“Gypsy moths are having an enormous, explosive year,” said Brian Cassie, founder of the Massachusetts Butterfly Club, to the Sun Chronicle.
On the ground, the bugs are causing agricultural damage and are threatening to pose a significant ecological problem. Some environmentalists fear that if the caterpillars too severely harm oak trees, the wild turkeys, bears and other animals that rely on oak acorns will in turn be affected. Firefighters worry that trees, stripped of their greenery, will be more susceptible to combustion. One Boston Globe reporter took to coating his trees with Vaseline in a futile attempt to keep the animals from climbing into the canopy.
Houses have turned black under the deluge of caterpillar poo. David Hanson, a Massachusetts farmer, told the Associated Press on Sunday that the little bits of chewed-up plant matter are raining down so thick homeowners need brooms to scrape it up.
“Some people are telling me they’re raking their lawn because there’s so much leaf litter on them from the gypsy moth damage,” he said.
This is may be the worst infestation of gypsy moths, according to the Associated Press, since the 1980s.
To trace the source of the infestation requires going back not three decades but a century. Étienne Léopold Trouvelot, a French astronomer living near Boston who was a better artist than he was an entomologist, wanted to see if he could find an animal superior to the silkworm for textile production. His experiment with gypsy moths, imported from Europe, was doubly a failure: The moths did not produce better fibers, and on a blustery day in 1868 or 1869, a gust of wind blew some of Trouvelot’s bugs free from a windowsill.
The insects took to the Medford, Mass., countryside with gusto. There, the caterpillars grew rapidly in number; there were no familiar carnivores to keep the animals in check, and the insects sport irritating spines that deter most North American insect-eaters. (There are a few native birds that are capable of munching on the gypsy moth larvae: Specifically, as Massachusetts NPR station WCAI noted Wednesday, the yellow- and black-billed cuckoos are capable of collecting the spines in their stomach linings and then expelling the hairs as concentrated pellets.)
Each year, in late spring and summer, the caterpillar populations swell. What may be effective in culling the animals, as The Washington Post’s Angela Fritz wrote in June, is the fungus Entomophaga maimaga. The spores, native to Japan, infect the gypsy moth larvae, often fatally so — Cornell University’s mushroom blog describes it as the “caterpillar killer” for its efficiency at consuming the critters from within.
During unseasonably dry springs, however — as May 2014 and 2015 were in New England — the fungus cannot take root, and the cycle continues. The dry spell continued this year, too, threatening a bleak outlook for the next crop of trees.
“Connecticut is potentially facing a huge gypsy moth infestation next summer,” Connecticut Agricultural Experiment Station state entomologist Kirby Stafford told the Hartford Courant.
By now, most of the caterpillars have metamorphosed into moths. But that does not mean they have ceased to inconvenience New Englanders.
A Boston-area radio producer wrote on Twitter that the moths were so numerous at Logan International Airport, his Tuesday flight was delayed for 20 minutes while the pilots waited for the insects to clear.