst those who are sensitive.

North Shore (Beverly)

General Conditions: Dry weather conditions and clear sunny skies persisted during this reporting period. Very little precipitation was recorded at Long Hill; approximately 0.03 inches of rainfall was recorded at Long Hill during the last seven days. (See the drought monitor link below the Environmental Data table above.) Temperatures were very seasonable for this time of the year. Daytime temperatures ranged from mid 50s to high 60s most of the days except for May 21 and 22 when temperatures climbed to 76ºF and 88ºF respectively. Nighttime temperatures ranged from mid 40s to mid 50s. The average daily temperature was 59ºF with the highest temperature of 88ºF recorded on May 22 and the lowest temperature of 44ºF recorded on May 25. Conditions were very conducive for outdoor activities and yard work. Lawns are green and there is plenty of color in the landscape. Recently planted trees, shrubs and perennials should also be watered. Woody plants seen in bloom include: many azaleas and rhododendrons, constellation Rutgers flowering dogwood (Cornus rutgersensis), handkerchief tree (Davidia involucrata var. vilmoriniana), common lilac (Syringa vulgaris), doublefile viburnum (Viburnum plicatum var. tomentosum), slender deutzia (Deutzia gracilis), wisteria (Wisteria floribunda), little leaf lilac (Syringa microphylla), sapphireberry (Symplocos paniculata), American cranberrybush viburnum (Viburnum trilobum), umbrella tree (Magnolia tripetala), mock orange (Philadelphus coronarius), pearlbush (Exochorda racemosa) and tree peony (Paeonia suffruticosa) . Herbaceous plants in bloom include: Scotch rose (Rosa spinosissima), Father Hugo rose (Rosa hugonis), columbine (Aquilegia canadensis), Japanese primrose (Primula japonica), doll’s eyes/white baneberry (Actaea pachypoda), Allium (Allium spp.) honesty plant (Lunaria annua), trillium (Trillium spp.) and fetterbush (Leucothoe fontanesiana).

Pests/Problems: Rose slug sawfly (Endelomyia aethiops) damage was observed on rose bushes. The larvae are still very small and they can easily be managed by insecticidal soap spray. Make sure to spray both sides of the leaves. Spinosad is also effective against sawfly larvae, whereas Btk is not. Note that spinosad is toxic to pollinators when it is wet, and should not be applied to blooming plants. Once the product has dried, it is no longer toxic to pollinators. Larvae of Viburnum leaf beetles (Pyrrhalta viburni) were observed on American cranberry viburnum and starting to cause damage on the leaves of this and other susceptible Viburnum cultivars. Control viburnum leaf beetle larvae before they become larger by applied spinosad or insecticidal soap or other registered pesticides. Weeds observed in flower include: dandelion (Taraxacum officinale), ground ivy (Glechoma hederacea), garlic mustard (Alliaria petiolata), deadnettle (Lamium purpureum), common chickweed (Stellaria media) and common groundsel (Senecio vulgaris). Mosquitoes and ticks are very active. Protect yourself with a repellent when working outdoors.

East Region (Boston)

General Conditions: The weather this past week fluctuated from several cool days in the 60’s to a sudden change with high humidity and a high temperature of 95ºF on May 22. We received a thunderstorm on the afternoon of the 22nd delivering gusty winds and 0.09” of precipitation. We have received a total of only 0.18” of precipitation over the past seven days. Many plants are in bloom: Aesculus x carnea ‘Briotii’ (red horse chestnut), Amsonia hubrichtii (Arkansas blue star), Cornus controversa (giant dogwood), Cornus x rutgersensis (Rutgers hybrid dogwood), Kolkwitzia amabilis (beauty bush), Nepeta spp. (catmint), Robinia pseudoacacia (black locust), Weigela spp. (weigela) and Wisteria spp. (wisteria). Rosa rugosa (beach rose) can be seen thriving and flowering in heat islands around town.

Pests/Problems: Lack of precipitation is an ongoing problem. We are currently in a 1.75 inch deficit. We are ranking in the top 10 driest springs. (See the drought monitor link below the Environmental Data table above.) The thunderstorm on the 22nd delivered 0.09 inches of precipitation and damaging winds resulting in downed limbs and trees. The cupping of boxwood foliage is an indication of the presence of boxwood psyllid (Cacopsylla buxi).

Metro West (Acton)

