In a press release from the Department of Energy and Environmental Protection late last month, the Connecticut Agricultural Experiment Station announced that there was gypsy moth -- Lymantria dispar -- activity across the state, coupled with some pockets of tree defoliation. However, the increased moth activity does not necessarily indicate that long term issues are ahead, according to the CAES.
The gypsy moth is one of the most devastating forest pests in North America, says the the U.S. Forest Service. In its larval stage (when it’s a caterpillar), the moth chews through leaves on host trees. Normally, a fungus (Entomaphaga maimaigi) controls gypsy moth populations by infecting the larvae. This year saw an abnormally dry spring, which hindered the growth of the fungus.
“The dry spring was mainly responsible for the fungus not kicking in, so the larvae had a chance to grow, and they can cause some damage,” said Dr. Victoria Smith, associate agricultural scientist with the Department of Entomology.
Dr. Victoria Smith
Smith said that she is not too concerned about potential for a long term outbreak.
“We know that once the fungus kicks in, a lot of the larvae are going to die,” she said. The regrowth of the fungus following recent rains will hopefully prevent a larger outbreak next year.
While trees will face defoliation with increased gypsy moth presence this year, Smith said that one bad season will not have dramatic impacts on forest health.
“A healthy tree can withstand a year or maybe two or or maybe three of defoliation, and they’ll be fine,” she said. “It’s going to put stress on the tree, but it’s probably not going to kill your tree.”
The last major gypsy moth outbreak was in the early 1980s, when the moth larvae ate through 1.5 million acres in Connecticut.