A rare caterpillar/moth for southwest MO
Article and photographs by Dr. Thomas J. Riley
Last week I found this 2 1/2 inch-long caterpillar crawling across a path in Cedar Creek, MO. At first I wasn’t sure what it was, however it looked familiar to me. I knew it was the larva of a Saturniid or silk moth. It looked similar to an io moth caterpillar in shape, size, and spine configuration but the color was totally different. Then I realized I had seen many of these before in Louisiana and that it had to be the larva of the Buck Moth, Hemileuca maia http://bugguide.net/node/view/471
When I lived in Baton Rouge Louisiana these were very common every spring. I knew they occurred in the Missouri Ozarks, but have never seen any since moving here 8 years ago.
This caterpillar/moth is an unusual find in MO, and it also has an unusual life cycle. The black and white moths emerge in October and November and can be seen flying about on sunny days, even when there is frost on the ground and the temperature is around freezing! The moths do not feed. Their role is to mate and lay eggs. They do this on oak trees, producing a mass of eggs that encircles a small twig. The eggs are the over-wintering stage for the buck moth. Once spring arrives, the warmer temperatures and increasing day length stimulate the eggs to hatch in synchrony with the growth of spring foliage on the oaks. The larvae feed communally until they reach the third instar after which they disperse to feed as solitary caterpillars. When full grown, the caterpillars crawl down from the tree and pupate in the soil and leaf litter. This is how I found the caterpillar in my photos. When I put it in a container with some soil, it immediately burrowed in and pupated.
I will have to wait and see if it survives until fall. In Louisiana many of the caterpillars I tried to rear were parasitized by Tachinid flies.
If you find one of these wandering, dark colored, spiny caterpillars, handle it with care as the small yellow-orange spines running down their back can give you a painful sting.
In Louisiana the caterpillars were common every spring and very well know as “Stinging caterpillars”. I was told that the name Buck Moth came about from the moths being on the wing during deer = buck season.
In the south the caterpillars eat the foliage of Live Oaks. Here, according to Heitzman & Heitzman, in Butterflies and Moths of Missouri, they are associated with scrub oak in the Ozark region of Missouri.
Thomas J. Riley,
Ph. D. Professor [retired] of Entomology
Louisiana State University