University of Maryland Extension

Saddleback Caterpillar

Carolyn Puckett
Saddleback Caterpillar

Photo by Gerald J. Lenhard, Louiana State University

Did my beans just sting me?

If you were working on your beans and felt a sharp sting, you may have touched a saddleback caterpillar, the larvae of the slug moth (Acharia stimulea).

The saddleback caterpillar has a distinctive color pattern, dark brown on the front and end sections with a bright green “saddle blanket” outlined in white and topped by a brown “saddle” in the middle. It also sports four venomous protruding spikes or horns. The insect is native to the eastern United States and may feed on a wide array of host plant species, including beans, iris, sunflowers, blueberries, sweet corn, and grapevines.

The insect is not a significant horticultural pest, but the potent venom can cause a severe medical reaction in some people. The horns embed deeply into the skin and break off. In addition to the intense burning sensation that can last for hours, some people may experience migraines, gastrointestinal problems, or even anaphylactic shock. Should contact occur, remove the spines right away as the longer the spines are embedded in tissue, the more venom is released. While ice packs and over-the counter-medications may help with the pain, victims with more severe reactions should seek medical attention promptly.

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