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Description and Biology

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Caliroa nyssae is one of the sawfly slug caterpillars that usually feed as skeletonizers on leaves. It could well be called the blackgum leafslug or the blackgum sawfly because black gum is the only host from which it has been reported. The adult of this caterpillar is an insect that resembles a fly more closely than a moth. Females are almost 3/16 inch long and black with white feet and lower legs. The translucent, smoky-brown wings are held flat over the back. Males are similar, but slightly smaller. Females have a sawlike ovipositor with which they pierce leaves to insert their eggs inside. Caliroa nyssae caterpillars are small, translucent, greenish, slimy caterpillars slightly wider at the head end. Sawfly slug caterpillars overwinter in the soil in a small cavity that is lined with the secretions of the caterpillar. They pupate the following year and the new adults emerge to mate and lay eggs. The caterpillars are sometimes abundant in early July. Caliroa nyssae may have two generations each year in North Carolina as the adults have been collected in August also.

Pear slugs caterpillars skeletonize leaves of their host plants.

Pear leafslugs closely resemble blackgum leafslug sawfly caterpillars.

Photo by J.R. Baker, NC State University

A pear slug caterpillar on its side to show its ten pairs of legs.

Caterpillars in the genus Caliroa have 10 pairs of legs.

Photo by J.R. Baker, NC State University

An adult pear slug.

Pear leafslug sawflies closely resemble those of Caliroa nyssae.

Photo by Whitney Cranshaw, Colorado State Univ.,

A side view of an adult pear slug.

The legs of Caliroa nyssae are paler than those of the pear leafslug sawfly.

Photo by Cheryl Moorehead,

Host Plant

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Black gum (tupelo) is the only host listed for this leafslug caterpillar. It can cause large portions of their host trees to brown out and drop leaves prematurely.

Residential Recommendations

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An abundance of Caliroa nyssae may cause alarm, Sevin insecticide or any other insecticide labeled for landscape use should give more than adequate control.

Other Resources

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For assistance with a specific problem, contact your local N.C. Cooperative Extension Center

The Factsheet has not been peer reviewed.


Professor Emeritus
Entomology & Plant Pathology

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Publication date: May 23, 2019
Revised: March 25, 2024

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