What Are These Worms In The Trees?

Spring Cankerworm

Perhaps you have been noticing the creepy worms hanging from your trees lately, or maybe you've even done the eye-catching "GET OFF ME!" dance when one fell in your hair. If so, you may be wondering just what these things are.

These little caterpillars have many names, mostly describing how they move or look. They move by inching along, giving them the names inchworm or measuring worm; the loop their bodies form as they move gives them the name oak looper; and their habit of rolling up into leaves for protection gives them the name leaf roller. They are also known as spring cankerworms. At my house, we call them inchworms.

They usually live on oak trees, but can also infest pecans and other trees. They are more of a nuisance than a dangerous pest, because although they can strip a tree of leaves, a healthy mature tree can easily recover if you give them a little extra water and fertilizer. Wasps and birds are their natural predators. 

The inchworm is actually the larva of a small, dull-colored moth that lays its eggs in cracks in the tree bark. The larvae emerge in March and spend their time eating the newly emerging leaves, using their webs to move from tree to tree. Around the end of April, the caterpillars drop to the ground to pupate, merging as adults in late April and early May. Only the male moths fly, leaving the females to crawl to a tree and lay her eggs, beginning the cycle again. 

To read more about these fascinating insects, visit the Texas A&M Agrilife Extension website. And fear not, they will be gone soon.