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Publication #SP107

Stinging and Venomous Caterpillars1

D.E. Short, D.H. Habeck and J.L. Castner2

This fact sheet is included in SP134: Pests in and around the Florida Home, which is available from the IFAS Extension Bookstore.


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 reactions to the poison released by the spines and require medical attention. Others experience only an itching or burning sensation.

First Aid

Place clear tape over the affected area and strip off repeatedly to remove spines. Apply ice packs to reduce the stinging sensation, and follow with a paste of baking soda and water. If the victim has a history of hay fever, asthma or allergy, or if allergic reactions develop, contact a physician immediately.

Saddleback Caterpillar

Figure 1. 

The saddleback caterpillar

[Click thumbnail to enlarge.]

This is a very unusual and striking insect. It is brown with a green back and flanks, on which there is a brown, oval, central area that usually is bordered with white. The brown spot looks like a saddle, and the green area looks like a saddle blanket; hence, the common name (Figure 1). It may exceed an inch in length and is stout-bodied. The primary nettling hairs are borne on the back of paired fleshy protuberances toward the front and hind ends of the body. There is also a row of smaller stinging organs on each side. This caterpillar feeds on many plants, including hibiscus and palms.

Puss Caterpillar

Figure 2. 

Puss caterpillar larva is convex and stout-bodied.

[Click thumbnail to enlarge.]

The larva is convex and stout-bodied, almost 1 inch long when mature, and completely covered with gray to brown hairs (Figure 2). Under the soft hairs are stiff spines that are attached to poison glands. When touched, these poisonous spines break off in the skin and cause severe pain. Puss caterpillars feed on a variety of broadleaf trees and shrubs, and are most often found on oaks and citrus. In Florida there are two generations a year, one in spring and the other in fall. Natural enemies keep these caterpillars at low numbers during most years, but they periodically become numerous.

Io Moth Caterpillar

Figure 3. 

Io moth caterpillar is a pale green.

[Click thumbnail to enlarge.]

This is a pale green caterpillar with yellow and red stripes (Figure 3). It often exceeds 2 inches in length and is fairly stout-bodied. The nettling organs are borne on fleshy tubercles, and the spines are usually yellow with black tips. They feed on a wide range of plants, but ixora and rose are their favorite hosts.

Hag Caterpillar

Figure 4. 

Hag caterpillar is light to dark brown.

[Click thumbnail to enlarge.]

This caterpillar is light to dark brown. It has nine pairs (sometimes fewer) of variable-length, lateral spines, which bear the stinging hairs. These spines are curved, twisted and likened by some to the disheveled hair of a hag, for which it is named. It is found on various forest trees and ornamental shrubs, but is not as common as the other stinging caterpillar species (Figure 4).

Buck Moth Caterpillar

Figure 5. 

Buck moth caterpillar is yellow-brown to purplish-black.

[Click thumbnail to enlarge.]

This is a large caterpillar, 1¾ inch to 2¼ inch long when mature. It is yellow-brown to purplish-black with many small white spots and a reddish head. It feeds on oak, willow, and other deciduous plants (Figure 5).

Spiny Oak-slug Caterpillar

Figure 6. 

Spiny oak-slug caterpillar, Euclea delphinii.

[Click thumbnail to enlarge.]

The caterpillar is pale green and about ¾ of an inch long when mature. Favorite food plants include oak, willow, and other deciduous plants (Figure 6).

Flannel Moth Caterpillar

Figure 7. 

Mature flannel moth caterpillar.

[Click thumbnail to enlarge.]

This caterpillar is about 1 inch long when mature. Stinging hairs are intermixed with soft hairs in diffuse tufts. Larvae are creamy white, turning dark as they mature (Figure 7). They feed on oak and various other shrubs and trees.



This publications was adapted from SP 107 Stinging and Venomous Caterpillars, an insect identification sheet which is available as part of a 43-sheet set from the UF/IFAS Extension Bookstore, UF/IFAS Extension. Date first printed January 1992. Revised October 2013. Please visit the EDIS website at


D.E. Short, professor; D.H. Habeck, professor; J.L. Castner, scientific photographer; Department of Entomology and Nematology, UF/IFAS Extension, Gainesville, 32611.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.