Just a Friendly Reminder:
At this time, as always, it is important to remember that not all eggs we encounter in the landscape are from insect pests of trees and shrubs. They may be from helpful predators, such as the yellow eggs of the multicolored Asian lady beetle seen on the bark of this European hornbeam, as observed on 5/22/19 in Amherst, MA. This particular beetle is an important predator of certain aphids and scale insects and was originally introduced into the United States as a biological control agent. However, as we know, with this particular insect the legacy has been a bit of a double-edged sword. While it can be an important predator of pest insects, adults seek shelter in more comfortable areas for the winter - such as our homes - and their presence can be a nuisance to some (particularly when they come inside in large numbers). But at this time of year, we can enjoy the benefits of their impact on common landscape pests.
Woody ornamental insect and non-insect arthropod pests to consider, a selected few:
- Gypsy Moth:(Lymantria dispar) host plants include but are certainly not limited to oak (favored), maple, birch, poplar, and many others. Gypsy moth caterpillars were observed on elm and oak in Amherst, MA on 5/21 and 5/23/19. Late 2nd and early 3rd instar caterpillars were seen. During the day, 2nd instar caterpillars can be found feeding on the leaves of susceptible hosts, while the 3rd instar caterpillars may be seen (if local populations are in relatively low densities) gathered in groups on areas of the trunk or branches. In high populations, this daytime hiding behavior stops and older caterpillars will still be seen feeding on the leaves. Anecdotally, at this time, gypsy moth caterpillar densities on host plant leaves in certain areas, such as parts of Amherst, are lower than what was expected given the number of overwintering egg masses. While we have had reports of caterpillar activity and feeding across the state, we suspect that an early mortality event (that cannot yet be explained) may have occurred. While this is certainly excellent news, we should remain cautiously optimistic and continue to monitor gypsy moth populations and feeding damage, particularly in the areas mentioned below in the 2018 overwintering egg mass survey conducted by MA DCR.
Despite the fungal outbreak that swept through the 2017 caterpillar population, some lucky caterpillars survived to pupation and emerged as adult moths. (However, adults were present in 2017 in far fewer numbers than would have existed without the fungus.) In 2018, the Massachusetts Department of Conservation and Recreation (DCR) reported that approximately 159,705 acres were defoliated by gypsy moth caterpillars in pockets across the state. While this may seem negligible in comparison to the 923,186 acres of defoliation due to gypsy moth in 2017, for many communities the impact was still significant. MA DCR also surveyed multiple locations across the state for overwintering gypsy moth egg masses in December of 2018. They provide a map of their predictions of where pockets of defoliation may occur in 2019 based on the densities of egg masses they observed in monitored areas across the state. Many of these areas correspond with the locations previously defoliated by gypsy moth caterpillars in 2018. MA DCR predicts gypsy moth activity will occur this season in regionalized pockets of Essex, Hampden, Hampshire, Middlesex, Norfolk, Plymouth, and Worcester Counties. Maps of previous year’s defoliation as well as the 2018 overwintering gypsy moth egg mass survey may be found here, courtesy of the MA DCR: https://www.mass.gov/guides/gypsy-moth-in-massachusetts .
While it is very difficult to predict how much defoliation Massachusetts will see in 2019 due to gypsy moth caterpillar feeding, we can be certain that in areas where many egg masses overwintered, pockets of defoliation could still occur in certain areas of the state this year.
- Winter Moth: (Operophtera brumata) The winter moth population in eastern Massachusetts continues to be at record lows in most locations, and Dr. Joseph Elkinton, Professor of Environmental Conservation at the University of Massachusetts, is declaring victory over this pest! In case you have missed this news from last year, a recent edition of the UMass Magazine discusses the winter moth story and successes with the biological control of this insect (along with some fun and excellent illustrations): https://www.umass.edu/magazine/spring-2019/winter-moth .
See the Regional Reports above for current updates. Pupation of winter moth caterpillars typically occurs in late May/early June in Massachusetts, depending upon the location. Coastal areas including Cape Cod are usually a week or two behind more inland locations. Upon maturity, winter moth caterpillars will be approximately one inch in length and drop to the soil to pupate. Once pupation occurs, management of winter moth is no longer feasible.
