The Habitat of a Parasitic Wasp

What It Is

• Members of the order Hymenoptera, the largest parasitic wasps can measure up to 1 1/2 inches long at maturity and fall into three common categories that include Ichneumon wasps, Braconid wasps and Chalcid wasps. Most measure no more than 3/4 inch long and save their stinging abilities for incapacitating their host victims. The wasps are generally black or brown, hairless and slim, and they sport long antennae and two pairs of wings that are either transparent or opaque. The small size of some species, such as the Trichogramma wasp, enables them to prey on the tiniest destructive insects or their larvae.

Where It Lives

• Most parasitic wasps spend their early lives on or inside the body of the host insect. After a wasp emerges and matures, it continues the tradition of seeking out new hosts to keep the population going. During the winter months when it's not living on or inside the body of a garden pest, the parasitic wasp takes up residence in perennial plants. You can ensure the presence of the wasps in your garden by purchasing them at a garden center and placing them in the garden where they hatch and establish themselves.

What It Does

• Due to its small size, the parasitic wasp most often goes about its work undetected, but there is no mistaking its presence in the form of white cocoons that resemble grains of rice attached to the back of a tomato hornworm or other large destructive caterpillar. The wasps also attach themselves to other insects by boring holes into their bodies where they lay their eggs or feed, eventually consuming the host. Their victims of choice are often webworms, aphids, leaf rollers, tent caterpillars and armyworms. Other appealing host insects include cabbage worms, cutworms, cucumber beetles, cabbage loopers, potato beetles, gypsy moth caterpillars and corn borers, which all cause considerable damage to garden crops.

What It Likes

• Certain species of flowers and shrubs appeal particularly to parasitic wasps by providing them with food and a winter habitat. The National Gardening Association suggests including plants that produce shallow-faced flowers such as alyssum and any members of the daisy family to act as a source of nectar and pollen for the wasps. Other flowers that attract parasitic wasps include marigolds, cowpeas, cosmos and white clover, as well as herbs such as dill, lavender and rosemary. The association also recommends creating a source of water for the wasps, which can be in the form of a birdbath or a small water feature.