Tussock moth cocoons cause allergic reactions in some, UF expert says
GAINESVILLE, Fla. — Florida’s poison-control centers recently noted an uptick in calls about stinging caterpillars, and now a University of Florida entomologist warns that some people may suffer skin irritation from cocoons that are unusually abundant this year.
The culprit is a tussock moth, known scientifically as Orgyia detrita. Its caterpillars are usually active in March and April, often in the vicinity of oak trees. Touching the furry, black-and-white critters can cause localized swelling, itching, burning and redness. The caterpillar doesn’t produce stinging venom, but its hairs trigger an allergic reaction in some people.
Some of those hairs wind up in the cocoons the caterpillars spin when it’s time to mature into moths, says Eileen Buss, an associate professor and extension specialist with UF’s Institute of Food and Agricultural Sciences. So the cocoons are allergenic, too.
“I’ve heard reports that there are a lot of these caterpillars right now in Tampa, as far north as Jacksonville, and I’m seeing a lot in Gainesville,” Buss said. “Outbreaks seem to be cyclical. I haven’t seen it this bad since 2001.”
And while the caterpillars are eye-catching, the cocoons are nondescript.
The cocoons are fuzzy, tan, football-shaped masses about an inch long. They’re found on everything from tree branches to walls to park benches to recycling bins — which is where Buss encountered one this week, much to her chagrin.
“The itchy, burning sensation started really quickly,” she said.
It’s unclear what percentage of the population is allergic, she said. But the federal Centers for Disease Control and Prevention recently issued a bulletin that indicated between 12.6 and 21.7 percent of children showed symptoms when their Florida day-care facilities had caterpillar infestations.
Over-the-counter hydrocortisone cream may not be sufficient to treat the skin irritation, Buss said, so those affected may need to see a doctor.
Another treatment option is to place strips of adhesive tape over the affected area and then peel them off to remove any remaining caterpillar hairs. Ice can reduce the pain and itching as well.
Residents who find cocoons should not spray them with insecticide, Buss said. There’s little chance it will kill the developing moths, and it’s unlikely to have any effect on their allergenic properties.
Instead, she suggests removing the cocoons — but only after donning protective clothing, such as long pants, long-sleeved shirts, closed-toe shoes, gloves and a hat.
“You want to minimize the amount of exposed skin,” Buss said. It may be best to use a stick or a tool to scrape the cocoons loose, she said.
After removal, cocoons should be put in a plastic trash bag and put out for waste collection, Buss said.
Another potential benefit of removing the cocoons: It could help reduce local populations of the tussock moth. Buss explains that with this species, adult female moths are wingless, and they lay eggs on their own empty cocoons. By removing cocoons promptly, homeowners can also remove new, unhatched eggs — and this year, that could be helpful.
“This species usually produces one or two generations per year,” she said. “I think maybe the warm winter got them started early, so maybe we’re going to have a second generation in a couple more weeks.”