TUSCALOOSA, Ala. – Caterpillars can be cute, are generally soft to the touch, and sometimes even beautiful to behold with intricate, colorful designs.
Plus, they transform into butterflies and moths — insects that even people who find most bugs creepy still tend to appreciate.
Such a delicate critter couldn’t possibly be dangerous, right? Not necessarily. In Alabama, some caterpillars, if touched, can cause people so much pain that they may end up hospitalized.
“The vast majority of caterpillars are totally harmless, but about a dozen or so in Alabama have some sort of stinging capability,” said Dr. John Abbott, an entomologist and chief curator and director of the Department of Museum Research and Collections.
Abbott said these venomous caterpillars are most active in late spring through summer and early fall.
They’re not aggressive, but because they’re generally “fleshy little snacks for all sorts of predators,” some are equipped with urticating hairs, which are hollowed, barbed hairs filled with venom as a defense mechanism.
“If you touch one of these caterpillars, these barbed hairs will stick into you, break off and envenomate you,” he said. “It’s not like a wasp that actively continues to sting you. It’s passive, but it certainly packs a punch.”
All of the caterpillars that sting in Alabama turn into moths.
Amongst the most common stinging caterpillars in the state is the saddleback caterpillar, which is 1 inch long with a green “shirt” on its generally brown bodies and a saddle-looking pattern on its back. Its venomous hairs are gathered in bunches at the end of its body. The pain of its sting is comparable to a honeybee’s.
“Then there are io moths and buck moths caterpillars that are in the giant silk moth family,” Abbott said. “Those are the largest of the ones that sting. They’re covered in very pronounced spines and ornamentations and color patterns that suggest you should be careful.”
The buck moth caterpillar is about 2.5 inches long, and its sting causes immediate, radiating pain, followed by itching, redness and swelling that can last up to a week.
The most dangerous of the stinging caterpillars in Alabama is the asp or puss caterpillar. It doesn’t move much and its colors and design are very bland — it looks like a small blonde, brown or gray wig — but its venom is excruciating.
“They’re called asp caterpillars because the pain of their venom is very painful, conjuring a comparison to that of an asp snake,” Abbott said. “They are often found on the side of trees and bark getting ready to pupate. They often find firewood stacks to pupate and that’s where people encounter them.
“Their sting is very painful and certainly can send you to the hospital.”
Like with any insect sting, reactions can differ from person to person. Some people can go into anaphylaxis and others will just have pain. Abbott advises that if stung by a venomous caterpillar, a person should put duct tape over the area so the barbed hairs can be pulled out. Next, put some ice on the area to reduce swelling. If breathing issues or extreme swelling occur, go to urgent care or the ER.
“As with anything if you don’t know what it is you should stay away from it,” he said. “I don’t want people to be fearful of going outside, but some caterpillar stings can definitely be painful, though the vast majority are not, even the harrier ones.”