I often get emails from the public asking for help in identification of pests or because they may be curious about a particular "creepy crawlie" that is in the yard. Usually, identification without a photo is pretty difficult. Now that digital cameras have become commonplace, sending an image along with the e-mail makes positive identification much easier. Sometimes, I even get really nice photos, as seen below of the Megarhyssa wasps ovipositing (laying eggs) into the tree. These wasps are members of the very large family of parasitic wasps (actually, parasitoids is the better term) known as the Ichneumonidae in the Order Hymenoptera. Most of them parasitize insects in the larval stage, especially moth and butterfly caterpillars, beetle grubs, and so on. Megarhyssa wasps (there are several species in Michigan) are able to thread a 4-inch-long ovipositor into the wood of the dead tree, where they presumably are able to deposit an egg in the tunnel of the siricid wood wasp, Tremex columba. The wood wasps (family Siricidae) are also members of the Hymenoptera, but chew into standing dead trees. The Megarhyssa larvae then attach temsleves to the wood-wasp larvae and eventually eat them. They pupate and emerge the following year. Male Megahryssa wasps can detect an emerging virgin female and will crowd around the hole as she chews her way out, and even attempt to mate with her as she is emerging.
Photos taken by Jim Kane, Waterford, MI, June, 2003
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