Stinging Caterpillars
Io moth larva, Automeris io (Fabricius), Saturniidae;
flannel moth caterpillar, Norape ovina (Sepp)
puss caterpillar, Megalopyge opercularis (J.E. Smith), Megalopygidae;
saddleback caterpillar, Sibine stimulea (Clemens), Linacodidae;
and other species, LEPIDOPTERA


Stinging caterpillars are the immature stages of several species of moths. They may possess short spines or be densely covered with long hairs. Some of the more common stinging species are described below.

The Io moth larva is pea-green and has greenish spines tipped with black. A reddish stripe edged with white extends down the entire length of the larva's abdomen. The Io moth caterpillar is about 60 mm long when fully grown.

One of the flannel moth caterpillars, sometimes known as the hackberry leaf slug, has a few long, plumose setae in its early instars. In later instars, the long setae are more noticeable and there is a short, heavy spine adjacent to each spiracle. This spotted caterpillar is about 24 mm long when fully grown.

The puss caterpillar is roughly pear-shaped and densely covered with hair-like setae. The long setae may be pale yellow, gray, reddish-brown or light brown. This larva is about 25 mm long when fully grown.

The saddleback is one of the more distinctive stinging caterpillars. Its short, stout green body has a white saddle-shaped spot with a bright, purplish-brown center. Its thoracic legs are very tiny and no prolegs are present. This caterpillar grows to about 25 mm long when fully grown.


Distribution -- The distribution of stinging caterpillars varies with species. However, most species are found throughout the U.S.

Hosts -- All stinging caterpillars are foliage-feeding insects. Trees, ornamentals, field crops, and fruits all support infestations of stinging caterpillars.

Damage -- Stinging caterpillars are covered with hair-like, fragile hollow spines filled with an urticating venom. When the spines are broken by contact, venom passes through the spines onto the skin of people who come in contact with them. Burning, pain, swelling, and/or prolonged itching may result. In some cases, local lesions may persist for several days.

Life History -- Because there are several species of stinging caterpillars, a specific life history cannot be given which would apply for all. In general, moths fly during the summer and lay eggs. Caterpillars hatch and grow as they feed for several weeks. The caterpillars then pupate and ultimately new moths emerge. These insects hibernate as eggs, prepupae, or pupae, depending on the species. In any case, the caterpillars usually occur only in summer.


These insects are usually uncommon and usually no control procedures are warranted. However, if particularly large populations develop, they can be treated with insecticides like other leaf-feeding caterpillars.