Stinging caterpillar season returns to Texas, experts warn against touching ‘fuzzy’ insects

Stinging caterpillars are typically prevalent in San Antonio from March through December

Top left is Hickory tussock caterpillar, top right is Spiny oak slug caterpillar, bottom left is Puss caterpillar and bottom right is Saddleback caterpillar (Jerry A Payne, Wizzie Brown, John Ghent, KSAT)

SAN ANTONIO – Stinging caterpillar season is starting back up in Texas.

Touching certain stinging caterpillar species can cause contact rashes and painful reactions.

“A good rule of thumb is if a caterpillar looks ‘fuzzy’ - don’t touch it,” said Bexar County AgriLife Extension specialist Molly Keck.

Although many fuzzy caterpillars are not dangerous, do not pick up a caterpillar unless you are sure it is not of the stinging variety. The puss caterpillar, for example, looks deceptively soft and can be especially tempting for children to want to pick up or “pet” them, according to a news release from AgriLife Today.

Puss moth caterpillars, also known as asps, are furry and fluffy looking, with different color variations. Touching them can cause a burning sensation and a rash that could be very itchy and may even require a trip to the emergency room, AgriLife Extension experts say.

Species like the buck moth caterpillar, spiny oak slug caterpillar, hickory tussock moth caterpillar, saddleback caterpillar and Io moth caterpillar can also cause painful skin irritations if you touch them.

Janet Hurley, AgriLife Extension statewide integrated pest management specialist for schools, said “since these caterpillars tend to hide, you may not even know you’ve encountered one until you feel the sting.”

If you are stung, you may feel immediate pain and reddish-colored spots may appear where spines entered the skin. Some people may not feel pain until several minutes after they are stung, while others can experience intense throbbing or radiating pain, the news release said.

People will react differently to caterpillar toxins with some developing a more severe reaction than others. Different areas of the body may also have more or less severe reactions depending on the thickness of the skin in the area where you’re stung.

Most of the time, the pain and rash will go away in hours, or sometimes days.

Other symptoms after a sting can include nausea, vomiting, headaches, respiratory stress or shock, according to a previous news release.

The caterpillars are typically prevalent in San Antonio from March through December.

Spiny oak slug caterpillar (USDA Agricultural Research Service,

Are the caterpillars a problem in your area?

“You are more likely to encounter stinging caterpillars when they leave their host plant in search of a spot to pupate,” said Keck. “They aren’t aggressive and won’t come after you, but they can drop from trees.”

Texans statewide should be on the alert and keep an eye on trees and shrubs for caterpillar development, according to the news release.

Some common tree hosts are apple, basswood, cherry, dogwood, elm, maple, plum and oak, which is a favorite of the buck moth caterpillar. Some stinging caterpillars may even be found on crops such as corn, AgriLife specialists say.

AgriLife Extension specialist Mike Merchant said puss moth caterpillars can be controlled when they become abundant by spraying with a residual pesticide such as permethrin, cyfluthrin or similar sprays labeled for control of caterpillars on ornamental plants.

However, this will also kill all the non-stinging or “good” caterpillars, which are an important food source for songbirds, according to AgriLife experts.

“The best solution to dealing with stinging caterpillars may just be educating adults and children on what these caterpillars are, what they look like, and the importance of not touching them with bare hands,” Merchant said.

The experts at AgriLife Extension say you should just enjoy the inchworms and fuzzy caterpillars from afar.

“We want Texans to know what these caterpillars look like and the importance of not touching them with bare hands,” said Hurley. “Looks can be deceiving and the best way to stay safe is to not handle anything you aren’t familiar with.”

About the Author:

Mary Claire Patton has been a journalist with KSAT 12 since 2015. She has reported on several high-profile stories during her career at KSAT and specializes in trending news and things to do around Texas and San Antonio.