General Conditions: ​​We experienced some August-like temperatures during this reporting period. Humidity and temperatures soared with a high temperature of 97ºF recorded on the 22nd. There was little precipitation recorded during this week, a total of 0.13” was measured. The average monthly rainfall for May is 4.04” and as of the 24th, only 0.6” has been recorded for the month in this area. Despite the lack of rain, the landscape is exploding with color! In some stage of bloom this past week were the following woody plants: Aesculus × carnea 'Briotii' (red horse chestnut), Cornus x rutgersensis 'Ruth Ellen' (Rutgers hybrid dogwood), C. sericea (redosier dogwood), Leucothoe axillaris (coast leucothoe), Rhododendron spp. (rhododendron/azalea), Robinia pseudoacacia (black locust), Rosa rugosa (rugosa rose), Syringa spp. (lilac), and Viburnum plicatum var. tomentosum (doublefile viburnum). Woody vines in bloom include Lonicera sempervirens (trumpet honeysuckle) and Wisteria spp. (wisteria). Contributing even more color and interest to the landscape are some flowering herbaceous plants including: Ajuga reptans (bugleweed), Allium spp. (ornamental flowering onion), Amsonia hubrichtii (Arkansas blue star), Aquilegia spp. (columbine), Chrysogonum virginianum (green and gold), Dicentra spectabilis (old fashioned bleeding heart), D. spectabilis 'Alba' (white flowering old fashioned bleeding heart), Geranium maculatum (wild geranium), G. macrorrhizum (bigroot geranium), Hemerocallis spp. (early flowering daylily), Iris germanica (bearded iris), I. sibirica (Siberian iris), Nepeta spp. (ornamental catmint), Phlox divaricata (Canadian phlox), and P. stolonifera (creeping phlox).

Pests/Problems: The lack of any significant rainfall this spring and in this reporting area continues to be a real concern for our flora and fauna. (See the drought monitor link below the Environmental Data table above.)

Central Region (Boylston)

General Conditions: This reporting period featured some wild swings in temperature, from lows in the 40’s to highs in the mid-90’s. Weekend temperatures made gardening activities a struggle, especially for those of us who need a little more time to acclimatize to mid-summer temperatures and high humidity. In addition to wild temperature swings, we experienced prolonged heavy wind gusts, and the combination of wind and temperature led to the early demise of remaining tulips across the landscape. Many of our trees are fully leafed out at this point, and pollen counts are exceptionally high with oaks and pines flowering and releasing copious amounts of pollen. Much is in bloom throughout the garden, including Sibbaldiopsis tridentata (formerly Potentilla tridentata), commonly known as three-toothed cinquefoil, a wonderful shrubby groundcover in the rose family. With evergreen foliage, three-toothed cinquefoil is a fantastic option for dry, well-drained sites in full sun that will provide four seasons of interest, including mid-spring flowers that resemble small apple blossoms.

Pests/Problems: Pollen counts are very high, causing hay fever even in those who don’t suffer strong allergies. Dry conditions continue, with less than an inch of rain so far for the month of May. If this pattern continues, landscape plants will begin to show signs of drought stress. Newly planted trees and shrubs must be watered consistently for establishment and without natural rainfall, irrigation is critical. Adult pine sawyers are active, leading to many calls of concern that people have spotted Asian longhorn beetle. Although this lookalike insect resembles ALB, it is not a concern as a forest pest as it feeds on dead wood.

Pioneer Valley Region (Amherst)

General Conditions: As we get ready to settle into summer, we logged another week with erratic weather conditions in the Pioneer Valley. High temperatures ranged from 57–93ºF in South Deerfield over the course of only four days (5/19–5/22). Swampy heat typical of mid-summer smothered the region on 5/21 & 5/22, with dew points peaking near 70ºF and temperatures in the upper 80s to mid-90s in some locations. Mercifully, the heat was quickly cleared out by a strong cold front that brought some intense, but brief, rainfall during the evening of 5/22. Just prior to the advancing thunderstorms, potent wind gusts created a haze of pollen in the air and a swarm of oak catkins and red maple samaras came raining down. It was quite a sight. Most tender new growth withstood the heat and strong winds from the storm quite well. There were a lot of scattered debris and some downed limbs, but the vast majority of trees and shrubs appear unaffected. Overall, the landscape continues to amaze with flowering trees and shrubs, perennials/annuals in full flower and conifers with robust new growth. Upper soils are drying in some locations but the return to cooler temperatures has slowed plant water usage. Be mindful not to over irrigate newly installed trees and shrubs. Daily watering is not required when high temperatures are in the 70s and nights cool into the 50s. Waterlogged soils create anaerobic conditions that are harmful to roots.

Pests/Problems: Pine candles continue to elongate and new needles are actively growing. If you plan to treat both soft and hard pines for needle cast diseases, now is the time to begin. Regular applications will be required as the current season’s needles develop. Only minor spongy moth (Lymantria dispar) defoliation has been observed in western Hampshire County. While parts of eastern Hampden, Hampshire and Franklin Counties were badly defoliated during the ’17 & ’18 outbreak, much of the western valley and hill towns have avoided injury and appear to be spared of the current spongy moth outbreak happening in the far west of the state. Beech leaf disease (BLD) has been observed at several locations in southern Berkshire County. For those in Hampden County, carefully scout American and European beech for any symptoms of BLD as the advancing front makes its way north from CT. Specifically, look for dark-colored, interveinal banding and convex cupping when the foliage is viewed from above. As the disease establishes in an area, buds will become aborted and trees will produce fewer new shoots and foliage. Apple scab leaf spots and blotches are visible on infected trees. Some very minor shedding of interior canopy leaves was also observed. Pruning of interior canopy shoots and branches can help to reduce disease pressure by eliminating foliage that grows in full shade, which makes them more susceptible to infection.

