Texas Parks & Wildlife Magazine   


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Wild Thing: Transformed

Southern flannel moths start out as bad-boy puss caterpillars.

By Ben Hutchins

You won’t soon forget the pain caused by the puss caterpillar (Megalopyge opercularis), or asp, as it is often called in Texas. Indeed, the venom regularly sends Texans to the hospital with swelling, burning and blisters or more severe symptoms. Populations fluctuate dramatically from year to year, but reported stings increase in summer months.

However, the much-maligned puss caterpillar, sporting a mohawk that seems to reinforce the troublemaker label, is far from public enemy No. 1. At most, the puss caterpillar is unintentionally a juvenile delinquent. As a reformed adult, the puss caterpillar is transformed into the harmless and beautiful southern flannel moth.

After the puss caterpillar hatches, it grows quickly, feeding on a variety of trees and shrubs, especially favoring oaks and elms. As a larva, the puss caterpillar does not seek out unwary victims to sting. Rather, the sting is an involuntary defense that happens only when an unknowing person, raccoon, bird or other potential predator grabs the animal, causing the venom-filled hairs to penetrate and break off inside the skin. The caterpillar teaches a painful lesson to look carefully before touching.


Six or seven weeks after hatching, the puss caterpillar spins a cocoon and pupates. Depending on when the caterpillar hatched, pupation could take two weeks or several months. Coarse, venom-filled hairs are replaced by the thick covering of long, fine (and harmless) hairs that give the southern flannel moth its name. The wings can be variable among individuals but consistently display a gradient that runs from rich, almost black-brown in the front, through rust-red, orange, yellow and cream in the back. Fine, wavy white streaks add contrast. The southern flannel moth also sports black “boots” on the ends of its legs. Most noticeably, the entire body and upper legs are covered by that burnt-orange to nearly cream-colored, cotton-candy-textured hair.


As an adult, the southern flannel moth is short-lived. Within a couple of days of hatching, the female lays her eggs. Neither the male nor the female adults feed, so within about a week, they die. Although the sting of puss caterpillars warrants respect, remember they’re just trying to thrive until their beautiful but brief adulthood.  

Common Name
Southern flannel moth

Scientific Name
Megalopyge opercularis

Scrubby deciduous shade trees such as oaks, elms, maples and citrus, or on small bushes.

Various shrubs and bushes, such as hollies.

Did you know?
Instead of the usual five prolegs of most caterpillars, those within the flannel moth family (Megalopygidae) have seven.


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See more wildlife articles on TP&W magazine's Texas wildlife page

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