Gallery of parasitoid wasps

Most of the tiny Aphelinid wasps are parasites of Hemiptera, the “true bugs.” A few Aphelinids, such as this one, are parasites of aphids.

Aphids that have been parasitized by this wasp turn black when they are “mummified” — feeding by the parasitoid larvae has depleted the aphids’ bodies.

Encarsia Formosa, the whitefly parasitoid, is a widely used insect for biocontrol.

Whitefly parasitized by Encarsia formosa turn black but remain attached to the leaf underside. A high ratio of “mummies” in a pest population indicates parasitic wasps are providing some pest control.

Wasps of this subfamily of the Braconidae are parasitoids that specialize in aphids. While too expensive to be cost-effective in most home garden situations, several members of this group are commonly used as pest control agents in greenhouses and other controlled environments.

They also occur naturally across the world, wherever aphids are found. Aphids parasitized by this group of wasps may continue to eat, live and develop for a period while the wasp larvae grows inside its body, before becoming a tan or golden — colored “mummy.”

The wasp’s exit hole is often visible on the aphid mummy, indicating that aphid control is underway.

This huge wasp family includes parasites of moths, beetles and flies.

Depending on the species, the female wasp may lay eggs in the eggs, larvae, or pupae of the host insect. Some members of this wasp family exit the host body to pupate, and may pupate in silken cocoons on or near the host insect.

Most widely recognized are parasitoids of the hornworms.

Other members pupate inside the host.

Some of the 2,000 species of Chalcid wasps are parasites of scale, a common garden pest of woody plants. Other species of Chalcids parasitize insects we consider beneficial — such as mason bee cocoons.

Chalcids may also parasitize fly or moth larvae and pupae. Many Chalcids are just a millimeter or two in length, making them difficult to identify in the garden.

Chalcids that are large enough to observe with the naked eye might be recognized for their shiny, sometimes metallic-looking bodies, and greatly enlarged segments of the hind legs.

This family of tiny wasps, usually 2 millimeters or less in length, includes parasites of some of our most common garden pests — aphids, scale, mealybugs and whiteflies. Encrytid wasps are considered important naturally occurring biocontrols for these common garden pests. A few species are available for purchase, including Anagyrus pseudococci, a predator of mealybugs sometimes recommended for home grow rooms and greenhouses.

Anagyrus kamali is native to south Asia but is found all over the world due to its use as a biocontrol for mealybug.

Oobius agrili, a parasite of the invasive emerald ash borer, is pictured here depositing an egg into an emerald ash borer egg.

An unusual characteristic of this wasp group is called polyembryony: As many as ten to 1,000 wasp larvae may develop from a single egg.

About 600 species of Eulophid wasps have been identified in the U.S. Adult females may lay eggs in plant tissue with pest larvae inside (above), into beetle larvae or into other insects.

An eulophid wasp lays an egg inside an insect.

Biology and life cycle vary widely in this group. Adults are usually 1–2 millimeters and often have a metallic sheen, such as these emerging from a sawfly pupa.

Eulophids most beneficial in the home garden parasitize thrips, mites, scales and other wasps.

Some species parasitize psyllids, evident when the psyllid bodies are flipped over and the wasp larvae is visible.

Ichnuemonids, one of the largest of all insect families, include some larger parasitic wasps that are easier to identify in the garden. Ichnuemonids have long, slender bodies and many-segmented antennae that may be half or more as long as the insect body.

Some species are specialists, including those that specialize in spider egg sacs. Others are generalists, with larvae able to fully develop on a variety of insect hosts.

Adult females lay eggs on or near the host insect, depending on species.

The largest Ichnuemonids in the U.S. are up to 40 millimeters long and parasitize hornworms and wood-boring beetle larvae. These wasps use an extra long ovipositor (egg laying appendage) to insert eggs inside wood tissue so that the resulting larvae can reach the wood-boring beetle larvae inside the tree.

Ranging in size from 1 to 8 millimeters, Pteromalids are typically a metallic black, blue or green. The parasitic members of this family lay eggs in fly, beetle and wasp eggs and larvae. A few species parasitize insects much larger than the Pteromalid wasp, like caterpillars (above).

Adults emerge from the larvae or pupae of the host insect (above). A few members of this family have larvae that prey on other insect eggs and larvae without parasitizing them.

Trichogrammatids are among the smallest of the parasitic wasps. Most are less than 1mm in length and parasitize various kinds of insect eggs (above). One genus of this family parasitizes thrips eggs and is only .18 millimeter in length. Because they are so small, these wasps are difficult to observe in the garden, though several species have been used successfully as biological control. Parasitized eggs often turn black.