Growing gypsy moth population cause of worry for campus

A gypsy moth infestation is especially dangerous to UConn because the larvae of these harmful insects are harmful to New England’s foliage. (Amar Batra/The Daily Campus)

UConn, along with the whole of New England, has been faced with the challenge of controlling the gypsy moth population from destroying the leaves of many species of trees for the past several decades, according to Dr. Ana Legrand, an entomology extension professor at UConn.

According to the U.S. Department of Agriculture Forest Services, the larvae of these harmful insects are harmful to New England’s foliage. The larvae will eat the leaves of their host trees until the trees become defoliated.

Legrand said, “This is one of the worst summers (for gypsy moth infestations) for the UConn area. Trees were hard hit this summer, some were extremely defoliated.”

This poses a danger to UConn’s trees because according to UConn College of Agriculture, Health and Natural Resources plant data base, the Storrs campus is home to 15 different species of oak, as well as many other hardwood trees.

The problem began when the moths were brought to the United States in 1869 by Étienne Léopold Trouvelot, who hoped to use them to improve the silk industry. They escaped his lab in Massachusetts and quickly spread throughout New England.

These moths cause a widespread loss of leaves, a process cause defoliation, through early spring into late summer, according to Forest Services.

“It’s a problem because (gypsy moths), being a nonnative insect, have no natural controls in the area,” Legrand said.

In a hope to fight the spread of these insects a fungus called Entomophaga Maimaiga was introduced in 1910. It failed to work and lay dormant until the 1980’s, when it was discovered that the fungus affects the exoskeletons of the young gypsy moth larvae, killing them within a week, according to data from The Connecticut Agricultural Experiment Station.

Forest Services said that defoliation is especially bad when the moths are in high density, which happens every few years in cycles. During this period of high density more than 50 percent of a tree's leaves can be affected.

Connecticut has had increasingly larger infestations of these insects over the past few years because of the extremely dry springs and summers, which causes issues with the growth of the fungus, Legrand said.

“The fungus needs moisture to help control the moths and without rain in the spring, the moths thrive,” Legrand said.

If ecological conditions are right, hopefully the fungus will thrive next year, helping keep gypsy moths under control
— Dr. Ana Legrand, Entomology Professor

This past year there was more rain than in the recent past, but because it came so late, some moths were able to develop before they were killed by the fungus and were able to lay eggs for next year, according to Legrand.

To help control the population of moths for the upcoming year, Legrand recommends that students keep an eye for the egg masses the gypsy moths leave on trunks of trees.

She said that if spotted, “they should be destroyed completely after scraping them off by throwing them away... Because they are resilient, if they’re left at the trunk of the trees they will survive.”

Forest Services states that the trees with the highest risk are oaks, because of the moths’ preference for hardwood. Other trees at risk include hemlock, pines and spruces. If these trees were affected by these moths, these trees may be at risk of losing radial growth, depending on what percentage of the tree’s crown is affected.

If there has been very little defoliation of the tree in the past, it is more likely to refoliate quickly, according to Forest Services.

In terms of future gypsy moth populations, Legrand is hopeful.

“If ecological conditions are right, hopefully the fungus will thrive next year, helping keep gypsy moths under control,” Legrand said


Molly Desrochers is a campus correspondent for The Daily Campus. She can be reached via email at molly.desrochers@uconn.edu.