Jenschke: Beware of the stinging caterpillars

Lonnie Jenschke
Texas A&M Extension Service
Jenschke

Stinging caterpillar season has started!

“Spring foliage has brought on an abundance of caterpillars, a few of whom carry irritating or even venomous hairs,” said Janet Hurley, AgriLife Extension integrated pest management.

What stinging caterpillars look like

“A good rule of thumb is if a caterpillar looks ‘fuzzy’ — don’t touch it,” said Molly Keck, AgriLife Extension specialist in integrated pest management and entomologist.

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. Asps have spines attached to venom glands that can lead to a nasty sting, rash and other issues.

Caterpillar sting symptoms and treatment

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. Other people may not feel much discomfort, and a red rash may be the only telltale sign.

If the caterpillar is still on you, immediately brush it off if possible and then use tape to remove the spines that may still be in your skin.

Washing the area with soap and water and applying an ice pack to the sting may offer some relief, and an oral antihistamine may help to relieve itching. Over-the-counter insect sting and bite relief products can also help.

Other symptoms after a sting can include nausea, vomiting, headaches, respiratory stress or shock. Since reactions to the toxins from stinging caterpillars can vary, seek medical advice or treatment immediately or go to an emergency room if you are concerned. Experts also stressed that any contact with eyes or an allergic reaction to a sting requires immediate medical attention.

Stinging caterpillar habitat 

You are more likely to encounter stinging caterpillars when they leave their host plant in search of a spot to pupate, which is currently happening with many caterpillars.  Texans statewide need to be on the alert and keep an eye on trees and shrubs for caterpillar development, which typically occurs now into the fall.

Pest management

There isn’t much you can do about managing these caterpillars until they all pupate and go away. You don’t need to worry about harm to your garden however, as stinging caterpillars typically do not do enough feeding to harm plants.

If you have large populations of stinging caterpillars and decide you need to try to manage them, you can try Bacillus thuringiensisvar. kurstaki, BTK. However, this will also kill all the non-stinging or “good” caterpillars, which are an important food source for songbirds. You may also look for a pesticide with active ingredients such as spinosad or azadirachtin, which are naturally derived products.  

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.

Lonnie Jenschke is the County Extension Agent – Ag/NR for Erath County. Contact him at l-jenschke@tamu.edu