The toxic toupee (Megalopyge opercularis). Although they’re only 1″-1.5″ in length, these adorable balls of fur are the most venomous caterpillars in the United States.

The Toxic Toupee

The Toxic Toupee. Photo by: Awwducational

The toxic toupee, aka the furry puss caterpillar, aka Donald Trump, is the larval form of the southern flannel moth.

southern flannel moth

Sourthern flannel moth. Adult form of toxic toupee. Photo by: Patrick Coin

That's not a coat. They may look cute, but petting this adorable ball of fur can land you a trip to the hospital. They are covered in hollow, hair-like bristles called setae. At the base of these setae are a venom which, as described by patients, feels similar to a broken bone when they sting. Symptoms include pain, swelling, headache, shock-like symptoms and even convulsions. Symptoms can still be felt 24 hours after the envenomations. Although no deaths have been reported, the pain suffered by patients led doctors to believe that death is possible from the sting. The larger the caterpillar, the more toxic the stings.

M. opercularis can be found in New Jersey all the way down to Florida and westward to Arkansas and Texas. They typically feed on elms, oaks, palms, holly and other woody plants. The adult form of the southern flannel moth does not have the venom.

Poo flinging

Megalopyge opercularis feces throwing

Video Source:

Another rather bizarre fact about the toxic toupee is that they fling their poo.  As you can see, it's not just a gentle toss. They can eject the poo more than 1.5 meters, or 38 times its body length! According to research by Martha Weiss and published in the journal Ecology Letters, the most likely reason for this behavior is to keep predators away.

Sources/Further Reading

Weiss, M. (2003). Good housekeeping: why do shelter‐dwelling caterpillars fling their frass?. Ecology Letters, 6(4), DOI: 10.1046/j.1461-0248.2003.00442.x

Hall, D. W. (2012, November 12). Puss caterpillar (larva), southern flannel moth (adult ... Retrieved October 23, 2016, from

Foot, N. (1922). PATHOLOGY OF THE DERMATITIS CAUSED BY MEGALOPYGE OPERCULARIS, A TEXAN CATERPILLAR. The Journal of Experimental Medicine, 35(5), 737.  10.1084/jem.35.5.737

McGovern JP, Barkin GD, McElhenney TR, Wende R. Megalopyge OpercularisObservations of Its Life History, Natural History of Its Sting in Man, and Report of an Epidemic. JAMA. 1961;175(13):1155-1158. DOI:10.1001/jama.1961.03040130039009


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