Entomology and Plant Pathology, Oklahoma State University
127 Noble Research Center, Stillwater, OK74078
Vol. 12, No. 23
Jun 21, 2013
Attack of the Elm Sawfly!
Eric Rebek, Extension Entomologist
This summer, elm sawflies may be chewing their way through elm leaves near you. While not common in Oklahoma, Dr. Rick Grantham has responded to three reports of elm sawfly within the past week, all centered on the eastern side of the state. Sawflies aren’t true flies but are a specialized group of wasps. Sawfly larvae, sometimes referred to as caterpillars, closely resemble true caterpillars, the larvae of butterflies and moths. The simplest way to distinguish the two groups is to count the number of pairs of prolegs, fleshy appendages located on the abdomen that enable the larva to grip plant surfaces. True caterpillars always have five or less pairs of prolegs, while sawfly larvae always have six or more pairs (Fig. 1).
Fig 1. (A) True caterpillars have five or less pairs of prolegs and (B) sawfly larvae have six or more pairs. Images: (a) E. Bradford Walker, Vermont Department of Forests, Parks and Recreation, Bugwood.org, (b) Gerald J. Lenhard, Louisiana State University, Bugwood.org.
Description: Elm sawfly adults are small, stingless wasps. They do not appear to have the constricted waist of many stinging wasps. Adults are the largest North American sawfly, measuring ¾ to 1 inch long, and are dark blue with yellow antennae (Fig. 2). Females have four