University of Kentucky Department of Entomology

Mystery Bug Answers

Mystery Picture #46

Mystery Picture #46

University of Florida
Entomology, used with
USDA Insect and
Plant Disease Slide Set
(Mystery Pictures)(Mystery Pictures)


The Paper Wasp constructs a paper-like nest out of chewed up wood fragments. Their nests are usually found under ledges or eaves and are shaped somewhat like an umbrella. They are not as aggressive as their close relatives, the yellowjacket and the hornet. For more information, and to see a drawing of a paper wasp nest, see EntFact 620 - Controlling Wasps, Hornets, and Yellowjackets.


This month's mystery is not concerned with the name of an insect but rather a process that is taking place in this picture. This critter will not have the chance to go through the two final stages of metamorphosis, the pupal and adult stage.

Why not?
This caterpillar has been parasitized by a tiny wasp that has laid eggs on its body. The larvae that hatch from the eggs burrow into the caterpillar's body where they feed and grow. This damages the caterpillar to the point where it will eventually die without ever becoming a moth.

What are the white structures on this caterpillar's body?
They are pupal cocoons inside which the immature wasps are becoming adults.

What is happening inside this caterpillar's body?
The wasp larvae are slowly consuming the caterpillar's tissues and organs.

Extra credit:

1) What type of caterpillar is this?
tomato hornworm

2) On what crop(s) is it commonly found?
tomatoes, eggplant, tobacco

3) What taxonomic group do the white objects belong to?
Order Hymenoptera (the wasp and bee group), Family Braconidae

4) How could this process be used for biological control of these caterpillars?
Tomato hornworms, especially in the last stages of being a caterpillar, are significant pests on tomatoes, tobacco, etc. One caterpillar can eat most of a tomato plant in a day. If they were parasitized and did not reach this stage, or if they did not live to reproduce and make more hornworms, the crops would be protected.

Appropriately timed releases of the Braconid wasps into the garden or field could be used as a biological control (as opposed to a pesticide control) to infest the caterpillars with wasp larvae which would kill the caterpillars.

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