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University of Minnesota Extension

Species guide - species detail

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Ephialtes macer (Ichneumonid parasitic wasp)


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Ephialtes macer is in the family Ichneumonidae. Ichneumonidae are parasitic wasps that use their long ovipositors to deposit eggs on, into, or near an insect host. It is a large family, with over 3300 described species in North America. Ephialtes macer was the most common Ichneumonid wasp in Bee Atlas blocks, and it was widespread in the eastern half of the state.


Ichneumonids are typically slender wasps with long ovipositors, sometimes up to twice as long as their body. They have long antennae with 16 or more antennal segments.

Nest Structure

Most Ichneumonids are solitary parasitoids whose larvae feed and develop on a single host, although some species' larvae are mobile and will feed on more than one host. Hosts include a wide range of insects in the orders Hymenoptera, Lepidoptera, Diptera, Coleoptera, Neuroptera, and Mecoptera, and spiders and spider egg sacs. Ephialtes macer parasitized resin wasps in the family Sphecidae in Bee Atlas blocks.

Hole Sizes

Ephialtes macer emerged from column 3 holes in Bee Atlas blocks, corresponding with the small resin collecting sphecid wasps that they parasitized.


No information at this time.

Activity Period

No information at this time.


Triplehorn, C.A and N.F. Johnson. 2005. Borror and DeLong's introduction to the study of insects, 7th ed. Thomson, Brooks/Cole, Australia. Thank you to John Luhman for identifying all of our Ichneumonid specimens.

Minnesota Record Map

These data are from the Minnesota Bee Atlas project.

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