Gypsy Moth Caterpillars Take R.I. By Surprise

By TIM FAULKNER/ecoRI News staff

The worst hit have been oak and other hardwood trees in rural areas.

The worst hit have been oak and other hardwood trees in rural areas.

Gypsy moths are back, and, according to Rhode Island officials, it’s a full-fledged outbreak not seen since the early 1980s.

“We don’t know where it came from. We were totally taken by surprise by the extent of the infestation,” said Paul Ricard, forest health program coordination for the state Department of Environmental Management (DEM).

Worst hit are oak and other hardwood trees in rural regions such as North Smithfield, Smithfield, Coventry, Glocester, Cumberland and West Greenwich. Urban areas, so far, have been spared.

The outbreak is most troubling because it comes just as trees were recovering from the damage inflicted by the winter moth, which defoliated hardwood trees across the state. The gypsy moth caterpillar started appearing around Memorial Day weekend, the exact time the winter moth finished making Swiss cheese out of deciduous tree leaves.

The number of gypsy moths was small at first, Ricard said, showing up in small pockets as they do most years. During the Past week, however, the gypsy moth caterpillar population exploded statewide and is hitting trees with another round of intense leaf-eating.

To make matters worse, there is nothing the state or tree owners can do to halt the damage. Had there been advanced warning, the state could have sent out public warnings and broadcast preventative tips, such as adding barrier capes around tree trunks.

Most of the damage is already done, as the moths are nearing the pupal stage, which begins in July. For preventative steps to work, they need to begin in the fall.

Ricard advises the public not to cut down trees that look like they have little or no leaves remaining.

“Healthy trees can survive years of defoliation,” he said. “Trees are very resilient. They have been around a long time.”

Drought, however, can be a death knell for a defoliated tree. Richard suggests watering damaged trees if they go a week or more without an inch of rain.

It can’t hurt to pull the caterpillars off trees, as well, he said. Caterpillars feed at night when they are less visible to predators, and can be seen climbing tree trunks in the evening.

It’s too late for aerial spraying, but it’s not to early to plan for next year when the gypsy moth may return, Ricard said.

“If there is ever going to be (spraying), it’s going to take political backing and it will help to take action between now and next spring,” he said.

Unlike the spraying done in the 1980s, the spray used today is less toxic. Bacillus thuringiensis kurstaki (Btk) is a naturally occurring bacteria that kills moths, and causes nothing more than eye irritation in humans.

The black caterpillars don’t bite but some people develop a rash from their hair that can last four to five days. The caterpillars’ tiny black droppings also create a sticky nuisance for lawn furniture and parked cars.

It’s not easy to know if the gypsy moth will return next year, but they can survive in extremely cold weather and snow.

For now, Ricard is answering the nonstop stream of phone calls from a worried public. “It's taken everyone by surprise,” he said.