Berkshire Region (Great Barrington)

General Conditions: Once again, weather took sharp turns over the past week, from a daytime high of 57ºF on May 19 to a near record setting high of 88ºF on May 21, followed by 87ºF on May 22. These temperature readings were recorded at the Pittsfield Airport. Following this brief heat spell, daytime high temperatures have dropped to the mid to upper 60s. Also, nighttime temperatures are currently in the upper 40s but that is going to change as the week progresses and temperatures begin to rise again but at a more gradual pace. The warmth has prompted plant growth; the forest landscape has gone from gray/brown to bright green with the rapid development of leaves. Rainfall as recorded at this West Stockbridge site was about one inch. Soil moisture level is good, resulting in steady but rapid growth of turfgrass. A late day thunderstorm on Sunday, May 22, brought with it some very high winds which resulted in numerous reports of fallen trees. However, this storm and resulting damage was pretty much confined to Pittsfield and north.

Pests/Problems: As temperatures rose and plant development accelerated, so have pests and some disease problems. Spongy moth caterpillar damage to tree foliage is more apparent, but the population and related damage seem to be localized. Most observations and complaints of heavy feeding by the caterpillars have been in the southern part of the County and along the New York State border. Other pests observed this week are: aphids on many woody and herbaceous plants, woolly beech aphid on copper beech, boxelder twig borer (egg stage), elongate hemlock scale (crawlers), lily leaf beetle (adults and larvae). A pest this scout has not seen before is the Canadian owlet moth caterpillar (Calyptra canadensis). It was found feeding on the foliage of Thalictrum (meadow rue). Diseases observed this week are apple scab and maple anthracnose. Black legged tick population remains high as do the incidences of 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

Diseases

TWO Upcoming Workshops on Eastern White Pine Health:

1. White Pine Health and the Impacts on Lumber Workshop on June 3 in Durham, NH. Presenters will walk you through assessing white pine health and defects in the forest, examining logs on the landing, and sawing lumber at the sawmill to see the impacts white pine disease, pests and defects have on lumber.

2. Eastern White Pine Management Institute Symposium on June 23–24 in Concord, NH. This two-day, in-person workshop will include seminars and field tours that will allow attendees to view the pests and pathogens affecting white pine with a range of forest health experts. Management strategies aimed at improving white pine health will be thoroughly reviewed.

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

• Beech leaf disease, caused by the foliar nematode Litylenchus crenatae ssp. mccannii on American beech (Fagus grandifolia) and European beech (F. sylvatica). Mature trees at different properties in southern Berkshire County, MA. The American beech is approximately 20” in diameter and has a moderate to severe case of beech leaf disease. It resides in a small group of trees and shrubs at a residential property, receiving full sun in moist, loam soils. Only a few leaves in the canopy were symptomatic and several other beech on the property were free of any noticeable symptoms. The European beech is roughly 30-years-old and was planted in full sun and has been otherwise healthy for several years now. As the disease becomes more established in future years, buds will be killed and the canopies will appear thin.
• Leaf spots and blotches on a Catawba rhododendron (Rhododendron catawbiense) caused by winter injury and two fungal pathogens (Pestalotiopsis and Phomopsis). The shrub is approximately 50-years-old and has been present at the site for 45 years. It receives a mixture of sun and shade with overhead irrigation in a landscaped bed. A marginal leaf blight along with brown and gray spots were observed throughout the canopy. Gray leaf blight of rhododendron is caused by Pestalotiopsis and this disease is common on rhododendrons suffering from winter injury. Leaf spotting/blotching by Phomopsis is not as common but can be regularly found throughout the landscape. Annual pruning of injured/diseased leaves and elimination of the overhead watering will help to alleviate disease pressure in the future.
• Armillaria root rot of rhododendron. The plant is young, less than 10-years-old and has been present at the site for only two years. The shrub was planted in full sun with drip irrigation in well-drained soils and has been otherwise cared for. One year after planting, wilting foliage and canopy dieback was observed. The submitted stem section exhibited decay (white rot) with rhizomorphs attached to the decaying wood tissue. Rhizomorphs are root-like structures produced by the fungus. They have a black, melanized outer rind that protects them from desiccation and attack by soil microbes. Rhizomorphs allow the fungus to spread within the soil and attack susceptible plants. While Armillaria root rot is typically a problem for established, mature plants, there are cases (such as this one), where young and recently transplanted trees and shrubs are attacked and killed by the fungus.
• Stem and branch cankering of white fir (Abies concolor) caused by Neonectria. The tree is roughly 15-years-old and has been present at the site for five years. It resides in a maintained landscape setting with full sun and drip irrigation. This spring, premature needle shedding was observed by the managing arborist. Upon closer examination, there were sunken cankers with oozing resin present on several small branches. Red-colored sexual fruiting bodies were detected on the submitted material and after a short incubation, there was an abundance of asexual sporulation from the cankered stems.

