About a week ago I got a voice message on my phone from a former Master Gardener who suggested I write a column on stinging caterpillars because she had been stung by one. She said the sting was very painful and she had to go to the hospital.
Just recently the son of my program assistant, Suzanne Holmes, was stung – but not directly. After he caught a caterpillar, he put it in a plastic container. When he opened the container to show the caterpillar to his mom, he set the lid on his arm. A few minutes later his arm turned red and became swollen. He also got a little nauseated.
Most, if not all, of us who work in the yard much have had the unfortunate luck of being stung by one of these caterpillars at one time in our life.
Caterpillars are nothing but the larvae of insects: butterflies, skippers and moths. They fall in the Lepidoptera species and are the second-largest of all insect orders; consequently, caterpillars are very numerous. There are more than 11,000 species in North America, with more than 5,000 in the eastern United States.
Caterpillars come in a variety of shapes, colors and sizes. Some species are bare while others are sparsely to densely clothed with fine hairs. Some are drab, while others are brightly colored. Some have smooth bodies, while others bear bristles, spines and/or hornlike projections. Within the group are found some of the largest and most striking representatives of our native insects. Most caterpillars are not poisonous, but there are a few that sting.
CATERPILLARS DO NOT sting in the manner of bees, yellow jackets, hornets and wasps. In those groups, females are equipped with venom glands and stingers with which they penetrate the skin and introduce the venom. In contrast, stinging caterpillars have pointed spines for defense against predators. The sting inflicted on humans is not from a deliberate attack but the result of contact, usually inadvertent, with the toxin-bearing spines. When brushed against or touched, these structures break away, releasing toxins. In some cases, broken spines might penetrate the skin; in others, toxins spill out to spread on the surface of the skin.
Reactions to contact vary and include slight to intense irritation, stinging, itching, or burning sensations; development of dermatitis, rash lesions or pustules; inflammation, swelling and numbness at or around the area of contact; fever and nausea; and in some cases, intense pain. The type of reaction depends on the species of caterpillar, the degree of contact, type of toxin and susceptibility of the individual. Fortunately, most of these caterpillars live and feed high up in trees, but when the wind blows a lot or when trees fall down, so do the caterpillars.
THERE ARE A NUMBER of these caterpillars in our area. Some to look out for are the saddleback caterpillar, hag moth caterpillar, puss caterpillar and slug caterpillar.
The most common one is the saddleback caterpillar. More people come in contact with this one because the caterpillars feed on numerous trees, shrubs and flowers. Their food sources are plants that we come in contact with every day such as canna lilies, azaleas and fruit trees. Fortunately for us, the moths lay single eggs.
The caterpillar is brown with a pronounced green saddle-shaped area over the center of the body. The spines are colorful and sharp and protrude from the front, back and sides of the caterpillar. The spines are connected to poison gland cells.
The stings from these caterpillars are very painful. I can attest to this. As a young, inexperienced county agent in Stephens County in 1982, I had only been working a couple of months when someone brought one into my office for identification. I made the mistake of touching it, so it left a lasting impression!
A strange-looking stinging caterpillar is the hag moth larva. It is brownish with four pairs of long, plume-like projections on the back, suggesting the disarranged hairs of a hag. Among the brown hairs on the plumes are larger black stinging hairs. The hag moth can be found on many of our trees and shrubs, such as sassafras, spirea and wild rose.
Another species with stinging hairs is the puss caterpillar. This is a very common species in the South. It mainly feeds on leaves of oak, hackberry, elm and sycamore. The caterpillars are densely covered in long hairs that might be yellowish, reddish brown or mouse gray. The young larvae typically feed in groups. They will eat all of the leaf material between the veins, leaving a leaf skeleton behind. In our area, there are two generations per year.
The last of the stinging caterpillars I will mention is the slug caterpillar. Some of these, such as hackberry leaf slug, actually look like a caterpillar. The hackberry leaf slugs feeds on redbud, red maple and hackberry. They have six small tufts of stinging hairs on each segment. The other slug caterpillars, such as the skiff moth, do not look like caterpillars at all – they are shaped like triangles. These triangles have short spines along the edges.
YOU CAN SOMEWHAT protect yourself against all these stinging caterpillars by wearing long-sleeved shirts and gloves while working in the yard. You can also reduce your exposure by not brushing up against the leaves of plants. If you come in contact with one of these caterpillars, you can remove spines with adhesive tape.
As mentioned before, the poison can cause burning, itching and even nausea for several hours.
By the way, the caterpillar that stung Suzanne’s son was the bright yellow spotted apatelodes caterpillar.
REACH SID MULLIS, THE DIRECTOR OF THE UNIVERSITY OF GEORGIA EXTENSION SERVICE OFFICE FOR RICHMOND COUNTY, AT (706) 821-2349 OR SMULLIS@UGA.EDU.