Editor’s note: Elgin residents have been reporting an influx of these furry, freaky one-inch critters in the last week. They may seem harmless, but they are in fact one of the most venomous caterpillars in the United States. Here’s the scoop on these weird little dudes—and what to do if you get stung by one.
Southern Arizona is renowned for its seemingly endless lineup of creepy crawlies and even plants that can inflict various levels of harm on our tender flesh. Hence the popularity of my class – Thorns, Stingers, & Fangs – Welcome to Arizona! People generally want to know what can harm them in the wild, how to avoid getting hurt in the first place, and what they can do should they run afoul of a particular species. Many people would be reticent to list caterpillars as a source of harm, yet a good handful of butterfly and moth larvae possess “urticating hairs.” Named after the genus Urtica, which houses a number of stinging nettles species, the term immediately connotes pain.
I have personally experienced stinging episodes with a number of different caterpillars, some of which felt like a paper wasp. Still, this falls far short of the outright excruciating agony that a Puss moth caterpillar can inflict via its venomous spines. Severe reactions can occur among sensitive individuals, who may experience radiating pain or even life-threatening anaphylaxis. While I have yet to have the pleasure, those stung by the caterpillar’s hairs liken the pain to that induced by blunt force trauma or a broken bone! Clearly, these strange moth caterpillars do not want to be eaten, their hairs acting as an extreme defense against most predators.
Puss moth caterpillars are so densely covered in hairs that they look a bit like a miniature version of Cousin Itt from the Addams Family—minus the sunglasses. My rule of thumb is if a caterpillar has any level of hairiness, from dense to sparse, then I might well get stung if I touch one. Most people run afoul of Puss moth larvae when one falls onto their flesh or clothing. Even a slight brush against the skin suffices to trigger toxins from the hairs.
Given their diet of leaves from a wide range of trees and shrubs, puss moth caterpillars can show up just about anywhere in the Sky Islands, though especially in wooded environments. Like many other local invertebrates, they can have relative outbreak years where their numbers increase, necessitating greater awareness on our part.
Puss moth caterpillars have a fairly typical moth life cycle. The pupae overwinter in a cocoon from which adults emerge in late spring or early summer. After mating, the adult moths lay eggs on plant leaves. Tiny whitish, fuzzy larvae hatch from eggs and develop through several stages or instars over a period of many weeks before pupation.
My advice is to enjoy the outdoors, while keeping a cautious eye out when you are near trees or shrubs. Try to avoid brushing up against foliage and wear a wide-brimmed hat so that a falling caterpillar is unlikely to land on your bare skin. Also, carefully shake out your clothes after a hike to ensure you did not bring along an unwanted hitchhiker.
Look carefully at the photo and form a search image that will help you to identify a native species that is best admired from afar. Should you get stung, despite precautions, take it seriously and take action. Try to remove any attached caterpillar hairs with tape. Clean the wound site with soap and water. Apply an ice pack to reduce pain. You can even immobilize the affected limb, if feasible. Be aware, don’t worry, and enjoy the wilds!
Vincent Pinto and his wife, Claudia, run Ravens-Way Wild Journeys, their nature adventure and conservation organization devoted to protecting and promoting the unique biodiversity of the Sky Islands region. RWWJ offers a wide variety of private, custom-made courses, birding and biodiversity tours. Visit ravensnatureschool.org