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

Insects

An Update about Neonicotinoid Use in Massachusetts:

Beginning July 1, 2022 systemic insecticide active ingredients known as neonicotinoids will become state restricted use for tree and shrub uses in Massachusetts. If an individual works in the commercial industry (landscapers, arborists, etc.), then a Commercial Certification License is needed. (Example: Category 36 Commercial Certification License, Shade Trees & Ornamentals.) Someone can use a state or federal restricted use pesticide if they have a Commercial Applicators License as long as they are working under the direct supervision of someone with a Commercial Certification. Unlicensed or uncertified individuals will no longer be able to apply neonicotinoids to manage insect pests of trees and shrubs in Massachusetts.

More information is available, here: https://www.mass.gov/service-details/pesticide-newsupdates

New, Helpful Information from Taryn LaScola-Miner, Director, Crop and Pest Services Division of the MA Department of Agricultural Resources:

“As you know, products that contain neonicotinoids and have certain use patterns will have a classification change from General Use to Restricted Use on July 1, 2022. In order to help inform the manufacturers, dealers, sellers and applicators of which products will be changing from general use to restricted use, the Department has created the list of neonicotinoid products that currently are and will become restricted use beginning July 1st. You may find the list at the link below. Please note that this list is subject to change.

Additionally, MDAR is anticipating that there will be more of a need for companies to follow the Direct Supervision regulations with this change. Therefore, MDAR has updated its Direct Supervision Frequently Asked Questions document as well.

Although an email will be sent to all licensed applicators within the next few weeks as a final reminder of the change, please pass this information along to your members and customers as an effort to make this transition as smooth as possible. If you have any questions, please let me know. Thank you!”

List of Neonicotinoid Products: https://www.mass.gov/doc/list-of-neonicotinoid-pesticides/download

Direct Supervision Frequently Asked Questions: https://www.mass.gov/doc/direct-supervision-frequently-asked-questions-faq/download

Interesting Insects Reported Recently:

• 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). The yellow poplar weevil was observed feeding on sassafras in Bristol County, MA on 5/24/2022 (images courtesy of Steve Antunes-Kenyon, MDAR). 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).

Insects and Other Arthropods

• Deer Tick/Blacklegged Tick: Ixodes scapularis adults are active all winter and spring, as they typically are from October through May, and “quest” or search for hosts at any point when daytime temperatures are above freezing. Engorged females survive the winter and will lay 1,500+ eggs in the forest leaf litter beginning around Memorial Day (late May). Larval and nymphal deer ticks may be encountered at this time. Larvae are encountered in New England from roughly May through November, with peak risk reported in August. Nymphs are encountered from April through July with a peak risk reported in June in New England. Nymphs may also be encountered again in October and November. For images of all deer tick life stages, along with an outline of the diseases they carry, visit: https://web.uri.edu/tickencounter/species/blacklegged-tick/ .

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: https://web.uri.edu/tickencounter/prevention/protect-yourself/

The Center for Agriculture, Food, and the Environment provides a list of potential tick identification and testing resources here: https://ag.umass.edu/resources/tick-testing-resources .

• 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: https://www.mass.gov/service-details/mosquitoes-in-massachusetts

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: https://www.mass.gov/service-details/mosquito-repellents and https://www.cdc.gov/mosquitoes/mosquito-bites/prevent-mosquito-bites.html

 

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

Invasive Insects & Other Organisms Update:

• Spongy Moth: Lymantria dispar egg hatch was first reported to UMass Extension by arborists in Great Barrington, MA on 5/5/2022.Since then, the MA Department of Conservation and Recreation has seen eggs hatching in parts of Williamstown, Hancock, Pittsfield, Erving, and Wendell, MA (reported on 5/12/2022). Since then, the MA Department of Conservation and Recreation has seen activity in parts of Williamstown, Hancock, Pittsfield, Erving, and Wendell, MA (reported on 5/12/2022). Additionally, arborists report caterpillar feeding activity in Sheffield, MA. At that location, heavy feeding has been observed on apples (with variation depending on variety) and oak as well as light feeding on Prunus spp., Crataegus spp., and Tilia americana. Light to no defoliation was observed in Sheffield, MA on mulberry, Katsura, hydrangea, pear, Cercis canadensis, and Viburnum nudum. Professionals and property owners working and living in Berkshire County continue to be on high alert as they monitor and manage spongy moth caterpillar feeding. At this time, the caterpillars are still small in size, but by the end of June the extent of their defoliation in western MA should be very apparent as the caterpillars grow in size.

If high-value specimen trees in Berkshire County are currently being defoliated by young spongy moth caterpillars, consider applying the reduced risk insecticide Bacillus thuringiensis Kurstaki (Btk) to host plant leaves at this time while caterpillars are still small and actively feeding, but before caterpillars are over ¾ inch in length. Spinosad is an additional reduced risk active ingredient for the management of spongy moth caterpillars. Once spongy moth caterpillars are large (2-3 inches in length) and very noticeable, they are very difficult to manage and will have already done much of their feeding. It is preferable to treat the early instar caterpillars, if chemical management is deemed necessary on ornamental plants in the landscape. Keep in mind that most healthy trees can survive a single year of defoliation, if they do not have other stressors. Specimen trees that were defoliated last year in Berkshire County, that have caterpillars feeding on them again this year, should be prioritized.

