Don’t pet these cute but poisonous caterpillars in the San Antonio area


As you walked through a park or trail, you might have noticed some pretty fuzzy beige colored caterpillars lying around. Don’t let their kindness fool you. The creatures have powerful thorns that release venom that can send you to the emergency room.

Molly Keck, senior integrated pest management program specialist for the Texas A&M AgriLife Extension Service, told MySA that the South Texas flannel, also known as the asp caterpillar, typically makes an appearance in the area between Halloween and Thanksgiving.

In late spring or early summer, adult moths emerge and lay several hundred eggs on preferred host trees. While asp caterpillars can be seen year round, Keck says the largest generation shows up during the fall and winter periods.

Asp caterpillars rarely cause serious damage to trees or plants, but they can pose a health hazard to curious children and adults. If stung, a severe, throbbing pain may develop immediately or within five minutes of contact.

The fluffy-looking asp are covered with hundreds of thorny needles which, when touched, can cause severe allergic reactions.

Courtesy of Matt Comerford / Rice University

“Depending on your allergy level, you can have different reactions, but at a minimum it’s quite painful,” says Keck. “You may not have a bad reaction or need to seek treatment. Some people may have anaphylaxis or hives.”

Symptoms can include headache, nausea, vomiting, lymphadenopathy, lymphadenitis, and sometimes shock or respiratory stress. The pain usually goes away in an hour and the spots go away in a day or two. However, Keck says to ask your doctor how to treat your bites.

Keck says aspics are generally abundant in areas such as shady trees, shrubs, and wooded areas around homes, schools, and parks. If you’re not in those areas a ton, Keck suggests ignoring the creatures as they can occasionally fall. However, if they are around the house and in places where children play, Keck recommends using pesticides labeled for trees or shrubs.

“It’s not something new that we’re seeing,” Keck says. “We see them year after year, but it’s only a few years that you’ll see more of them in your landscape and that doesn’t mean you’ve done something right or wrong. This is exactly what nature does. . They’re definitely there. Kids always love to touch him because they look fuzzy and cute, but they’re not, so don’t catch him. Don’t pick him up because you’ll definitely regret it. “


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