By Stephen Janak, County Extension Agent – Ag/Natural Resources
They’re everywhere! They’re in your trees, on your house, in your flowers, and, inevitably, on your face. They string their webs up and down trees, across rooftops, and even hang on long strands from tree branches. What are they? I honestly can’t tell you the exact species name, because I haven’t gotten results back from the Texas A&M Entomology Lab. The bottom line is that there are several different species of caterpillars in our oak trees right now, and they’re all from the same family of insects. This means that they can all be controlled, if control is desired, with the same methods.
These caterpillars are eating the leaves of live oaks, post oaks, water oaks, and even crepe myrtles, but rest assured, they will not kill your trees. They are primarily eating the new spring growth on these trees, but not for long. These species of caterpillars undergo only one life cycle each year. In a couple of weeks they will be forming cocoons, and in May they will begin to emerge as moths. Once they enclose themselves in cocoons, the leaf-feeding will stop and trees will start to put on new leaves. Most trees can withstand being completely defoliated two to three or more times per year. The tree will use energy reserves stored in the roots to make new leaves in just a couple of weeks. If a tree should die after this one-time defoliation, that tree was already stressed and on the brink of death anyways.
So what do you do about these pests? It is best, at this point, to do nothing. Spraying a chemical would be a reckless use of pesticides. Sprays such as malathion or carbaryl (Sevin) are broad-spectrum insecticides that can potentially kill beneficial insects as well as the caterpillars. If you absolutely must get rid of them before a backyard party, look for a product containing Bt (Bacillus thuringiensis), a naturally occurring bacteria that targets only caterpillars and poses no threat to beneficial insects, pets, or humans. This pesticide is often used in organic farming. Always read and follow label instructions when using pesticides.
Insect populations cycle up and down naturally. Next year we may have very few caterpillars, or we may have more than this year. Keep an eye out during the first of April next year to determine if and when you may want to spray. Call for more info or with questions: 979-732-2082.