2009.04.28
Spotted on I-81: Leaf-eating worms
White caterpillar nests cling to trees along Interstate 81 between the Roanoke and New River valleys.
Based on a reporter’s description of the nests, Eric Day, who manages the insect identification lab at Virginia Tech, said he suspects the Eastern Tent Caterpillar is active.
Just as a stand of flowers or shrub may pop with a huge display some years, so, too, do insect species. Day said scientists expect to see an “outbreak” of the tent caterpillar once every 11 years; the outbreak may span several counties.
There are no reported outbreaks in Virginia. But it’s possible for an area as small as a couple miles of roadside to experience a caterpillar population boom that falls short of a reportable outbreak. That may be what’s happening along the interstate, he said
Motorists can easily spot the white patches amid the green canopy. But even where the worms are thriving, not every tree is involved. The tent caterpillar favors black cherry, chokecherry and apple, and also feeds on hawthorn, pear, plum and flowering fruits.
What’s at risk? The worms eat leaves by day and return to their web-like shelters at night, causing defoliation. However, new leaves will grow back. By June, you’ll hardly notice where the insects feasted, according to Day said, who said often no control is needed.
Horse owners may want to take notice. Day is aware of a past association between foal deaths and large populations of the caterpillars. He advised reading this 2007 cooperative extension piece that explains why “controlling Eastern Tent Caterpillars is vital to area horse farms.”
-Jeff Sturgeon
