The southern flannel moth caterpillar hides a series of venomous spines under its soft hairs. Image: M. Merchant
TEXAS - Texans are entering the time of year when one of the region’s most visually striking, yet venomous, insects is most abundant: the puss moth caterpillar, commonly known as the "asp."
What is an asp?
The puss moth caterpillar, which is the immature stage of the Southern flannel moth caterpillar, or Megalopyge opercularis, is typically seen more often in the fall, according to entomologists. While rarely a threat to trees, the caterpillar poses a significant health hazard to people, especially children, due to its painful sting.
When a puss moth caterpillar rubs or is pressed against the skin, venomous hairs stick into the skin, causing a severe burning sensation and rash.
Dig deeper:
The flannel moth is an insect group named for the flannel-like, hairy appearance of the adult moth.
The caterpillars themselves are teardrop-shaped and covered in long, silky hairs, making them resemble a soft tuft of cotton or fur. Their color varies from yellow or gray to reddish-brown.
The hairs covering the caterpillars conceal fine, venomous spines. When brushed against the skin, these spines inject venom, causing an immediate, intense, and throbbing pain that can spread to the armpit region if the sting is on the arm.
Beyond a severe burning sensation and rash, symptoms can include headaches, nausea, vomiting, swollen lymph nodes, and occasionally shock or respiratory distress. Pain usually lessens within an hour, and spots typically disappear within a day or so.
Other common stinging caterpillars in Texas include the Io moth, buck moth and saddleback moth caterpillars.
Adult moth of the Southern flannel moth, Megalopyge opercularis, Photo by Laura Bellmore.
What if I get stung by an asp?
What you can do:
For stings, officials recommend applying an ice pack to the affected area. Oral antihistamines can help relieve itching and burning.
- Removal: For caterpillars with stout spines, such as the Io or saddleback moth, carefully applying cellophane tape to the sting site and then stripping it off can help remove irritating spines.
- Medical Attention: For allergic reactions, such as generalized itching or difficulty breathing, immediate medical attention is necessary. For severe pain, physicians may administer stronger pain medication, as aspirin is reportedly not effective.
Stings from the southern flannel moth caterpillar
Where are asps found?
The caterpillars are often abundant and can infest shade trees and shrubbery in neighborhoods, schools, and parks, feeding on common trees like oaks, pecan, elm, and hackberry.
To control high numbers of the pests, residual pesticides like permethrin or cyfluthrin, labeled for use on ornamental plants, can be applied. However, for areas like school playgrounds, entomologists say the best defense is educating students and teachers on what the caterpillars are and the importance of not touching them with bare hands.
The Source: Information in this article is from Texas AgriLife Extension Service.