Photo-worthy insects and insect feeding, because not all insects we see in our landscapes are pests:
- Leafcutter Bee Evidence: Evidence of leafcutter bee activity was observed on 9/20/17 in Amherst, MA on eastern redbud (Cercis canadensis). Some of the most common leafcutter bees belong to the genus Megachile. These bees look similar to bumble bees, except they may be smaller with rows of white hair on the abdomen. These species of bee are solitary, meaning that each female tends her own nest (does not live in a social hive arrangement). The bees cut disks from certain plant leaves, which they then use to line and plug up cells used for their eggs. Each bee can make multiple cells for this purpose in hollow stems, twigs, and other protected areas. These bees are native to the United States and can be important pollinators. Although they may cut circular disks from the leaves of roses, azaleas, ash, redbud, and other ornamental plants, the damage they cause is negligible and does not impact overall plant health.
- Orange Dog/Giant Swallowtail: The caterpillar stage ofPapilio cresphontes is certainly photo-worthy. This insect is widely distributed throughout the United States and much of North, Central, and South America. Host plants include members of the Rutaceae, the citrus family, including but not limited to prickly ash (Zanthoxylum spp.), torchwood (Amyris spp.), and hoptree/wafer ash (Ptelea trifoliata). The two caterpillars pictured here were collected from wafer ash on 9/21/17 in Amherst, MA. These caterpillars may partially defoliate small, potted plants but are otherwise not problematic. They may be considered minor pests in certain Citrus spp. crops. The adult butterflies of this species will sip nectar from flowering plants such as azalea, Japanese honeysuckle, goldenrod, and swamp milkweed but can be common to many flowering plants. The adult butterfly is quite the attractive swallowtail, however these caterpillars can be appreciated as well. The orange dog caterpillars (or orange puppy depending on who you ask) possess iridescent sapphire-blue spots and defense-related patterns: bird dropping-like markings coupled with what some call snake-mimicry. Scale-like markings, like those of a snake, can be seen on more mature caterpillars, near the thorax. But perhaps the most impressive defense mechanism of all is the bright red osmeterium that the caterpillar will exude when irritated. This structure may look like the forked tongue of a snake, but it is a gland that contains a mixture of chemicals that produce a putrid smell. This pungent aroma has been described by some as similar to that of “rancid butter”. The aroma is certainly unpleasant and surprisingly strong.
Woody ornamental insect and non-insect arthropod pests to consider, a selected few:
- 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, or have captured an adult beetle that you believe to be ALB, 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.
- Elongate Hemlock Scale: Fiorinia externa is found on eastern, Carolina, and Japanese hemlock, as well as yew, spruce, and fir. Crawlers will be present throughout the growing season and the overlap of many developmental stages at any given time can be observed.
- Emerald Ash Borer (EAB): A new county detection of Agrilus planipennis (EAB) was made using green panel traps and a combination of a host plant volatile chemical and pheromone (sexual attractant) lures placed in Brookline, MA. This is unfortunately a new county detection (Norfolk County) in Massachusetts for 2017. (However, it is in very close proximity to a prior detection made in Suffolk County.) EAB has previously been detected in Berkshire County (2012), Essex County (2013), Suffolk County (2014), Worcester County (2015), and Hampden County (2016). In this case, two green panel traps, hung in close proximity to one another, captured 6 adult beetles between them, which were collected on 7/14/17 and sent to the UMass Plant Diagnostic Laboratory for confirmation. This identification was also confirmed by the USDA Animal and Plant Health Inspection Service (APHIS).
EAB readily attacks ash (Fraxinus spp.) including white, green, and black ash and has also been found developing in white fringe tree (Chionanthus virginicus) and most recently, cultivated olive (Olea europaea). (See: https://academic.oup.com/jee/article-lookup/doi/10.1093/jee/tox139) Signs of an EAB infested tree may include D-shaped exit holes in the bark, “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/upon peeling 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 a map of the known locations of emerald ash borer in the state, as well as 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 it at the Massachusetts Introduced Pests Outreach Project: http://massnrc.org/pests/pestreports.htm.
- Fall Home-Invading Insects: Various insects, such as ladybugs, boxelder bugs, seed bugs, and stink bugs have begun to seek overwintering shelters in warm places, such as homes. While such invaders do not cause any measurable structural damage, they can become a nuisance especially when they are present in large numbers. If you are not willing to share your home with such insects, now should be the time to repair torn window screens, repair gaps around windows and doors, and sure up any other gaps through which they might enter the home.
