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Cocoons of Parasitic Wasps on Field Crops


This page was adapted from the article, "Cocoons of Parasitic Wasps," which appeared in Crop & Pest Report on August 5, 2021.

Cocoons of Braconid parasitic wasp found south of Dunn Center
Photo Credit:
M. Schollmeyer, grower

You may find the cocoons (pictured) on your crops and wonder whether it is a friend or foe?  These cocoons have been observed on wheat/barley awns and on soybean leaves.

They are Braconid cocoons from ‘good’ beneficial insects or parasitic wasps in the insect family Braconidae. These tiny parasitic wasps (or parasitoids) lay multiple eggs within foliage-feeding caterpillars, such as armyworms or loopers. Eggs hatch into larvae, and they eat the insides of the caterpillar, thus killing it. Parasitism by the braconid wasps often causes the caterpillar to crawl to the tip of the plant, and it turns it into a zombie. Each mature larva of the wasp emerges and then spins a cocoon outside the caterpillar body.

Janet J. Knodel
Extension Entomologist