Why did the common name for Lymantria dispar change recently? More information is available here: https://entsoc.org/news/press-releases/spongy-moth-approved-new-common-name-lymantria-dispar .

• 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: https://massnrc.org/pests/linkeddocuments/SLFChecklistForResidents.pdf .

Take the new spotted lanternfly egg mass identification quiz from MDAR! Available here: bit.ly/SLFEggMassQuiz .

Spotted lanternfly eggs are reported to have hatched in southern Connecticut last week, marking the start of the activity of the nymphs. SLF eggs are expected to hatch in Massachusetts, if they are here, within the next week or two.

The MA Department of Agricultural Resources (MDAR) recently published the following press release, urging professionals and the general public to search all nursery stock, particularly maples and crabapples, purchased this year for spotted lanternfly egg masses: https://www.mass.gov/news/state-agricultural-officials-ask-public-to-be-on-alert-for-hatching-of-invasive-spotted-lanternfly-eggs . In particular, the press release warns:

“MDAR recently received reports that nursery stock from SLF-infested areas may have been sent to Massachusetts growers. Due to this, anyone who has recently purchased trees or shrubs or had them planted on their property, particularly maple or crabapple trees, is being asked to inspect the trunk and branches to ensure there are no SLF egg masses or any hitchhiking nymphs, and to report any finds to MDAR. Landscapers and plant nurseries are also being reminded to stay on the lookout for this pest.”

Currently, the only established populations of spotted lanternfly in Massachusetts are in a small area in both Fitchburg and Shrewsbury, 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: https://massnrc.org/pests/slfreport.aspx . If you are living and working in the Fitchburg and Shrewsbury areas, please be vigilant and continue to report anything suspicious.

For More Information:

From UMass Extension:

Check out the InsectXaminer Episode about spotted lanternfly adults and egg masses! Available here: https://ag.umass.edu/landscape/education-events/insectxaminer

Fact Sheet: https://ag.umass.edu/landscape/fact-sheets/spotted-lanternfly

From the MA Department of Agricultural Resources:

Fact Sheet and Map of Locations in MA: https://massnrc.org/pests/pestFAQsheets/spottedlanternfly.html

• 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: http://massnrc.org/pests/albreport.aspx or https://www.aphis.usda.gov/pests-diseases/alb/report .

• Browntail Moth: Euproctis chrysorrhoea is an invasive insect originating from Europe and first detected in the US in Somerville, MA in 1897. Currently, browntail moth is limited to a small portion of eastern Massachusetts, particularly areas near the coast.  Report suspected browntail moth life stages here: https://massnrc.org/pests/pestreports.htm . Due to a persistent outbreak of this insect in Maine since approximately 2016, it is a good idea for us to again familiarize ourselves with this pest. (For more information and the latest updates about the status of this insect in Maine, visit: https://www.maine.gov/dacf/mfs/forest_health/invasive_threats/browntail_moth_info.htm .)

Caution: hairs found on the caterpillar and pupal life stages of this insect can cause a rash similar to poison ivy. Some individuals are very sensitive to browntail moth hairs and may also experience allergic reaction. The chance of interacting with browntail moth hairs increases between May and July, although they could be a problem at any time of year.

The larval or caterpillar stage of this insect is present from August until the following June (spending the winter in webs they create on the tips of host plant twigs). In the fall, groups of caterpillars are found creating webs around a tightly wrapped leaf (covered in bright white silk) where they will overwinter in groups of 25-400. These 2-4 inch long webs can be found on the ends of branches often on apple or red oak. As soon as leaves begin to open in the spring (usually by April), the caterpillars will crawl from their webs to feed on the new leaves. Caterpillars are fully grown around June and spin cocoons in which they pupate. These cocoons are also full of the irritating hairs and should be dealt with extreme caution. Adult moths emerge in July and females lay eggs on the undersides of leaves in masses of 200-400, covering them with hairs from their bodies. (Adults do not typically cause skin rashes.) Eggs hatch around August and September and larvae feed shortly before forming their overwintering webs.

The primary concern with this insect are the poisonous hairs found on the caterpillars. Contact with the caterpillar or its hairs can cause a rash similar to poison ivy in susceptible individuals. If hairs break off and blow around in the wind, they can cause difficulty breathing and headaches. While this insect can act as a defoliator in the larval stage, feeding on the leaves of many deciduous trees and shrubs, this activity may be secondary to concerns about public health risks. Care should be taken to avoid places infested with these caterpillars, exposed skin or clothing should be washed, and the appropriate PPE should be worn if working with these insects. Consult your physician if you have a reaction to the browntail moth.

• 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: https://ag.umass.edu/fact-sheets/emerald-ash-borer . Additional information about this insect is provided by the MA Department of Conservation and Recreation, here: https://storymaps.arcgis.com/stories/b60f63199fa14805a8b9f7c82447a25b .

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. For an update about the progress of the biological control of emerald ash borer, visit Dr. Joseph Elkinton’s archived 2022 webinar now available here: https://ag.umass.edu/landscape/education-events/invasive-insect-webinars .

