A version of this article first appeared in UConn Today, June 13, 2019.
Connecticut residents are all too familiar with the damage wrought by gypsy moths. In their larval stage as caterpillars, their voracious appetites can defoliate trees, particularly oaks. While healthy trees usually recuperate and grow new leaves, the extent of the defoliation along with drought conditions over the past few years have impeded their recovery. Dry spring weather can also prevent growth of the fungus Entomophaga maimaiga, which suppresses the gypsy moth population, exacerbating the effects this troublesome pest has recently brought to parts of the state.
Windham County has been among the most severely affected areas in the state over the last few years. Canterbury First Selectman Christopher Lippke says gypsy moths are responsible for nearly 600 dead trees along the town’s roads. Falling trees and limbs can injure people and damage property, hinder commuters and emergency responders and bring down power lines. Dead wood also increases the risk of wildfires. As they deal with hazardous trees and take measures to prevent future gypsy moth damage, Lippke and many others have engaged the resources of UConn Extension.
UConn Extension provides outreach education to help individuals, communities and businesses solve problems in the areas of food, health and sustainability.
Throughout Connecticut’s Quiet Corner, Associate Extension Professor Tom Worthley has met with citizens and community leaders about what they can do to combat gypsy moths and safely manage their forests and roadsides. Worthley has a joint appointment in the Department of Natural Resources and the Environment (NRE), where he teaches forest sustainability and serves as steward of the UConn Forest. As an extension forester, he works throughout the state, providing outreach education on forest ecology and tree management. Recently, he has spent much of his time addressing tree mortality.
“During the spring and summer of 2018, the impact of previous years’ drought, defoliation and secondary opportunistic pathogens became apparent as tens of thousands of roadside trees throughout eastern Connecticut and thousands of acres of oak woodlands exhibited severe mortality,” says Worthley. “Since then, we’ve convened several meetings of stakeholders concerned about dead roadside trees as potential safety hazards, including representatives from the public utilities, Department of Transportation, Department of Energy and Environmental Protection, professional arborists, tree wardens and others. We conveyed the extent and seriousness of the problem and fostered some communication and cooperation.”
“The extent of the damage became very apparent last year as we were looking at the trees,” says Lippke. “We thought they were blooming late and then when they weren’t blooming by June, we knew we had a serious problem. Tom got the ball rolling for us.”
Students from NRE worked with Worthley to assess the extent of the damage in Canterbury, noting that there were stretches of roadways with thirty to forty dead trees per mile. Towns are facing prohibitive costs: the cost of cutting down a single tree can be hundreds of dollars. Worthley has formed a working group of town and state officials, representatives from utility companies and members of the forestry and arboricultural communities to assist municipal leaders with managing affected areas.
“It’s great working with UConn and we appreciate the work Tom has done,” says Lippke. “His expertise and knowledge are helping us be proactive rather than reactive.”
Worthley has spoken with a number of professional groups and local organizations about gypsy moths, discussing management options available to homeowners and landowners and advising on how to control the gypsy moth population before outbreaks and what they can do in the midst of one. Last year, Worthley stopped by the Danielson Veterans Coffeehouse and spoke at the Woodstock Town Hall in an event co-sponsored by the Woodstock Conversation Commission and the New Roxbury Land Trust.
The Danielson Veterans Coffeehouse is a group of former members of the armed services that welcome guest speakers on a variety of topics. Tom Pandolfi, one of the coffeehouse’s organizers, invited Worthley. While presentations are often only for veterans, Worthley’s talk was open to all.
Says Pandolfi, “We had the event open to the public because it’s important to everybody of interest not just to veterans, but every homeowner.”
Worthley explains there are steps that can be taken to eradicate gypsy moths and mitigate damage to trees.
The E. maimaiga fungus is one of the most effective natural controls for gypsy moths, killing caterpillars on contact. However, its emergence is highly dependent on spring rains.
One of the easiest and most cost-effective solutions to stave off gypsy moths can be implemented beginning in mid-summer when female moths lay clusters of eggs of, a few hundred to a thousand eggs. The eggs hatch the following spring in late April and early May. The new caterpillars feed on trees and shrubs for the next forty days or so. They prefer oak and beech trees, but will feed on the leaves of 500 different species of trees and shrubs. A single caterpillar can consume as much as eleven square feet of leaves.
Egg masses can be destroyed by removing them and soaking them with soap or oils, such as canola or soybean, and water. Moths lay eggs anywhere protected from the elements, commonly under tree bark or branches, fences and decks. Unfortunately, egg masses can be high in trees and winds can blow them around, so even the most thorough attempts will not completely eradicate them. Chemical and biological insecticides options are available; Worthley suggests contacting an arborist or Certified Forester for information.
If eggs have already hatched and caterpillars are present, as they are at this time of year, banding trees with a burlap barrier or tape can stop and trap caterpillars. Caterpillars climb up trees to feed at night and descend during the day to seek protection from predators like deer mice, shrews and insects. Minerals or soybean sprays can be used to suffocate caterpillars.
For trees that have no buds or leaves, Worthley says now is the time to contact an arborist or qualified tree service. Woodland owners should consult with a Certified Forester to examine the affected area.
“State forest lands and many private parcels in eastern Connecticut have been affected by oak mortality,” says Worthley. “Canopy loss is quite severe on tens of thousands of acres, and there is partial canopy loss on many more from the Rhode Island line to west of the Connecticut River.”
Worthley has met with legislators about gypsy moth damage and tree mortality across the state. In May 2019, Worthley and other forestry experts guided Congressman Joe Courtney through Pachaug Forest to survey tree damage. Courtney has discussed the possibility of using federal funds to address gypsy moth outbreaks, recognizing the cost of clearing dead and dying trees.
“The scale and scope of tree mortality in eastern and central Connecticut is a potential public safety hazard and a problem beyond the capacity of towns, the Department of Transportation and utilities,” says Worthley. “Dead trees are more dangerous the longer they are left to stand. Time is of the essence.”