Tent Caterpillars

Eastern Tent CaterpillarsHave you been noticing large webs in your trees recently? Although these webs may make your trees look like they belong at a haunted house, they really are nothing to be spooked about.

Enclosed in these webs are hundreds of caterpillars known as Eastern tent caterpillars munching away happily on the leaves of many hardwood trees. Their favorite host trees include wild cherry, hawthorn, and wild plum.  They also seem to enjoy the two pecan trees in my front yard. They can do severe damage to the branches they inhabit for about 6 weeks.  But they will eventually molt into moths and fly away, leaving your trees to recover until next year when the eggs hatch again.

Tent caterpillars will not kill healthy trees, but they can be most damaging and stressful to young small trees. Honestly, more damage is usually done by homeowners trying to kill the caterpillars. We have heard stories of homeowners using torches and gasoline to burn the caterpillars out of trees.  This of course causes irreparable fire damage to the trees and poses a significant safety threat to the person doing the flame throwing. Do not attempt to burn tent caterpillars out of your trees!

Tent Caterpillar Egg Mass

Tent caterpillar egg mass

Depending on the size of the tree, you can prune out branches with tents, preferably while they’re small.  You can even look for egg masses to remove or prune out before they hatch. The egg masses will encircle a twig, almost like a corn dog, and are usually dark and shiny. Another option is to apply Bt (Bacillus thuringiensis) worm and caterpillar killer on and around the caterpillars when they are still young.  Keep in mind the Bt will also be deadly to desirable caterpillars such as butterflies and will not take immediate effect. However, removal is usually not warranted and it’s best to wait for the caterpillars to do their thing and move on to return again next year.