• Hemlock Woolly Adelgid: Adelges tsugae (HWA) is present on eastern and Carolina hemlock. The overwintering hemlock woolly adelgid generation (sistens) is present through mid-spring and produces the spring generation (progrediens) which will be present from early spring through mid-summer. HWA, unlike many other insects, does most of its feeding over the winter. Eggs may be found in woolly masses at the base of hemlock needles beginning in mid-March. Each woolly mass is created by a female who may then lay 50-300 eggs. Hemlock woolly adelgid eggs were observed in samples collected in Amherst, MA on April 13, 2022. Eggs hatch and crawlers may be found from mid-March through mid-July.

Nicole Keleher, Massachusetts Department of Conservation and Recreation (DCR) and the Director of their Forest Health Program, reports some curious observations about the hemlock woolly adelgid population in Massachusetts this year. Out of 17 sites across the state that they monitored for HWA winter mortality, they averaged approximately 47% mortality of the adelgid over the winter. This is relatively low, in the context of recent year’s winter mortality. The 17 sites had adelgid winter mortality that ranged from 23% to 80% of the insects sampled, but most sites were in the 40-50% range – providing us with the 47% average. Given those percentages, and the fact that these insects reproduce parthenogenetically (females lay viable eggs without mating), MA DCR notes that they are seeing lower than expected densities of HWA right now. Anecdotally, they suspect this may be because of mortality in the spring progrediens generation, rather than the more typical winter mortality of the sistens generation. What is the reason for this? We are uncertain. Anecdotally, it also seems that hemlock woolly adelgid populations in western MA may be higher this season than those in eastern MA. Again, the reasons for these observations are currently unknown, and this information should be considered mostly anecdotal at this time.

What does all of this mean for hemlock woolly adelgid management this season? I am not sure. Perhaps trees in eastern MA may experience a bit of a reprieve from this insect in 2022, whereas those in western MA may not. However, as DCR notes there is site variability with their observations – so this information cannot be applied for every scenario. The important thing is to monitor specimen hemlock trees and shrubs in managed landscapes and make management decisions based on site-specific observations and historical recordkeeping at each individual location.

• 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) that are impossible to remove. The first adults appear in the end of May – June, but the numbers are low and infestations are rarely noticed at that time. It is easy to misidentify earthworms if only immatures found. By August and September, this is when most observations of fully mature jumping worms occur. At that time, snake worms become quite abundant, infestations become very noticeable, and may cause a lot of concern for property owners and managers.

For More Information:

UMass Extension Fact Sheets:

Earthworms in Massachusetts – History, Concerns, and Benefits: https://ag.umass.edu/landscape/fact-sheets/earthworms-in-massachusetts-history-concerns-benefits

Jumping/Crazy/Snake Worms – Amynthas spp.:

https://ag.umass.edu/landscape/fact-sheets/jumpingcrazysnake-worms-amynthas-spp

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

https://ag.umass.edu/news-events/highlights/jumping-worms-conference

 

Tree & Shrub Insect Pests, Continued:

• 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 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: 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. Now is the time to scout for and remove and destroy overwintering bags. More information can be found here: https://ag.umass.edu/landscape/fact-sheets/bagworm   A note about bagworms: there are approximately 28 different species of bagworm moths in North America belonging to the family Psychidae. The larvae of the common bagworm (T. ephemeraeformis) is not active right now, but other species may be.

• Black Turpentine Beetle: Dendroctonus terebrans adults may begin to be active between mid-April to mid-May. Host plants include: black pine (Pinus thunbergiana), eastern white pine (Pinus strobus), Japanese black pine (Pinus thunbergii), loblolly pine (Pinus taeda), pitch pine (Pinus rigida), red spruce (Picea rubens), Scots pine (Pinus sylvestris), and slash pine (Pinus elliottii).

This is one of the largest native North American bark beetles. In the northern parts of its extensive range, the black turpentine beetle overwinters as an adult in the bark of its hosts. In the southern portions of its range, all life stages may be present throughout the year. Egg laying and feeding is usually kept to the basal 6 feet of the host plant. Mated pairs of adult beetles work to excavate galleries that may be 9.8 inches wide and 11.8 inches long. 100-200 eggs may be laid on one side of the gallery. Once hatched, larvae feed in groups on the inner bark. Fully grown larvae are legless, white, and almost 1/2 inch in length. Pupation occurs and adults eventually emerge from the bark to re-infest the same tree, or disperse to another susceptible host.

Stumps and buttress roots of freshly cut trees are favored by this insect. Attacked trees may exhibit browning of needles and oozing of large masses of pitch. Masses of pitch (pitch tubes) may cover holes in the trunk and may be considerably larger than those of southern pine beetle. Pitch hardens and is first white but may turn red as it ages. Pitch is irregular in shape and up to 1.6 inches in diameter. Pitch tubes are not visible when the area below the soil line is attacked. Healthy trees are usually not attacked, however it has been reported on occasion.

Check drought-stressed or otherwise stressed trees for needles turning light green to rust color. Check the lower 6 feet, particularly the lower 18 inches of the trunk for 1.6 inch in diameter pitch tubes or small entrance holes from the adults. Reddish-brown boring dust may be found near the base of the tree as well.

