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Aliases Parasitic Wasp

Parasitoids, aphid wasps, fairyflies

Physical Features

These partners in the fight against crime can be large, like Ichneumon wasps that parasitize treeboring beetles. Or they can be very small, like fairyflies that attack insect eggs and are about 1-2 millimeters long, the width of a dry spaghetti noodle, when fully grown! Adults will have two pairs of wings, a constricted abdomen, and a stinger. Almost all parasitic wasps are harmless and none attack humans.
Let’s just say they really get into their work. Immature stages of parasitic wasps usually live inside the host insect. Sometimes you may observe cocoons forming outside the criminal, or larvae poking through the captive’s body! This most often happens to caterpillars.

Beneficial Features

For every insect species out there, there is a parasitic wasp that’s got its number. Parasitoids are very specific in the types of criminals they apprehend. In fact, farmers use many of these wasps as security guards to control insect pests. Different parasitic wasps in the Lake Whatcom area are each on the lookout for aphids, caterpillars, flies, beetle grubs, leafhoppers, or you name it! Adult wasps find the criminal, sting it and deposit an egg. The egg hatches and, depending on the species, it starts to consume the host, first eating non-essential organs, and finishing the host off in a miserable death of being eaten inside out! Some parasitoids can produce 500 wasps from a single egg in a single host.


  • Since many of our beneficial parasitic wasps are very small, offer small flowers in your garden, such as carrots and other Umbel flowers. Adult wasps usually drink flower nectar to get the energy they need to fight crime.
  • Although they seem vicious and indestructible, parasitoids can be very sensitive to pesticides and take quite a while to become re-established in a landscape after a chemical application.

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For more information, contact Scarlet Tang or Todd Murray
WSU Cooperative Extension (360) 676-6736
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