Stinging caterpillars in our midst

When you think of caterpillars, you think of worm-like leaf-eaters that are generally harmless to humans.  Caterpillars may be hairless, fuzzy like a wooly bear or even tufted with hair – almost inviting you to touch them.  But there are “stinging” caterpillars in Florida that should not be touched.  To touch any of the four different kinds of stinging caterpillars found in Florida can become a painful experience.  Beware the Io moth caterpillar, the saddleback caterpillar, the puss caterpillar and the hag caterpillar.

Stinging caterpillars  have spines tipped with venom known as urticating spines.  Many people who touch these caterpillars experience itching or burning; others may have severe reactions that require medical attention.   Io moth caterpillars are brightly colored spiny larva.  These large (around two and one-half inches long) caterpillars are pale green with white and red stripes and seem to be the most common venomous caterpillar found in Charlotte County – I just saw three full-sized specimens last week.  Their spines are yellow with black tips that occur on fleshy bumps covering the body.  Io caterpillars may be found feeding on hibiscus, certain palms and Royal Poinciana, as well as a variety of other plants including wax myrtle.  The adult is a colorful and stunningly beautiful giant silk moth, yellow to orange in color, complete with eyespots on the hind wings..

In addition to the Io moth, Saddleback caterpillars also give clues that caution is required with  bright colors and bristly hairs.  This insect larva is brown with a green mid-section outlined in white.  A gap in the center of the back gives the entire pattern the appearance of a saddle.  The adult moth is small and drab and otherwise unremarkable.  Saddlebacks may be found on dozens of plants including  viburnum, Brazilian pepper, a variety of different palms, hollies, hibiscus and podocarpus.

Another strange venomous caterpillar is called the puss caterpillar which is also known as the southern flannel moth.  The adult orange moths are very fluffy and soft in appearance – the Persian cats of the moth world!  Up to one inch in length, the gray or brown caterpillars look like walking hair pieces totally covered in what appears to be soft hairs.  Scattered amongst the soft hairs are the urticating spines.  Severe pain can be the result of touching this caterpillar when the toxic spines break off in the skin.  The toxicity of the sting will tend to increase as the caterpillar grows – it is known as one of the most venomous caterpillars in the U.S.  Keep an eye out for them on oaks and elms. 

A final caterpillar to watch out for is the hag caterpillar.  These really look like trouble!  With curved and twisted projections covered with stinging hairs, hags speak volumes with their appearance  figuratively screaming, “DON’T TOUCH ME!”  While not as common as other stinging caterpillars, they may be found on various native and ornamental woody plants.

Many of these stinging caterpillars are plagued with natural enemies that keep them under control including parasitic wasps and flies.  If you are stung by these caterpillars, the literature suggests that placing common transparent tape over the affected area and striping off the irritating hairs that stick to the tape will help.  Applications of ice and a baking soda and water paste will help relieve the pain.  As mentioned earlier, if the person stung has allergies, asthma or allergic reactions, obtain medical help immediately.

For more information on all types of stinging creatures in our area, please call our Master Gardener volunteers on the Plant Lifeline on Mondays, Wednesdays and Fridays from 1 to 4 pm at 764-4340 for gardening help and insight into their role as an Extension volunteer.  Don't forget to visit our other County Plant Clinics in the area.  Please check this link for a complete list of site locations, dates and times - http://charlotte.ifas.ufl.edu/horticulture/Plant%20Clinics%20Schedule.pdf.

Resources: 

Short, D.E., Habeck, D.H. & Castner, J .L. (2013) Stinging and Venomous Caterpillars.  The University of Florida Extension Service. IFAS.

Hall,  D. W. (2014) Io Moth Automeris io (Fabricius) (Insecta: Lepidoptera: Saturniidae). The University of Florida Extension Service. IFAS.

Hall,  D. W. (2013) Puss Caterpillar (Larva), Southern Flannel Moth (Adult), Megalopyge opercularis (J. E. Smith 1797) (Insecta: Lepidoptera: Zygaenoidea: Megalopygidae). The University of Florida Extension Service. IFAS.

Christopher S. Bibbs and J. Howard Frank