Caterpillars vulnerable in their egg cases
June 25, 2008 · Updated 1:11 PM
"Jim O'Connor climbs through a decorative tree in Langley, looking for caterpillar egg cases.JIm Larsen / staff photoOrchardists who dread the tent caterpillar season can largely nip the problem in the bud if they act soon.Not in the bud, exactly. But on the branches, where caterpillar egg cases are craftily camouflaged to deceive predators. They look like a small bump on the branch, but a trained human eye can easily spot them.Jim O'Connor, a veteran gardener on South Whidbey, and his crew can often be found in the trees this time of year, flipping caterpillar egg cases off the branches.It's so easy, said O'Connor. Just pop them off the branches right now with your finger.Accurately predicting the caterpillar population is as tough as making long-term weather forecasts, but just as hard to resist. On Whidbey Island, wild alder trees and domestic fruit trees are sometimes covered with the silky tents that contain the greenish-yellow leaf munchers. One year in the mid-'80, they were so prevalent that millions fell onto the roads, giving a green sheen to many a country mile.From what O'Connor has seen to date, this might be a bad year for caterpillars. He said his crew spent only 45 minutes in one orchard and disposed of more than 1,000 egg cases.We have just a few weeks left before the thousands of caterpillar egg cases that we have been finding turn into those unwanted tents, he said.Island County WSU Extension Agent Don Meehan has been been helping islanders battle tent caterpillars for two decades or more, and he concurs with O'Connor that the time to start the fight is now.Just pop 'em off, Meehan said of the egg cases. It's one of the easiest controls in terms of fruit trees. The method does not work on the island's many towering alder trees, he noted.Meehan described caterpillar egg cases as looking like shiny gray Styrofoam. They make a small, elongated bump on the branch. Pop one off and underneath you can see a honeycomb-like structure, with each compartment containing a caterpillar egg.Meehan said once the caterpillars hatch it's too late if they remain on the tree's branches -- they go right to work destroying leaves. The new worms have to find food immediately, so they'll die on the ground, he said.For those who can't attack the egg cases, Meehan recommends spraying an organic agent called BT just as soon as the caterpillars hatch. When they're small they're really vulnerable, he said.O'Connor says that the more egg cases disposed of, the less pesticide will be needed. It's easier than dousing ourselves with pesticides later -- organic or not, he said. "