Variable oakleaf caterpillars defoliating white oaks

Variable oakleaf caterpillars defoliating white oaks
Information forwarded by Cindy Garner, Patrick Byers & Lisa Bakerink

Southwest foresters: Heads up. I received a report from a landowner (Brenda Johnston) near Powell in McDonald County of a large population of the variable oakleaf caterpillar defoliating white oaks. I confirmed it from photos she sent. It’s the same as that one caterpillar you showed me last week, Cindy, when we were down there. The landowner also said that there is so much frass dropping that it sounds like rain day and night. She says she has about 80 acres of mostly white oak that is “being ravaged.” And there are quite a few of the large ‘caterpillar hunter’ beetles present. They climb trees and prey on caterpillars; we often see large numbers of those with caterpillar outbreaks.

If you get more reports of outbreaks of this defoliator, please let me know.

Variable oakleaf caterpillars vary widely in appearance having different patterns of red and green, but they all have a tiny black and white ‘racing stripe’ on the side of the head.

See these photos:
http://www.biosurvey.ou.edu/okwild/misc/vocat.html
http://bugguide.net/node/view/418

We occasionally get outbreaks of this caterpillar in mid-summer feeding on many hardwoods, but it prefers white oaks. And there are often other species of caterpillars, various species of oakworms, that are found along with them defoliating the same trees.

Here is more detailed information: http://na.fs.fed.us/spfo/pubs/fidls/variableOLC/voc.htm

Here is info about the caterpillar hunter, the ground beetle that is preying on them, but unfortunately does not usually provide enough control. We sometimes get calls from folks who have seen all these big green beetles, but have not yet noticed the caterpillars.
http://www.uark.edu/ua/arthmuse/cathunt.html
http://www.uky.edu/Ag/CritterFiles/casefile/insects/beetles/ground/ground.htm

Rob Lawrence
Forest Entomologist
Missouri Department of Conservation
3500 East Gans Road
Columbia, MO 65201

Tel: 573-815-7901, ext. 3946
E-mail: Rob.Lawrence@mdc.mo.gov