• 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. If installing new boxwoods, resistant cultivars such as ‘Vardar Valley’ and ‘Handsworthiensis’ are good choices at sites where this insect has been a problem.

• 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. 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.

• Cankerworms: Alsophila pometaria (fall cankerworm) and Paleacrita vernata (spring cankerworm) are often confused for winter moth (Operophtera brumata). Cankerworm populations in eastern MA, particularly on areas of Cape Cod, were confused for winter moth in 2019. Spring cankerworm adults are active in February and March, and fall cankerworm adults are active in late November into early December. During these times, both species lay eggs. These native insects most commonly utilize elm, apple, oak, linden, and beech. Eggs of both species hatch as soon as buds begin to open in the spring. Caterpillars occur in mixed populations and are often noticeable by mid-May in MA. Young larvae will feed on buds and unfolding leaves. There are two color forms (light green and dark) for caterpillars of both species. Like winter moth, they will drop to the soil to pupate. This usually occurs in June. Fall cankerworm larvae have three pairs of prolegs (one of which is small so it is sometimes referred to as ½) and spring cankerworm have two pairs. (Winter moth caterpillars also have 2 pairs of prolegs.) If populations are large and damage is noticeable on hosts, reduced risk insecticides such as Bacillus thuringiensis Kurstaki or spinosad may target larvae between approximately 148-290 GDD’s.

• Copper Underwing/Humped Green Fruitworm: Amphipyra pyramidoides adults are moths referred to as copper underwings. Their caterpillars are often lumped into the “fruitworm” common name with additional species, in this case commonly referred to as the “humped green fruitworm”. Blue-green caterpillars have creamy spots and a noticeable hump on abdominal segment number 8. A white and yellow stripe can be seen intersecting the spiracles (the external respiratory openings) of the caterpillar. Caterpillars may reach 4.5 cm. long and are found feeding on apple, basswood, blueberry, cherry, chestnut, elm, grape, greenbrier, hawthorn, hickory, lilac, maple, oak, poplar, rhododendron, viburnum, walnut, and others. Mature caterpillars are found in May and June. This humped green fruitworm was found feeding on elm on 5/24/2022 in Hampshire County, MA. Caterpillars can often be seen raising their rear ends when on leaves (this behavior was observed with this insect) which may remind one of a sawfly caterpillar when attempting to identify (don’t forget to check the number of prolegs; this caterpillar has 5 pairs, whereas most sawflies have 6 or more pairs). Humped green fruitworms tend to move away from the leaves that they have been feeding on, a tactic that helps them avoid predatory birds who focus on damaged leaves to find their prey. This tactic also helps deter the observant human who may be searching for the cause of defoliation. By September, adult moths become reproductively active and females lay eggs into November. The egg stage overwinters. There is one generation per year (Wagner, 2005).

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 most 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). Additional species in the genera Lithophane and Orthosia are sometimes also referred to collectively as “fruitworms”.

• 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 are 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.

• 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.

 

• 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: https://ag.umass.edu/landscape/education-events/insectxaminer

• 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. (Eggs begin to hatch in early June.)

• 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. Overwintered second instar nymphs can be targeted between 38-148 GDD’s, base 50°F. 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.

• 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.

 

• 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.

• Holly Leafminers: Seven species of leaf miners feed on holly. Phytomyza ilicicola is usually referred to as the native holly leafminer. This species is known to feed on Ilex opaca, I. crenata, and related cultivars; however, it only lays its eggs in American holly (Ilex opaca). Some research suggests that the native holly leafminer may lay its eggs in other Ilex species, but that the larvae are unable to complete their development. This insect is found throughout the native range of its host plants. Larvae overwinter in leaf mines and pupation occurs in March and April and adult emergence by mid-May (192-298 GDD’s, base 50°F). Adult flies are known to emerge over a period of 6 or so weeks in the spring. Females lay eggs using their ovipositor on the underside of newly formed leaves. A tiny green blister forms on the leaf as the first symptom of injury. Larvae hatch from the egg and create a narrow mine that may appear brown from the upper leaf surface. Mines are broadened in the fall and a large blotch is completed in the winter. Larvae are yellow maggots and reach 1.5 mm. in length when mature. Current year’s mines are easily overlooked due to the slow feeding patterns of the larvae. Premature leaf drop may occur. Remove and destroy mined leaves before May. Phytomyza ilicis is usually only referred to as the holly leafminer, and it is a non-native species introduced from Europe and only feeds on Ilex aquifolium. (The native holly leaf miner does not develop in I. aquifolium.) The biology and damage this insect causes is similar to that of the native holly leafminer, with the exception of the fact that eggs are laid in the midvein of the leaf and young larvae tunnel in the vein until the fall. Remove and destroy mined leaves before May. Adults may be present mid-late May (246-448 GDD’s, base 50°F).
• 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 buds 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. Hydrangea leaftier activity was seen on 5/15/2022 in Pittsfield, MA. Many envelope or purse-like structures were seen throughout the plants and could be found from the base to the top of the plant. By gently pulling apart the tied-together leaves, tiny caterpillars were 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: 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 multiple years of feeding from this insect, and foliage will appear brown. Repeated yearly feeding can occasionally 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: https://ag.umass.edu/landscape/education-events/insectxaminer