Be sure that management of winter moth is necessary by monitoring for damaging populations before making applications in landscape settings. There may be some locations where winter moth caterpillars can be found while Cyzenis albicans catches up with the population. For more information about the life cycle and management of winter moth, please visit this fact sheet: Winter Moth Identification and Management https://ag.umass.edu/landscape/fact-sheets/winter-moth-identification-management .
Winter moth is a non-native insect that was identified in Massachusetts for the first time in 2003 following persistent reports of defoliation in eastern areas of the state such as Cape Ann and on the North Shore near Cohasset, Hingham, and Rockland on the South Shore in the late 1990’s. For more detailed information about the history of this insect pest in North America and Massachusetts, please visit this fact sheet: Winter Moth in Massachusetts: History and Biological Control https://ag.umass.edu/landscape/fact-sheets/winter-moth-in-massachusetts-history-biological-control .
- 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 miles2 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 .
- Deer Tick/Blacklegged Tick: Check out the archived FREE TickTalk with TickReport webinars available here:https://ag.umass.edu/landscape/education-events/webinars . The next live webinar will be held on October 9, 2019 with Dr. Stephen Rich of the UMass Laboratory of Medical Zoology. Previous webinars including information about deer ticks and associated diseases, American dog ticks and lone star ticks and associated diseases, ticks and personal protection, and updates from the Laboratory of Medical Zoology are archived at the link above.
Ixodes scapularis adults have been active all winter, as they typically are from October through May, and “quest” or search for hosts at any point when daytime temperatures are above freezing. Deer tick nymphs (immatures) are also active at this time, and may be encountered now through August. For images of all deer tick life stages, along with an outline of the diseases they carry, visit: http://www.tickencounter.org/tick_identification/deer_tick .
Anyone working in the yard and garden on springtime cleanup and planting 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: http://www.tickencounter.org/prevention/protect_yourself .
Have you just removed an attached tick from yourself or a loved one with a pair of tweezers? If so, consider sending the tick to the UMass Laboratory of Medical Zoology to be tested for disease causing pathogens. To submit a tick to be tested, visit: https://www.tickreport.com/ and click on the blue “Order a TickReport” button. Results are typically available within 3 business days, or less. By the time you make an appointment with your physician following the tick attachment, you may have the results back from TickReport to bring to your physician to aid in a conversation about risk.
The UMass Laboratory of Medical Zoology does not give medical advice, nor are the results of their tests diagnostic of human disease. Transmission of a pathogen from the tick to you is dependent upon how long the tick had been feeding, and each pathogen has its own transmission time. TickReport is an excellent measure of exposure risk for the tick (or ticks) that you send in to be tested. Feel free to print out and share your TickReport with your healthcare provider.
- Eastern Spruce Gall Adelgid: Adelges abietis is a pest of Norway spruce primarily, but occasionally damages other spruce species. This adelgid overwinters as a partially grown female, often referred to as a stem mother. This overwintering individual matures around bud break and lays 100-200 eggs. The eastern spruce gall adelgid may be targeted for management between 22-170 GDD’s, base 50°F.
- Eastern Tent Caterpillar: Malacosoma americanum caterpillars can be seen feeding on susceptible hosts and creating their webs (“tents”). See regional reports above for updates. 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. 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.
- Elongate Hemlock Scale: Fiorinia externa is found on eastern, Carolina, and Japanese hemlock, as well as yew, spruce, and fir. Crawlers will be present this month and throughout the growing season and the overlap of many developmental stages at any given time can be observed. 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.
- Emerald Ash Borer: (Agrilus planipennis, EAB) Since the New Year, the Massachusetts Department of Conservation and Recreation has confirmed 26 new community detections of emerald ash borer in Massachusetts. While the cities and towns with recent detections of EAB are too numerous to list here, they are in areas of Berkshire, Hampden, Hampshire, Middlesex, and Worcester counties. A map of these locations and others previously known across the state may be found here: https://ag.umass.edu/fact-sheets/emerald-ash-borer .
