New Haven Register (Sunday) (New Haven, CT)
The moth that endangers state’s trees has a new name
Gypsy moths are now spongy moths. No matter the name, their newly hatched caterpillars are hard-wired to be hungry.
So there’s a good chance Litchfield County hardwoods will be hurting, unless the spring is rainy.
“Unfortunately, there’s a lot of egg mass out there,” said Chris Martin, state forester with the state Department of Energy and Environmental Protection.
“Right now, we’re expecting a huge hatch,” said Jeff Perotti, Sharon’s tree warden.
First, the name change. In March, the American Entomological Society officially changed the moths’ name. Finding “gypsy moth’’ an insult to the Romani people, the society changed the moth’s common name to spongy, after the spongy egg mass the females lay before dying.
The Latin name — Lymantria dispar — stays the same
Whatever the name, generations have dreaded an outbreak of the moths’ caterpillars, which hatch by the hundreds of thousands in May and June, defoliating trees by feeding on their leaves. Anyone old enough to remember spongy moth outbreaks in the state in the 1970s and 1980s can attest to seeing the woods bare, their beloved oaks and maples chewed to the nub.
After years of quiescence, there was a dramatic spongy moth infestation in several towns in Litchfield County in 2021, centered around Cornwall and Sharon. Martin said it affected about 40,000 acres of forests.
Josh Tanner, Warren’s tree warden, witnessed this for the first time last year.
“I’m only 35, so I never saw the outbreaks in the 1980s,’’ he said. “It was something to see the trees so leafless.”
Spongy moths are a nonnative, invasive species.
Leopold Trouvelot, an amateur lepidopterist, imported the moths - native to Europe, Asia and Africa — to his home in Medford, Mass. in 1866, hoping to start an American silk industry. The moths escaped and instead, started a North American environmental disaster.
The female spongy moth lays its egg mass on any hard surface in the summer. The eggs overwinter and the caterpillars — hairy, hungry — hatch in the spring. They crawl to the tops of trees, hanging by a single silky thread. If the wind blows, the caterpillars sail off, land and start eating again.
After about six weeks of feeding, they pupate, and emerge in the summer as moths. The moths mate and die soon after.
What’s held the moths in check is a fungus — Entomophaga maimaiga. It was released in the Boston area to combat the moths in the early 1900s and suddenly blossomed out to do its job in the 1980s.
The fungus releases spores. These spores attach themselves to a spongy moth caterpillar and inject it with a killing enzyme. The spores then multiply inside the dead caterpillar by the hundreds of thousands. Released, they go forth to kill more.
But for the fungus to function, it needs a releasing rain especially in May and early June. That didn’t happen in 2021 in Litchfield County.
In the drought years of 2015-2017, repeated spongy moth outbreaks affected more than a million acres of woods in eastern Connecticut. Because there was so little rain, the fungus never hatched until 2018. The outbreaks killed thousands of acres of forest.
“By the end, the caterpillars were eating mountain laurel leaves, hemlock needles — anything green,” the DEEP’s Martin said
Martin said most trees recover from a single year of spongy moth damage by growing new leaves.
“But it puts an enormous amount of stress on the trees,” he said. Repeated infestations can kill them.
Kirby Stafford, state entomologist at the Connecticut Agricultural Experiment Station, said he hopes the rain that’s fallen this month will help activate the fungus.
He said he’s also seen evidence tiny parasitic wasps have attacked and damaged some of the moth egg masses in Litchfield County.
But a female spongy moth lays thousands of eggs in a single mass and there were countless spongy moths in Litchfield County in 2021. So Stafford said even under the best of conditions, there will probably be some damage to the county’s trees this year.
What’s clear is that spongy moths aren’t going away. The fungus, the wasps, may kill most of the caterpillars off. But a few moths survive, lay eggs and slowly build up numbers. Then, if the conditions are right, a caterpillar army crawls forth to feed.
“It seems to run roughly in a 10-year cycle,” Stafford said. “They seem to be gone, then they show up. It is amazing.”