• Lacebugs: Stephanitis spp. lacebugs such as S. pyriodes can cause severe injury to azalea foliage. S. rhododendri can be common on rhododendron and mountain laurel. S. takeyai has been found developing on Japanese andromeda, leucothoe, styrax, and willow. Stephanitis spp. lace bug activity should be monitored through September. Before populations become too large, treat with a summer rate horticultural oil spray as needed. Be sure to target the undersides of the foliage in order to get proper coverage of the insects. Certain azalea and andromeda cultivars may be less preferred by lace bugs.

• 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 are 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 insect may be targeted between 200-299 GDD’s, base 50°F.

• 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.) 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: https://ag.umass.edu/landscape/education-events/insectxaminer

• 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. 
• Oak Apple Galls: Several species of gall wasps cause structures referred to as oak apple galls. This oak apple gall (Amphibolips spp.) was observed on 5/24/2022 in Hampshire County, MA. A common species mentioned in Johnson and Lyon (1991) is Amphibolips confluenta, which forms large galls that are attached to the midrib or petiole of oak leaves. Additional species in this genus are known to cause oak apple galls, including A. quercusinanis and A. quercusspongifica. A. confluenta galls are filled with a spongy mass that may be cut with a knife. A single wasp larva is found within a hard, seed-like cell in the center of the gall. As the gall dries, the spongy interior becomes a mass of fibers radiating from this central cell to the thin shell of the gall. These galls do no damage to their host plants and do not require management. Not enough is known about gall forming insects, and there is so much to learn!
• 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.

• Snowball Aphid: Neoceruraphis viburnicola eggs overwinter on viburnum twigs and buds. Eggs hatch and this aphid becomes active on certain species of viburnum roughly between 148-298 GDD’s or around redbud bloom. This insect is particularly noticeable on V. opulus, V. prunifolium, and V. acerifolia. Stem mothers, appearing blueish-white, can be found in curled up and distorted foliage. Damage caused by this insect pest is mostly aesthetic.

• 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. Be sure to also scout for predatory mite adults and eggs which can help regulate spruce spider mite populations. Avoid broad spectrum chemical management options that kill predatory mite populations, often making spruce spider mite outbreaks worse.

• 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.

• Viburnum Leaf Beetle: Pyrrhalta viburni is a beetle in the family Chrysomelidae that is native to Europe, but was found in Massachusetts in 2004. Viburnum leaf beetle overwinters as eggs laid in capped pits on the newest growth of susceptible viburnum branches. Scout for overwintered eggs and prune out and destroy before they hatch. Egg hatch occurs in late-April to early-May as temperatures warm and foliage becomes available. Monitor for larvae in mid-May (80-120 GDD’s). 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 http://www.hort.cornell.edu/vlb/ .

• 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.

• Woolly Apple Aphid: Eriosoma lanigerum may be found on apple, crabapple, hawthorn, mountain-ash, Pyracantha, and elm hosts. The primary (winter) host is elm, on which aphids infest emerging spring leaves, causing leaves to curl or close into stunted, rosette-like clusters found at twig tips. On apple and crabapple, this species of aphid colonizes roots, trunks, and branches in the summer and is commonly found near previous wounds or callous tissue. On roots, the aphids cause swelled areas which can girdle and kill roots. The aphids, when found in above ground plant parts such as elm leaves, are covered with white wax. Eggs are the overwintering stage on elm, which hatch in the spring in time for the nymphs to infest new elm foliage. Following a few generations on elm, the aphids will develop into a winged form, which will disperse and seek out apple and crabapple. Multiple generations will occur on these alternate hosts in the summer and by the fall, a winged form will return to elm and mated females will lay eggs near elm buds. These aphids are a favorite snack for insect predators such as the multicolored Asian lady beetle, Harmonia axyridis. Elm can withstand multiple years of woolly apple aphid infestation and this insect is primarily aesthetic in its impact to trees. Management may not be necessary.

• Woolly Elm Aphid: Eriosoma americanum females lay a single egg in the cracks and crevices of elm bark, where the egg overwinters. Eggs hatch on elm in the spring as leaves are unfolding. Aphids may be active from 121-246 GDD’s, base 50°F on elm. A young, wingless female hatched from the egg feeds on the underside of leaf tissue. This female aphid matures and gives birth to 200 young, all females, without mating. These aphids feed, and the elm leaf curls around them and protects them. By the end of June, winged migrants mature and find serviceberry hosts. Another set of females is produced. These new females crawl to and begin feeding on the roots of serviceberry. Multiple generations occur on the roots of serviceberry through the summer. Elm can withstand multiple years of woolly elm aphid infestation and this insect is primarily aesthetic in its impact to trees. Management may not be necessary. Lady beetle larvae and adults often feed on these insects.

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: http://massnrc.org/pests/pestreports.htm .

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

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