Caterpillar infestation

Asked August 17, 2016, 2:43 PM EDT

Hello We live on a wooded lot with primarily oak trees. At this time of the year we are inundated with caterpillars which I believe are tent caterpillars. They are high in the oak trees, and for 2-3 weeks their droppings,which resemble round pellets, fall continuously on our driveway, lawn furniture, patio.etc. How can these be prevented? Can we have a tree company spray the trees surrounding our house? And how can we clean up the droppings, thy are difficult to clean up by hose or leaf blower. Thank you

Howard County Maryland pest control orange striped oakworm insect

1 Response

Based on your description this sounds like the orange striped oakworm. This is a late season pest that feeds on oak and other tree species. Defoliation usually occurs one branch at a time when populations are small.

Mature larvae are about 1 1/2 inches long. They are black with eight orange stripes and two black spines behind the head. Look for clusters of caterpillars feeding near defoliated areas. Jar the branches and some may drop to the ground making collection and identification easier. The caterpillars feed in clumps on the ends of branches. Older caterpillars are defoliators. You can prune out branches or knock them down with a pole pruner to make collections easier. Drop into a bucket of soapy water.

It is late in the season and usually by this time of year the trees have stored enough energy to be able to take the defoliation in stride. There is an ichneumonid wasp that parasitizes this caterpillar. No control is recommended. Caterpillars are walking around looking for a place to pupate.

Next season start monitoring for this pest from June through September looking for defoliation. You can manually destroy young larvae on small trees. If you have a large infestation, you can spray with Bacillus thuringiensis, a biological control that affects only the caterpillars and not humans or non targets that are not caterpillars. The caterpillars need to be under an inch for good control.
No easy answers for removing the droppings - sweeping, hose, or leaf blower.