Caterpillars threaten maple trees
The Associated Press | May 24,2006
HUNTINGTON — Forest tent caterpillars are threatening Vermont's maple and other trees this spring, and rain has kept sugarbush owners from fighting back with the biological insecticide some would like to use.
Vermont is in the midst of a cycle — expected to last three to seven years — in which the caterpillars are proliferating.
Last year — the bugs, less than a half inch long, blueish in color, with a white, keyhole-shaped spot on their backs — defoliated 230,000 acres of Vermont's forests.
The bugs will feed on the leaves of a variety of deciduous trees, but it's the sugar maples that support Vermont's $225 million maple syrup industry that are the biggest cause for worry.
"We're going to be hit again," said David Mance of Shaftsbury about a sugarbush that lost 40 percent of its leaves by last June due to a forest tent caterpillar infestation.
Mance said that loss was despite his use of Bacillus thuringiensis kurstaki, or Btk, a biological insecticide he had sprayed on his trees.
Wind and rain make the insecticide ineffective, so Mance and other sugarmakers have been unable to use it this month, the wettest May on record in Vermont.
And this is time of year to use Btk, before the bugs have a chance to eat the new leaves.
Foresters predict what areas will be hit hardest by caterpillars by examining masses of eggs on trees during the winter.
This year, the Champlain Valley and southern Vermont are expected to see the biggest problems.
Trees can survive when insects eat their leaves, but a complete loss of summer leaves can weaken their ability to resist sometimes fatal diseases.
A key to maintaining the health of trees during an infestation is handling them with care, state foresters say.
Even trees that were to be left standing can be disturbed by logging, so that should wait until the bug cycle declines.
Same goes for excavations near affected trees.
Scaling back or even stopping sugaring during infestations also can help.
Scott Pfister, forest resource protection chief for the state Department of Forests, Parks and Recreation, said the situation is not hopeless.
If history is any guide, disease and parasitic flies will attack the caterpillars and their population will decline steeply after a few years.