- Fall Webworm: Hyphantria cunea is native to North America and Mexico. It is now considered a world-wide pest, as it has spread throughout much of Europe and Asia. (For example, it was introduced accidentally into Hungary from North America in the 1940’s.) Hosts include nearly all shade, fruit, and ornamental trees except conifers. In the USA, at least 88 species of trees are hosts for these insects, while in Europe at least 230 species are impacted. In the past history of this pest, it was once thought that the fall webworm was actually two species. It is now thought that H. cunea has two color morphs – one black headed and one red headed. These two color forms differ not only in the coloration of the caterpillars and the adults, but also in their behaviors. Caterpillars may go through at least 11 molts, each stage occurring within a silken web they produce over the host. When alarmed, all caterpillars in the group will move in unison in jerking motions that may be a mechanism for self-defense. Depending upon the location and climate, 1-4 generations of fall webworm can occur per year. Fall webworm adult moths lay eggs on the underside of the leaves of host plants in the spring. These eggs hatch in late June or July depending on climate. Young larvae feed together in groups on the undersides of leaves, first skeletonizing the leaf and then enveloping other leaves and eventually entire branches within their webs. Webs are typically found on the terminal ends of branches. All caterpillar activity occurs within this tent, which becomes filled with leaf fragments, cast skins, and frass. Fully grown larvae then wander from the webs and pupate in protected areas such as the leaf litter where they will remain for the winter. Adult fall webworm moths emerge the following spring/early summer to start the cycle over again. 50+ species of parasites and 36+ species of predators are known to attack fall webworm in North America. Fall webworms typically do not cause extensive damage to their hosts. Nests may be an aesthetic issue for some. If in reach, small fall webworm webs may be pruned out of trees and shrubs and destroyed. Do not set fire to H. cunea webs when they are still attached to the host plant.
- Hickory Tussock Moth: Lophocampa caryae is native to southern Canada and the northeastern United States. There is one generation per year. Overwintering occurs as a pupa inside a fuzzy, oval shaped cocoon. Adult moths emerge approximately in May and their presence can continue into July. Females will lay clusters of 100+ eggs together on the underside of leaves. Females of this species can fly, however they have been called weak fliers due to their large size. When first hatched from their eggs, the young caterpillars will feed gregariously in a group, eventually dispersing and heading out on their own to forage. Caterpillar maturity can take up to three months and color changes occur during this time. These caterpillars are essentially white with some black markings and a black head capsule. They are very hairy, and should not be handled with bare hands as many can experience skin irritations or rashes (dermitis) as a result of interacting with hickory tussock moth hairs. By late September, the caterpillars will create their oval, fuzzy cocoons hidden in the leaf litter where they will again overwinter. Hosts whose leaves are fed upon by these caterpillars include but are not limited to hickory, walnut, butternut, linden, apple, basswood, birch, elm, black locust, and aspen. Maple and oak have also been reportedly fed upon by this insect. Several wasp species are parasitoids of hickory tussock moth caterpillars.
- Lace Bugs: 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 bugs should be monitored through September. Fall or early spring soil treatment with imidacloprid has been effective, but be aware of the implications this may have on pollinators attracted to these flowering plants when making management decisions. Certain azalea and andromeda cultivars may be less preferred by lace bugs.
