Parasitoids kill and actually consume their prey. In nature parasites usually only weaken or sicken their hosts. They are the beneficial parasites, or more correctly, “parasitoids” of the garden. Today when someone mentions good bugs, most gardeners quickly point to dragonflies, green lacewings, preying mantids and lady beetles as brave defenders of the garden.īut in addition to these relatively large and showy predators, a whole class of helpful garden insects often are unnoticed, unappreciated, and (sometimes) abused. By the 18th century birds, ground beetles and lady beetles were recognized as important controllers of pests. As early as ninth century China, farmers were modifying their orchards to aid the transfer of predator ants for control of citrus pests. Predators of pest insects, in particular, have attracted admiring fans, especially farmers. Many insects in both natural settings and the urban landscape have long been recognized by humans as “beneficial”, as in benefiting man. But when talking about gardens, and parasitic wasps that attack pests, the word pairing makes good sense. The words “beneficial” and “parasite” are not normally heard together. They attack caterpillars and, sometimes, snails. Tachinid flies are another kind of parasitoid.
The holes in this scale insect were left behind by emerging parasitoid wasps. Ichneumon wasps were among the first parasitoids discovered. Some parasitoids, such as this bethylid wasp are egg parasitoids, small enough to grow up inside a single insect egg. These tiny braconid wasps do not completely consume their tomato hornworm host before spinning dozens of pupal cocoons over their victim. The ensign wasp lays its eggs in the egg cases of cockroaches.
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