This wood-boring beetle readily attacks ash (Fraxinus spp.) including white, green, and black ash, has also been found developing in white fringe tree (Chionanthus virginicus), and has been reported in cultivated olive (Olea europaea). Adult insects of this species will not be present at this time of year. Signs of an EAB infested tree may include (at this time) D-shaped exit holes in the bark (from adult emergence in previous years), “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. Positive identification of an EAB-infested tree may not be possible with these signs individually on their own.
For further information about this insect, please visit: https://ag.umass.edu/fact-sheets/emerald-ash-borer . If you believe you have located EAB-infested ash trees, particularly in an area of Massachusetts not identified on the map provided, please report here: http://massnrc.org/pests/pestreports.htm .
- 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. Still small Euonymus caterpillars continue to feed on European spindle tree foliage in Amherst, MA as observed on 5/14 and again on 5/20/2019. Caterpillars can be seen webbing foliage together, feeding, and packing that webbing full of their tiny, black frass pellets. As these caterpillars grow in size, so do their webs and entire branches may become defoliated or unsightly.
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.
- European Pine Sawfly: Neodiprion sertifer caterpillars are active roughly between 78-220 GDD, base 50°F. The primary host in MA is Mugo pine but it can be found on Scots, red, jack, and Japanese red pine, and also on white, Austrian, ponderosa, shortleaf, and pitch pine when near the aforementioned species. This dark colored caterpillar feeds in tight groups and small numbers can be pruned or plucked out of host plants and destroyed. Larger numbers can be treated with an insecticidal soap spray when the caterpillars are still small. Spinosad products can be used whenever the caterpillars are actively feeding, usually by mid-May and when caterpillars are still small. Bacillus thuringiensis kurstaki is not effective against sawflies.
- Forest Tent Caterpillar: Malacosoma disstria caterpillars were observed feeding on oak leaves in Amherst, MA on 5/14/19 and again on 5/21/19. Individuals of this native insect may be found feeding alongside gypsy moth caterpillars in the same location. Susceptible hosts whose leaves are fed on by this insect include oak, birch, ash, maple, elm, poplar, and basswood.
- 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. Monitor susceptible hosts for small, inch-worm like caterpillars. Where populations are low, no management is necessary.
- Imported Willow Leaf Beetle: Plagiodera versicolora adult beetles overwinter near susceptible hosts. A few adult imported willow leaf beetles were seen feeding on willow foliage in Chesterfield, MA on 5/11/19 and no mating or egg laying was seen at the time. By 5/22/19, it was very easy to spot adult imported willow leaf beetles feeding and mating, as well as the damage they cause to the leaves. Egg laying was also observed on 5/22/19. Adult beetles will chew holes and notches in the leaves of willow. Adult beetles mate and lay eggs through the end of this month. 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.
- Lily Leaf Beetle: Lilioceris lilii overwintering adults have been reported by scouts in the Southeast Region previously. Adults overwintered in sheltered places and are now active with warm temperatures and available food sources. Although adult beetles were not seen during the chilly weather on 5/13/19 in Amherst, MA, previously laid eggs were located on host plant foliage in this location. As of 5/21/19, egg hatch had occurred and larvae of various sizes could be seen feeding on foliage in groups. Smaller larvae skeletonize leaves, whereas larger larvae can eat the entire leaf. 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.
- Snowball Aphid: Neoceruraphis viburnicola 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.
- Spotted Lanternfly: (Lycorma delicatula, SLF) is not known to occur in Massachusetts landscapes (no established populations are known in MA at this time). However, officials with the Massachusetts Department of Agricultural Resources (MDAR) recently urged residents to check plants for spotted lanternfly. On February 21, 2019 MDAR announced the discovery of a single dead spotted lanternfly adult at a private residence in Boston. As a result of this discovery, officials asked the public to check potted plants they purchase and report any suspicious insects. MDAR reports that this particular individual appeared to have been unintentionally transported this past December in a shipment of poinsettia plants originating from Pennsylvania. Officials also report that there is currently no evidence that this pest has become established in MA. For more information about this finding, please visit the MA Department of Agricultural Resources press release:https://www.mass.gov/news/state-agricultural-officials-urge-residents-to-check-plants-for-spotted-lanternfly .
