They may look cute and furry, but puss caterpillars have one of the most painful stings of any insect in the state. Folks who are stung on a leg often experience pain extending into the groin, while folks who stung on an arm may report pain radiating through the armpits and across the chest, far from the point of contact. Victims are sometimes rushed to the hospital thinking they are having a heart attack, and patients are sometimes held in the hospital overnight. But these are the extremes, and the pain varies greatly, with many victims experiencing only mild stinging at the point of contact. Of course, much of this variation depends on the size of the caterpillar and just how much contact it had with the skin.
Fortunately, puss caterpillars are not very common and severe sting events even less common. The stings come from hollow spines with venom glands at their base that are hidden beneath that coat of harmless longer hairs. These caterpillars don’t attack people like a bee or wasp might; stings only occur when caterpillars are accidentally pressed against the skin. Mature puss caterpillars are about one inch in length. There is usually a pointed “tail” of hairs at the rear end, and the head is carried beneath the body, making it difficult to spot.
Puss caterpillars feed on a wide range of plants, including oaks and other hardwoods, fruit trees and many shrubs. Although caterpillars occur throughout the state, they are rarely seen. Occasionally there are local outbreaks with caterpillars becoming so numerous they cause serious defoliation to landscape shrubs such as azalea and yaupon holly. The moths, known as southern flannel moths, are even hairier than the caterpillars. Even their legs and abdomens are covered with long, fine hairs. But the moths do not sting.
Other stinging caterpillars in the state include buck moths, Io moths, saddleback caterpillars, stinging rose slug, crowned slugs, hag moths and a few others. Most caterpillars do not sting because they do not have venomous spines, and many caterpillars that have spines and look like they could sting are harmless. Hickory horned devil caterpillars are a good example of a caterpillar that looks fierce but is harmless. There are also a few hairy caterpillars that do not have spines, but their hairs can break off and cause irritation if they contact sensitive skin. Forest tent caterpillar and tussock moths are two examples of caterpillars with these fine urticating hairs. You may be able to handle such caterpillars without experiencing much problem, but let one drop down the back of your shirt and wander around a while and you may develop an uncomfortable rash. Children seem to experience these problems more than adults.
Control: When it is necessary to control heavy infestations, puss caterpillars can be quickly and easily killed by spraying with pyrethroid insecticides containing active ingredients such as bifenthrin, cyfluthrin, gamma-cyhalothrin or permethrin. But be aware; dead caterpillars can still sting.
Blake Layton, Extension Entomology Specialist, Mississippi State University Extension Service.
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