State hopes worst of caterpillar infestation over for hardest hit

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(Host) The forest tent caterpillar continues to chew its way northward through Vermont this summer.

But state officials say they hope the hardest hit areas of defoliation have seen the worst of the infestation.

VPR’s Steve Zind reports:

(Zind) For the last several years forest tent caterpillars have made their presence known by swaths of brown and bare trees shorn of their leaves. The state has been tracking the insects and officials expect the caterpillar problem will eventually subside. First of all, time is on their side because the infestations run in cycles. Secondly, they’re getting help from an insect that’s been dubbed the friendly fly’.

(Pfister) “Simply because it is big, it lands on you, you can swat them, they don’t seem to move away. So whenever you have a population explosion of the forest tent caterpillar the friendly fly population also explodes.”

(Zind) Scott Pfister is Chief of Forest Resource Protection for the Department of Forests, Parks, and Recreation. Pfister says the larva of the friendly fly is a parasite that feeds on the tent caterpillars.

Southwestern Vermont has been hardest hit by the infestation. Last year caterpillars were dropping from trees in Manchester and littering the sidewalks underfoot. Pfister says there’s still quite a bit of defoliation visible in the area this year, but because the infestations tend to run in three year cycles, the worst is probably over.

(Pfister) “We’ve also seen a great amount of parasitism by the friendly fly, so we’re pretty optimistic that we’re going to see a collapse in the forest tent caterpillar this year in southern Vermont. We are seeing an increase, especially in central Vermont. Right now if you drive 89 from Montpelier to Burlington, all the hillsides on the south side of 89 are starting to see a lot of defoliation and browning.”

(Zind) The state has been helping sugarmakers by spraying trees to kill the caterpillars. This year the state treated 5,500 acres, four times the area sprayed last year. Most of the cost was paid by the federal government, but Pfister says there’s little money available for future spraying.

Officials are also encouraging woodlot owners to cut back on the timber harvested in infested areas in order to avoid stressing trees.

Pfister says there’s nothing unusual about the current outbreak of forest tent caterpillars and that, eventually the trees will recover with no lasting damage.

For Vermont Public Radio, I’m Steve Zind.

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