Puss caterpillars may look harmless, but they pack powerful sting

Published 12:00 am Sunday, October 19, 2008

Joe Richardson stopped by the Extension office the other day carrying a wire-mesh cricket tube. You know — the kind of container one uses to carry crickets bream fishing. He wanted to see if I could find out what kind of critter he had captured and put in the container. Evidently, Richardson had an unpleasant encounter with the little furry monster and he wanted to find out exactly what it was.

Richardson proceeded to tell his story while I dumped out the grass, leaves and other biomass from the cricket tube. He had been bush-hogging when this ‘thing’ got on his left wrist, just behind the palm of his hand. Almost instantaneously, he felt a radiating pain move up his arm and into his chest. His arm became swollen and turned red. Needless to say, he was worried. There was also evidence of several puncture marks where the critter stung him. He wondered if the pain were so intense to an adult, how it might feel to a smaller person or to a child.

After a bit more shaking of the cricket tube, out plopped an inch long, furry caterpillar completely covered by thick tan hairs that tapered toward the back end. At first, it was hard to tell the head from the tail until the caterpillar raised his head and moved. The head and legs are really not visible when viewed from above.

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Now, I’ve seen several other species of stinging caterpillars, like the saddleback caterpillar and the hag moth larvae, but this one was new to me. I had to get a quick confirmation on this little critter with a call to our Extension entomologist, Dr. Blake Layton.

Layton informed me that Richardson had had a run-in with and had brought in for ID a puss caterpillar or asp — Megalopyge opercularis. It is the larvae of the flannel moth. Under its long body hairs are shorter spines that discharge venom upon contact. Obviously, envenomation by these critters is very painful and something one should avoid if possible.

In addition to the kinds of symptoms Richardson described, Layton said these caterpillars can also cause welts, hives, numbness, rashes, blisters and muscle spasms. They overwinter in the cocoon or pupal stage and the adults emerge in early summer. The moths lay their eggs on a wide range of plant leaves. The tiny fuzzy larvae hatch from the eggs and develop through several stages or instars between molts over a period of several weeks before they pupate.

Puss caterpillars appear to be much more common in central Texas than they are in Mississippi and numerous human exposures to their stings get reported to the Central Texas Poison Center each fall. Richardson’s critter made a nice conversation piece for a couple of days, but I am glad we don’t have many of those around here.

Reminder: Private Pesticide Applicators’ Certification Training and Exam will be at the Extension office on Monday from 9 until noon. Certification is required to purchase and/or use restricted-use pesticides. Cost is $10 per person.

John C. Coccaro is county Extension director. Write to him at 1100-C Grove St., Vicksburg, MS 39180 or call 601-636-5442. E-mail him at jcoccaro@ext.msstate.edu