Crop & Pest Report

Accessibility


| Share

Mystery Insect (05/12/16)

This large worm (or larva) about 2 inches long was found tunneling into the heartwood of an old ash tree near Minot, ND.

Mystery Insect

This large worm (or larva) about 2 inches long was found tunneling into the heartwood of an old ash tree near Minot, ND. The homeowner was concerned that it was emerald ash borer; however, it is NOT an emerald ash borer larva. See NDSU Extension bulletin on E1634 Emerald ash borer. It was identified as a carpenterworm (or carpenter moth, Prionoxystus robiniae). They attack a variety of trees including ash, black locust, cottonwood, elm, oak and willow. Larvae feed on the sapwood and, as they mature, on the heartwood. Larval feeding injury creates large tunnels about ⅜–½ inch wide in the wood. Trees damaged by carpenterworms are more susceptible to limbs breaking during wind storms. They have a long life cycle of 3-4 years in ND. They attack only sick or old trees, so the best defense is keeping the tree healthy.

jan.1

jan.2

Janet J. Knodel

Extension Entomologist

This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144/accession 1013592] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

USDA logo

Creative Commons License
Feel free to use and share this content, but please do so under the conditions of our Creative Commons license and our Rules for Use. Thanks.