Winter Moth Caterpillars Defoliating Trees Across State

May 21, 2014

The Department of Environmental Management is tracking areas where winter moth infestations are most prevalent in the state. The agency is asking Rhode Islanders to report areas where winter moth caterpillars are heavily defoliating trees.

Defoliated leaf and winter moth caterpillar.
Credit Courtesy of the Rhode Island Department of Environmental Management

“We want to tell people that if their trees are defoliated, it would be a good idea to water them if they start to re-foliate, because the tree will need a lot of water to get the leaves back out again,” said Bruce Payton, state forester and the DEM’s deputy chief of the division of forest environment.

Payton said water is enough for the trees – it’s too late in the season for fertilizer. He said an astonishing number of caterpillars are defoliating ash, elm, oak, beech, basswood, and fruit trees in Providence, Warwick, South Kingstown, North Kingstown, East Greenwich, and Cumberland.

The winter moth caterpillars, also called “loopers” or “inchworms,” are pale green with white long stripes running along both sides of the body. 

The caterpillars’ natural predator, a parasitic fly, has to be released early in the game, said Payton.

“The release happened last year already for this year, and what we're doing now is looking for locations for release for next May,” said Payton.

Payton said the caterpillars end up eating fly eggs laid on leaves that caterpillars munch on. The eggs hatch as larval flies inside the caterpillar, killing them and emerging as adults to attack more caterpillars the next spring.  Researchers say the fly has successfully destroyed the winter moths in Europe without hurting any other organisms.

Report Infestations

Email Bruce Payton at Include your name, phone number, and the location you're reporting with infestation.