Braconid Wasps Are Parasitoids of Butterfly and Moth Caterpillars

One of the greatest parasitoids, responsible for many moth and butterfly deaths, is the braconid wasp.

Braconid Wasp Cocoons On Tobacco Hornworm Caterpillar

Braconid Wasp Cocoons
On Tobacco Hornworm Caterpillar

Braconid Wasp Cocoons On Hornworm Caterpillar

Braconid Wasp Larvae and Cocoons
On Hornworm Caterpillar

Braconid Larvae and Cocoons Tobacco Hornworm Caterpillar

Braconid Larvae and Cocoons
Tobacco Hornworm Caterpillar

Braconid Larvae and Cocoons Tobacco Hornworm Caterpillar

Braconid Larvae and Cocoons
Tobacco Hornworm Caterpillar

Yellow-shouldered Oak Slug Attached Braconid Wasp Cocoons

Yellow-shouldered Oak Slug
Attached Braconid Wasp Cocoons

Spiny Oak Slug Attached Braconid Wasp Cocoons

Spiny Oak Slug Caterpillar
Attached Braconid Wasp Cocoons

Geometrid Moth Caterpillar Attached Braconid Wasp Cocoons

Geometrid Moth Caterpillar
Attached Braconid Wasp Cocoons

Stinging Saddleback Caterpillar Attached Braconid Wasp Cocoons

Stinging Saddleback Caterpillar
Attached Braconid Wasp Cocoons

Sphinx Moth on Grapevine Attached Braconid Cocoons

Sphinx Moth on Grapevine
Attached Braconid Cocoons

Duskywing Butterfly  Broconid Wasp Larvae Exiting

Duskywing Butterfly
Broconid Wasp Larvae Exiting

Duskywing Butterfly Protecting Broconid Wasp Cocoons

Duskywing Butterfly Protecting
Broconid Wasp Cocoons

Moth Caterpillar Protecting Braconid Wasp Cocoon Stack

Moth Caterpillar Protecting
Braconid Wasp Cocoon Stack

Braconid wasp from a Monarch caterpillar Photo by Kimberly Vicek

Braconid wasp from
a Monarch caterpillar
Photo by Kimberly Vicek

Young Viceroy Butterfly Caterpillar Protecting Braconid Wasp Cocoon

Young Viceroy Butterfly Caterpillar
Protecting Braconid Wasp Cocoon

Young Sleep Orange Caterpillar Protecting Braconid Wasp Cocoon

Young Sleep Orange Caterpillar
Protecting Braconid Wasp Cocoon

Dead Unicorn Moth Caterpillar Protected Braconid Wasp Cocoons

Dead Unicorn Moth Caterpillar
Protected Braconid Wasp Cocoons

Braconid Wasp Empty Cocoons

Braconid Wasp
Empty Cocoons

Dead Braconid Wasp

Dead Braconid Wasp

Ants Eating Braconid Wasps in Cocoons

Ants Eating
Braconid Wasps in Cocoons

This sight is one that most people recognize.

What most of us don’t realize is that these are not eggs. These are cocoons. We never see the eggs that begin this process.

Braconid wasps lay eggs in or on the caterpillar.

The eggs hatch and the young wasp larvae drink the blood/hemolymph as well as non-essential organs of the caterpillar while the caterpillar is still eating and growing.

As the caterpillar grows, so do the wasp larvae. The wasp larvae do not take as long to mature as the moth/butterfly caterpillar.

Before the caterpillar is ready to pupate, braconid wasp larvae will leave the caterpillar by eating holes in the caterpillar’s skin/cuticle. They work their way out of the body, to the outside of the caterpillar. At that point, the larvae immediately begin making their cocoons.

There are two basic types of braconid wasps that parasitize butterfly and moth caterpillars.

1) One type attaches its cocoons on the caterpillar itself.

2) The second creates ‘zombie caterpillars‘, having made a chemical change in the brain of the caterpillar, causing it to live the rest of its life protecting the wasp cocoons.

Depending upon which type of braconid wasp is emerging, the cocoons are made either on the caterpillar or by the caterpillar.

1) The braconid wasps that attach themselves, stay on the caterpillar. The make their cocoons attached to the caterpillar, at the holes where they emerged. The caterpillar continues to live for a few days, sometimes moving about a little, but not eating and growing. It is now dying.

2) The braconid wasps that cause caterpillars to protect the wasp’s cocoons will make their cocoons either jumbled and/or under the caterpillar. Some make a stack of cocoons, one on top of the other.

Some of these wasps have made chemical changes in the brains of the caterpillar that causes the caterpillar to cover the stack with its own silk after the wasp larvae have made their cocoons. The caterpillar then sits on top of the stack of cocoons and protects them, the best that they can, from anything that approaches the stack of cocoons. They strike at intruders with their heads or abdomens. The caterpillar never eats again. It continues to protect the wasp cocoons until it dies. (See the photo captioned, “Moth Caterpillar Protecting
Braconid Wasp Cocoon Stack”.)

On occasion, the caterpillar is linked to the cocoons with a bit of silk and hangs below the cocoon stack. (See the photo captioned, “Dead Unicorn Moth Caterpillar Protected Braconid Wasp Cocoons”.)

Some wasp larvae make a loose stack of cocoons and the caterpillar climbs on top of it and sits, protecting the cocoons, until it dies. Once again, these caterpillars no longer eat after the wasp larvae emerge. (See the photo captioned, “Duskywing Butterfly Protecting Braconid Wasp Cocoons”.)

As you walk along, you may see these tiny cocoons in the grass or on plants. (See photo captioned, “Braconid Wasp
Empty Cocoons”.) This is due to the fact that, after the caterpillar dies, it normally falls to the ground and isn’t noticed. The braconid wasp cocoons are attached to the item and do not fall, even after the wasps emerge from their cocoons.

If the wasps have emerged from their cocoons, the end of each cocoon has a hatch-type opening. (See photo captioned, “Braconid Wasp
Empty Cocoons”.)

There are predators for braconid wasps.

Ants will empty braconid wasp cocoons. (See photo captioned, “Ants Eating Braconid Wasps in Cocoons”.)

Another predator is a hyperparasitoid. There are species of chalcid wasps that parasitize braconid wasps, inside their cocoons. These wasps tend to exit from the side of a braconid wasp cocoon while braconid wasps emerge from the end of their cocoons.

Farmers and gardeners consider these to be beneficial insects.

They are responsible for the deaths of many Tomato Hornworm and Tobacco Hornworm caterpillars, enemies of tomato plants.

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