Parasitic Insects

Braconid Wasps, family Braconidae; Ichneumonid Wasps, family Ichneumonidae; Chalcid Wasps, family Chalcidae; Tachinid Flies, family Tachonidae

A parasitic insect lives in or on one host individual that may not die until the parasite completes development. Several species of parasites suppress abundance of sorghum insect pests, especially aphids and caterpillars.

Adult braconid wasps are small (usually less than 15 mm long) and stout-bodied. Biologies of braconids are similar to those of ichneumonids except many braconids pupate in silken cocoons on the outside of the body of the host and others spin silken cocoons apart from the host. Braconid wasps parasitize many insects, but most often aphids and larvae of moths, beetles, and flies. Bodies of parasitized aphids swell and harden into “mummies”. The adult wasp emerges through a circular hole it cuts in the aphid mummy’s skin.

One of the most common and important braconid parasites in sorghum is Lysiphlebus testaceipes (Cresson). This shiny, slender black wasp commonly is seen in aphid, especially greenbug, colonies. The aphid mummies are tan to gold.

The many species of ichneumonid wasps are distributed widely. Adult size and markings vary. Most are wasp-like, and females have long ovipositors, often longer than the body. Most of these wasps are internal parasites of immature stages of the host. The parasite may complete development in the stage of the host in which the egg is laid or in a later stage. Most groups of insects are parasitized by ichneumonids.

Chalcid wasps are metallic blue or green and small (2 mm). Many species live inside minute insects or eggs of scale insects, aphids, caterpillars, or flies.

Tachinid flies resemble large house flies, are bristly, and mottled gray, brown, or black. Adults feed on flowers. They glue eggs to a host insect or on foliage where the host insect may ingest the eggs. Larvae are deposited on or in the host insect. Larvae feed on the host before pupating. Adults emerge before or just after the host dies.

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