- Tuliptree Scale: Toumeyella liriodendri is a species of soft scale insect (Family: Coccidae) that is native to the United States and found in much of the eastern US, but also has been recorded in California. It appears to be present wherever host trees are found. It is another one of the larger scale insects found in the United States, a close second in size to the magnolia scale. Adult female tuliptree scales can measure up to ¼ to just under ½ inch in length. Host plants include Liriodendron tulipifera (tuliptree or yellow poplar), Magnolia stellata (star magnolia), and M. soulangeana (Chinese magnolia). This insect has also been recorded on M. grandiflora (southern magnolia), Tilia spp. (linden), and to a lesser extent, on other ornamental trees and shrubs. When this insect is present on magnolias, such as those mentioned above, it is often confused for the magnolia scale (Neolecanium cornuparvum). The two may be similar in size and have similar life cycles. The mature female tuliptree scale is hemispherical in shape. Color of the mature female varies in this species as well, a grayish-green to pink-orange insect mottled with black. Adult males emerge sometime in June and mate with the females. Eggs develop within the body of the female tuliptree scale, leading to the “live birth” of immatures (crawlers) in late August and September. In the Northeast, one generation of tuliptree scales occurs per year. (However, in the southern-most portions of its range, this insect has been found in all stages of development during the winter, suggesting multiple generations per year.) A single female tuliptree scale may produce 3,000+ crawlers in one season. These crawlers are tiny (approximately the size of the head of a pin) and settle on host plant twigs in September. Past studies have shown that in addition to moving on their own with fully functional legs, the crawlers can be blown to new hosts on the wind, up to 100 feet away. (Being wind-blown to a new host, however, is a haphazard method of travel through which some less than 20% of these crawlers successfully make contact with a host plant, and fewer still attach to a suitable site on the plant.) The immature, crawler stage molts once prior to overwintering. The natural enemies of the tuliptree scale include certain lady beetle species (Hyperaspis signata, Adalia (formerly Hyperaspis) bipunctata, and Chilocorus stigma) which feed on nymphal scales, a number of parasitic wasps, and even an insect-feeding moth caterpillar (Laetilia coccidivora). This particular moth species, also referred to as a type of snout moth, will consume the tuliptree scale underneath the protection of a silken web it spins over them. (The specific epithet coccidivora can be translated as “ones that eat soft scales” or Coccidae.) Unfortunately, in a landscape setting, it often seems that although these natural enemies may be common within the scale populations, they are seldom able to reduce the scale insect numbers below damaging levels. That being said, our management options should seek to preserve these natural enemies.
Management options for the tuliptree scale (Touymeyella liriodendri) include mechanical management by removing scales by hand or pruning and destroying infested plant material when practical/possible. High-pressure water sprays can at times dislodge scale insects from smaller host plants, yet care must be taken to avoid plant damage. Although this is a soft scale, foliar applications of insecticides should still target the crawler or immature stages of this insect, as the tuliptree scale is covered with a protective waxy layer for most of its life cycle. Many active ingredients are also available for use against the tuliptree scale, but reduced risk products may include horticultural oil, insecticidal soap, and neem oil. Dormant oils may be applied between 12-121 Growing Degree Days, Base 50°F, for this pest. Foliar insecticides may be applied between 2032-2629 Growing Degree Days, Base 50° F, or roughly in late August through mid-September.
- Viburnum Leaf Beetle: Pyrrhalta viburni is a beetle in the family Chrysomelidae that is native to Europe, but was found in Massachusetts in 2004. Adult beetles are expected to be active roughly through October, or when the first frost hits. Adult beetles will create their own feeding damage, but will also mate and females will lay eggs in the stems of the viburnums, typically beginning in late-June to mid-July until October. This beetle feeds exclusively on many different species of viburnum including but 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/.
- Chilli Thrips: The non-native, exotic chilli thrips (Scirtothrips dorsalis) has been confirmed from two samples of damaged Hydrangea spp. foliage from two residential landscapes located in Barnstable County, MA submitted to the UMass Plant Diagnostics Laboratory. At this time, this pest has not been confirmed in nurseries or greenhouses in Massachusetts or on any other host plants. Due to the limited number of samples, the significance of chilli thrips in Massachusetts is not yet known. This species of thrips is a significant global pest of economically important ornamental, vegetable, and fruit crops in southern and eastern Asia, Oceania, and parts of Africa. It was first determined to be established in the United States in 2005 in Florida, although previous interceptions of this pest were detected. It is reportedly a pest of over 100 host plants belonging to over 40 plant families, including, but not limited to, pepper, strawberry, blueberry, cotton, rose, peanut, Japanese privet, Rhododendron spp., Viburnum spp., eggplant, grapes, melon, tobacco, and tomato. For more information, please visit this Chilli Thrips Fact Sheet: https://ag.umass.edu/landscape/fact-sheets/chilli-thrips
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.
Pollinator Protection Resource Online: The Massachusetts Department of Agricultural Resources has developed a Massachusetts Pollinator Protection Plan. It is a set of voluntary guidelines that discuss best management practices for stakeholders seeking to promote the health of the European honeybee and other pollinators. This document includes information for beekeepers, pesticide applicators, land managers and farmers, nurseries and landscapers, and homeowners and gardeners. Please locate the MA Pollinator Protection Plan for more information here: http://www.mass.gov/eea/docs/agr/farmproducts/apiary/pollinator-plan.pdf.
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 red Test a Tick button for more information.
Report by Tawny Simisky, Extension Entomologist, UMass Extension Landscape, Nursery, & Urban Forestry Program