The four major stinging caterpillars occurring in Florida are the Puss Caterpillar, Saddleback Caterpillar, IO Moth Caterpillar and Hag Caterpillar. Some less common ones also occur in the state. These caterpillars do not possess stingers, but have spines (nettling hairs) that are connected to poison glands. Some people experience severe reaction to the poison released by the spines and require medical attention. Others experience only an itching or burning sensation.
Stinging caterpillar’s feed on many pants, but they seldom are present in large enough numbers to cause serious damage. Their stings, rather than feeding, pose the primary threat. That’s why it’s important to learn to recognize and avoid these cantankerous crawlers. My information on stinging caterpillars was provided by Extension Entomologist Dr. Don Short and Dr. D. E. Short of the University of Florida’s Institute of Food and Agricultural Sciences
The puss caterpillar is stout bodied, almost an inch long, and completely covered with gray to brown hairs. Under the soft hairs are stiff, poisonous spines. When touched, the spines break off in the skin, causing serve pain. The saddleback caterpillar has a more striking appearance. It’s brown, with a wide green band around the middle of the body. There’s a large brown spot in the middle of the green band, giving the appearance of a brown saddle on a green blanket. The saddleback may exceed and inch in length, and is stout bodied. The main poison spines are born on pairs of projections near the front and rear of the body. There’s a row of smaller stinging organs along each side.
The IO moth caterpillar is pale green, with yellow and reddish to maroon stripes along the sides. It often exceeds two inches in length, and is fairly stout bodied. The poisonous spines, which form rows of bands across the body, are usually yellow with black tips.
The light brown hag moth caterpillar has nine pairs of variable length protrusions along its body, from which poisonous spines extend. The protrusions are curved and twisted, giving the appearance of disheveled hair of a hag.
Most contact with stinging caterpillars occurs in the spring and summer. As might be expected, children, campers, and gardeners are most frequent victims. When playing or working outdoors in infested areas, it pays to wear a long-sleeved shirt, long pants, and gloves.
Reactions to caterpillars poison vary with an individual’s sensitivity. Itching, burning, swelling, and nausea may be experienced. In severe cases, fever, shock, and convulsions may occur. If a person has a history of hay fever, asthma, or allergy or if allergic symptoms develop a physician should be contacted immediate. In cases of milder reactions, a strip of adhesive tape should be placed on and pulled off the affected area repeatedly to remove the spines. Then, apply ice packs, followed by a paste of baking soda and water.
Since so few stinging caterpillars are normally found on plants around the home mechanical methods usually offer the easiest means of control. Just carefully remove and crush the caterpillars, or knock them into a pan of kerosene. If a pesticide is needed, Bacillus thuringiensis (Bt), Seven or Malathion may be used in accordance with label directions for caterpillar control.