Wilting buckeyes may sound like an Ann Arbor dream, but I'm not talking about our beloved Silver Bullets. I'm referring to the symptoms caused by the Buckeye Petiole Borer (Proteoteras aesculana) on its namesake host.
The caterpillars of this tiny native moth bore into leaf petioles causing new leaves to droop, wilt, and turn dark green to black. Damaged leaves will eventually detach producing mild defoliation. Symptoms may superficially resemble frost or freeze damage.
Look for a slight swelling, a spot-like discoloration, and a small hole in the petioles of affected leaves. Small quantities of sawdust-like frass (insect excrement) may hang from the hole. Clean holes usually indicate the caterpillars have completed their development and have exited for pupation. Damage by this borer may appear conspicuous; however, the caterpillars seldom cause significant leaf loss, so no chemical control recommendations are currently available.
There are two generations per season in Ohio. Removing and destroying leaves infested with first generation caterpillars will reduce damage caused by the second generation. Unfortunately, all of the petioles I examined yesterday had empty tunnels indicating the first generation has come to an end so hand-picking will have no value. However, hand-picking by our defensive backs will have great value in Ann Arbor in November where there will be no wilting Buckeyes!