Out of the Woods

Photo from North Carolina Forest Service Archive, Bugwood.org

Unpack your suitcase. Cancel the movers. Spanworms—those disgusting black caterpillars that have plagued St. John’s lush maple trees and the people walking under them each of the past few summers—may finally be on their way out of town according to Entomologist, Dr. Peggy Dixon, a span worm expert at the Federal Government’s Cool Climate Crop Research Centre on Brookfield Road.

It was a perfect storm of spanworm-friendly conditions, according to Dixon, that allowed for the initial outbreak about ten years ago: the right climate, a lack of predators, and the maturation of their favourite food—the maple tree. Now their normal life span (8-10 years) has run its course, our miserable cold and wet June-uary may have killed off a lot of remaining young caterpillars, and the ongoing spraying of Btk—a bacteria-based pesticide—has left the spanworm population dwindling.

There may still be some spots around town with a few hangers on–like those Japanese submariners who didn’t know the War was over–but it will be nothing like the height of the outbreak from 2003-2009.

Are we out of the woods for good?

Not for good, says Dixon, but at least for a while. “The spanworm native to eastern North America, not introduced, and there have been outbreaks in New England since the 1800s,” she says. “They occur every 40 years or so.”

So it is safe to go outside for now, but will it be for our children’s children? We’ll have to wait a while and see.

One comment

  1. Emma · November 15, 2010

    I’ll reserve my relief until September. That’s when they’re usually the worst. There’s one tree across from Burton’s Pond that gets so bad I shudder when I walk under it any time of year. Euggghh.