COLUMBUS, OH - White oak trees throughout a seven-county area of southern Ohio suffered moderate to severe leaf loss this spring thanks to the voracious appetite of several caterpillar species, according to foresters with the Ohio Department of Natural Resources (ODNR).
Most of the damage occurred in Gallia, Jackson, Lawrence, Pike, Ross, Scioto and Vinton counties, said state forest biologist Dan Balser, with the ODNR Division of Forestry. Two of the hardest-impacted areas are near Portsmouth and between Waverly and Chillicothe.
Our staff reports, along with calls from landowners, indicate that most white oak trees in infested areas suffered from moderate to extensive leaf loss from these voracious caterpillars, said Balser. Fortunately, the worst of the defoliation appears to be over as many of the caterpillars have advanced in their life cycle.
A similar infestation is harming oaks in parts of West Virginia and Kentucky.
Several caterpillar species are responsible for the damage, including the common oak moth and caterpillars in the genus Phigalia. The high concentration of these native caterpillars was most likely triggered by last years drought, according to Balser, who added that the insects produce only one generation a year.
State foresters say if trees were healthy prior to the damage they will likely recover. However, trees previously stressed by weather conditions, insect or disease problems will have a harder time maintaining their health.
A critical factor impacting the oak trees ability to recovery is how quickly they can re-grow leaves, which help them store the necessary energy to survive the winter, said Balser. There really is little property managers can do other than closely monitor their trees.
If drought conditions or other stress factors further impact trees later this year, state foresters expect some tree mortality will result.
Phigalia caterpillars are highly variable in color and move with the typical tail-to-nose movement of an inchworm. In addition to oaks, they also feed on a variety of hardwood hosts such as maple, wild cherry, elm and hickory.
The common oak moth, Phoberia atomaris, is also a native insect. It is nearly an inch long when mature, hairless, and generally dark brown and black. They have two rows of small, black triangles that occur down the length of the back of the caterpillar. The common oak moth was numerous and caused extensive damage in Ross County last year. This pest prefers to feed on white oak. Natural predators and parasites typically control this caterpillar after a couple of years.