Cold and Insect Survival
As we dig out snow buried vehicles and yards, insect management may be the last thing on our minds. They’re all frozen or dead, right? While it is not the appropriate time of year for management, these cold temperatures may have us wondering how insect populations are present year to year. Insects are survivors – depending upon the species, they may overwinter (live) in sheltered areas as adults, as eggs on host plants or other surfaces, and still others survive this harsh New England season as partially developed immature stages somewhere in, on, or near host plant parts. There are many strategies insects employ to survive the winter to allow for the continuation of their species in the New Year. While abiotic conditions over the winter can impact insect pest survival, we know that some pest populations are incredibly talented at rebounding. A typical example of this has been the hemlock woolly adelgid (Adelges tsugae) population in Massachusetts. Land managers protecting trees from this insect have noticed significant (over 95% in some cases) winter mortality of these insects in recent years. However, the adelgid’s ability to produce two generations per year, approximately 300 eggs per adult female, and to reproduce in the absence of males allows this insect to recover its population very quickly (all surviving HWA adults in the United States are female; we lack a spruce host found in their native Asia that is needed for sexual reproduction).
Additionally, when thinking about HWA, their ability to survive cold winter temperatures is complex and fascinating. Dr. Joseph Elkinton of UMass Amherst, students, and colleagues determined that hemlock woolly adelgid cold hardiness can vary greatly from year-to-year, week-to-week in Massachusetts, and they found genetic differences in populations ranging from the northern to the southern portions of their range in the eastern United States. Essentially, the cold temperatures required to kill hemlock woolly adelgids will vary year to year and week to week depending upon their exposure to prior temperatures. Their research indicated that adelgid mortality was more highly correlated with variation in temperature, than with an absolute minimum temperature across a range of sites and years (2004-2007) in Massachusetts.
Don’t Forget about Invasive Pests
This also can be a good time of year to keep our eyes open for damage indicative of invasive insects. Damage from the Asian longhorned beetle and the emerald ash borer can at times be easier to spot in the winter in the absence of leaves (as long as trees are not snow-covered). This is still a time of year to be vigilant for pests such as the spotted lanternfly, as we know a single dead individual was detected in a potted poinsettia purchased in Suffolk County in December of last year. It is important to continue to be on the lookout for this and any other potentially invasive pests, and report any suspicious finds: http://massnrc.org/pests/pestreports.htm .
Lastly, the MA Department of Agricultural Resources recently reminded us all to shop locally this holiday season, and purchase Christmas trees and holiday decorations from one of the Commonwealth’s many family-operated farms and nurseries. MDAR cites the many benefits of purchasing local Christmas trees, including a note that Christmas tree farms in MA are often sited on soils that cannot support other crops and that the trees may even stabilize soil, prevent erosion, and offer protection of water supplies. An entomologist might also add that purchasing your Christmas tree or other holiday decorations from local farms and nurseries (not out-of-state sources) may reduce the risk of unintended consequences, such as moving around hitchhiking insect pests that favor coniferous hosts. For more information from MDAR, visit: https://www.mass.gov/news/baker-polito-administration-declares-november-29-2019-as-green-friday .
Wishing everyone a happy, healthy, and peaceful holiday season. The Landscape Message will return in 2020!
Woody ornamental (and other) 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, 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 .
- Emerald Ash Borer: (Agrilus planipennis, EAB) The Massachusetts Department of Conservation and Recreation has recently confirmed EAB in additional communities in Massachusetts. For an updated map of these locations, please visit:https://ag.umass.edu/fact-sheets/emerald-ash-borer .
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. 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 .
- 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) 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 . For a map of the known spotted lanternfly infestations in the United States, as well as locations where this insect has been detected (but not yet established), visit: https://nysipm.cornell.edu/environment/invasive-species-exotic-pests/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 .
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. Remember, just because there is snow, does not mean we can forget about deer ticks. They may become active any time temperatures are above freezing. 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