Illinois Natural History Survey - University of Illinois

Braconid Wasp Cocoon

Hymenoptera: Braconidae

• Braconids are small wasps, rarely over 1/2 inch long, usually dark-colored with 4 transparent wings. Identification by the amateur is often difficult. The external cocoons resemble insect eggs, but are made of silk.

Host Range 
• Braconids are diverse and parasitize many insects. Some attack the host internally, others feed from the outside of a host insect. Different species of braconids attack insect eggs, larvae, pupae, and adults.

Life Cycle 
• The braconid wasp shown here attacks the tomato hornworm. Female wasps inject eggs into the caterpillar’s body. The larvae that hatch from the eggs feed inside the caterpillar until they mature and eat their way out through the caterpillar’s skin. They spin the characteristic cocoons from which adult wasps later emerge.

Other Information 
• Leave parasitized caterpillars with cocoons alone so the wasps can emerge to attack more hornworms.

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