Spiny Oak Slug Caterpillar (Euclea delphinii)
Family Limacodidae, order Lepidoptera

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Dorsal View -- Photo by Scott Gordon, Montomergy Co.

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Ventral View -- Photo by Scott Gordon, Montomergy Co.

There are about 30 species of slug caterpillars in the eastern half of the US. The Limacodids vary in morphology -- a few are smooth and rounded (slug-like), while others posses various spines, tubercles, or warts. Their heads are usually hidden, and their thoracic legs are reduced in size. The slug caterpillars do not posses prolegs similar to most caterpillars. Instead, they make use of ‘suckers’, of which there is one centrally-located in each of the first eight abdominal segments. The presence of these abdominal suckers is unique to this family and one other family of caterpillars. The slug caterpillars move in a wave-like motion and can leave behind a sticky, semifluid silky substance.

Limacodid caterpillars have an amazing array of colors and forms. Their spines cause dermatosis or irritation of varying intensity, so handling is not recommended. They have urticating hairs, which can embed in skin. Besides the mechanical action of the urticating hairs, many setae also have a poison gland associated with them, so that a toxin is released into the perpetrator’s skin when the tip of the spine breaks.

Limacodids pupate in cocoons and emerge as moths. The stout-bodied moths are frequently woolly in appearance. Many of the moths have distinct patterns on their forewings, and some males even have clear wings.

The photos above were submitted by county agent Scott Gordon. The spiny oak-slug caterpillar is pictured. These caterpillars can range in color from pink, orange, red, yellow, green, or tan. They can grow up to 2 cm in length. As can be seen from the photo, the sides of the abdomen have rounded depressions edged in black or white. The anterior and posterior ends have elongated spiny lobes. Spiny oak-slug caterpillars can eat a wide variety of deciduous plants, and frequently eat the tough, older leaves. Their sting is reportedly considered mild as compared to some other slug caterpillars.

Information obtained from:

Epstein, ME. 1996. Revision and phylogeny of the Limacodid-group families; with evolutionary studies on slug caterpillars (Lepidoptera: Zygaenoidea). Smithsonian Contributions to Zoology, number 582

Heppner, JB. 1995. Urticating caterpillars in Florida: 2. Slug caterpillars (Lepidoptera: Limacodidae). FL Dept. of Agriculture and Consumer Services, Div. of Plant Industry, Ent. Circular 372: 4 pg.

Wagner, D.L. 2005. Caterpillars of Eastern North America. Princeton University Press, Princeton. 512 pg.

September, 2007 -- Elizabeth Murray, Extension Entomology Diagnostician, gotbugs@ksu.edu .