We’ve got some hungry caterpillars around here, but they’re not Eric Carle’s caterpillars. Remember his story, The Very Hungry Caterpillar? That little cutie eats more and more food all week long until Saturday when he puts away so much junk food that he ends up with a tummy ache. What happens Sunday? He eats one big green leaf and is all better, builds a cocoon, and turns into a beautiful butterfly.
All caterpillars are generally voracious feeders (they’ve been described as “eating machines”) and they’re usually “herbivorous,” or plant-eating. Carle’s idea for his story was a good one.
Our tent caterpillars,, herbivorous and extremely voracious eaters, don’t turn into beautiful butterflies, however. Every 10-12 years or so, we have an invasion and they can defoliate a tree in less time than it takes to read The Very Hungry Caterpillar–or so it seems. They especially enjoy birch, alder, willow, ornamental and fruit trees, as well as rosebushes.
Instead of building cocoons, they build silky tents in the trees where they hang out at night. They spend their days munching on new green leaves. A friend’s daughter, Lisa Iaroslavtsev, shot this great photo on Marrowstone Island a few weeks ago.
We go into lock down mode when we see an invasion on the horizon. It generally lasts two to three years, although they’re only feeding on our trees in the spring and early summer, just as the new leaves emerge. The first year is manageable–maybe a nest here and there. This year was a second season for us. I went out every other morning before the caterpillars were out of bed and picked them off with my fingers or clipped off a few small nests, or “tents.” Occasionally I needed to use the long-handled pruner to get a high nest. Next year, unless this was our big year, will be full scale invasion and I’ll do an every morning inspection.
Chemical sprays can harm beneficial insects and birds, but many people use some of the safer biological sprays that have been developed. Some untreated wooded areas become caterpillar jungles. Friends tell stories of caterpillars so thick in a more remote area of our county one year that the roads were brown and slippery with them.
Next winter after the fruit trees are pruned, I’ll go through and look for their egg cases. They look like small gray Styrofoam patches on the branches, easy to peel off and throw in the garbage (they can survive and hatch if left on the ground).
I turned over the alder trees down by the bay to the critters this year. The irony is that by simply letting them live and defoliate the trees, they can run out of meals–and their predators (a small wasp) will develop and then kill them, and the infestation will end. The defoliation doesn’t usually kill the tree, but it can alarm the neighbors.
And it can make us go just a little crazy. Last year when six-year-old Tessa next door proudly showed me her “pet” caterpillar she was carrying around, it was all I could do to not grab it, throw it to the ground, and stomp on it.
Give me a wooly bear any day–now there’s one cute caterpillar!