This insect is a member of the Order Hemiptera (true bugs, cicadas, hoppers, aphids, and others) and the Family Fulgoridae, also known as planthoppers. The spotted lanternfly is a non-native species first detected in the United States in Berks County, Pennsylvania and confirmed on September 22, 2014.
The spotted lanternfly is considered native to China, India, and Vietnam. It has been introduced as a non-native insect to South Korea and Japan, prior to its detection in the United States. In South Korea, it is considered invasive and a pest of grapes and peaches. The spotted lanternfly has been reported from over 70 species of plants, including the following: tree of heaven (Ailanthus altissima) (preferred host), apple (Malus spp.), plum, cherry, peach, apricot (Prunus spp.), grape (Vitis spp.), pine (Pinus spp.), pignut hickory (Carya glabra), Sassafras (Sassafras albidum), serviceberry (Amelanchier spp.), slippery elm (Ulmus rubra), tulip poplar (Liriodendron tulipifera), white ash (Fraxinus americana), willow (Salix spp.), American beech (Fagus grandifolia), American linden (Tilia americana), American sycamore (Platanus occidentalis), big-toothed aspen (Populus grandidentata), black birch (Betula lenta), black cherry (Prunus serotina), black gum (Nyssa sylvatica), black walnut (Juglans nigra), dogwood (Cornus spp.), Japanese snowbell (Styrax japonicus), maple (Acer spp.), oak (Quercus spp.), and paper birch (Betula papyrifera).
The adults and immatures of this species damage host plants by feeding on sap from stems, leaves, and the trunks of trees. In the springtime in Pennsylvania (late April - mid-May) nymphs (immatures) are found on smaller plants and vines and new growth of trees and shrubs. Third and fourth instar nymphs migrate to the tree of heaven and are observed feeding on trunks and branches. Trees may be found with sap weeping from the wounds caused by the insect’s feeding. The sugary secretions (excrement) created by this insect may coat the host plant, later leading to the growth of sooty mold. Insects such as wasps, hornets, bees, and ants may also be attracted to the sugary waste created by the lanternflies, or sap weeping from open wounds in the host plant. Host plants have been described as giving off a fermented odor when this insect is present.
Adults are present by the middle of July in Pennsylvania and begin laying eggs by late September and continue laying eggs through late November and even early December in that state. Adults may be found on the trunks of trees such as the tree of heaven or other host plants growing in close proximity to them. Egg masses of this insect are gray in color and, in some ways, look similar to gypsy moth egg masses.
Host plants, bricks, stone, lawn furniture, recreational vehicles, and other smooth surfaces can be inspected for egg masses. Egg masses laid on outdoor residential items such as those listed above may pose the greatest threat for spreading this insect via human aided movement.
For more information about the spotted lanternfly, visit this fact sheet: https://ag.umass.edu/landscape/fact-sheets/spotted-lanternfly
- 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. When damaging spruce spider mite populations are known from last season, dormant oil applications can be made (when temperatures are appropriate according to label instructions) between 7-121 GDD’s, base 50°F. 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.
- Viburnum Leaf Beetle: Pyrrhalta viburni is a beetle in the family Chrysomelidae that is native to Europe, but was found in Massachusetts in 2004. See Regional Reports above for updates regarding the activity of this pest. 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. Larvae, when they are present, may be treated with a product containing spinosad once they appear. 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 will be pupating this month and 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. Woolly apple aphid was observed on elm on 5/13/2019 in Amherst, MA. 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.
- 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. Curled leaves, due to the activity of the woolly elm aphid, were observed in Amherst, MA on 5/13/19. 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.
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 .
A note about Tick Awareness: deer ticks (Ixodes scapularis), the American dog tick (Dermacentor variabilis), and the lone star tick (Amblyomma americanum) are all found throughout Massachusetts. Each can carry their own complement of diseases. Anyone working in tick habitats (wood-line areas, forested areas, and landscaped areas with ground cover) should check themselves regularly for ticks while practicing preventative measures. Have a tick and need it tested? Visit the web page of the UMass Laboratory of Medical Zoology https://www.tickreport.com/ and click on the blue Order a TickReport button for more information.
Reported by Tawny Simisky, Extension Entomologist, UMass Extension Landscape, Nursery, & Urban Forestry Program