Adults emerge in August or September and deposit eggs on the bark on the lower truncks of ash trees. The caterpillars that hatch from the eggs then bore through the bark and feed within the branches and trunks of the trees. There is one generation each year. Cottonwood and ash are the preferred hosts, but this insect will attack many of other shade and fruit trees, and shrubs. Adult moths are active from June through July.
Female moths deposit their eggs on the bark of trees, usually on the lower trunk.
After hatching from the eggs, young carpenterworms tunnel directly into the inner bark and later bore into the heartwood. Heavily infested trees are structually weakened and may be broken during high winds. The caterpillars require more than one year to complete their feeding and may be up to 2 inches long at maturity. This should be used as a preventative treatment before the larvae bore into the tree. Depending on the specific borer, spray applications could begin the first of May up to the first of July.