By Amy Gosling, MD

Stinging caterpillars do not sting like bees. yellow jackets, hornets and wasps.  Instead, stinging caterpillars bear specialized bristles, spines or horn-like projections. These structure as hollow and contain toxins from poison-gland cells to which they are joined. These are primarily defensive structures for protection of caterpillars from predators and other enemies.  The sting inflicted on humans is not from a deliberate attack by the caterpillar, but the result of contact, usually inadvertent, with toxin-bearing spines.

Reactions to contact vary and include; slight to intense nettling, stinging, itching or burning sensation; development of dermatitis, rash, lesions or pustules; inflammation, swelling, and numbness at or around the area of contact; fever, headache and nausea; and in some cases intense pain.  Red (blood colored) spots may appear at the site of the sting.  The type of reaction depends on the species of caterpillar, degree of contact, type of toxin and susceptibility of the individual.  Reactions my be especially severe for individuals with allergies or sensitive skin. Rarely and individual can experience shock or respiratory stress. 

First aid includes and ice pack to the site of the sting, and oral antihistamines such as Claritin, Zyrtec, Benadryl or Allegra to relieve the itching and burning sensations.  For caterpillars with stout spines, try carefully applying cellophane to the site, and then stripping it from the sting site. This helps to remove the irritating spines.

For allergic reactions, such as generalized itching or difficulty breathing, see a physician immediately.  Eye injures should aslo be referred to a specialist immediately.

Click here to see what Stinging Caterpillars look like!