Bug FAQGreene's Giant Ichneumonid Wasp
Megarhyssa greenei · Order: Hymenoptera · Family: Ichneumonidae
Greene's giant ichneumonid wasp lives in the United States and Canada. It is a parasitoid that lays its egg on the larvae of the sawfly Tremex columba; the wasp larva eats the host, pupates under bark, and emerges a year later. It looks much like Megarhyssa macrurus but has a shorter ovipositor (just over body length) and lacks the dark facial striping of that species.
Source: Wikipedia
How to recognize it
It does not have the dark stripe on the face that Megarhyssa macrurus shows.
Source: Wikipedia
Size
Its ovipositor is only slightly longer than its body, unlike the related species whose ovipositor can be twice its length.
Source: Wikipedia
What it eats
The wasp is a parasitoid of the sawfly Tremex columba.
Source: Wikipedia
Life cycle
Females locate a sawfly larva, lay an egg near it, and the wasp larva consumes the host, then pupates under bark and emerges a year later.
Source: Wikipedia
Where it comes from
Its range includes the United States and Canada.
Source: Wikipedia
Lookalikes
It resembles Megarhyssa macrurus but can be told apart by its shorter ovipositor and less extensive dark wing markings.
Source: Wikipedia
Where it is found in the US
Recorded in 39 of 51 states and DC. Most records: Ohio, New York, Michigan, Virginia, Massachusetts, Pennsylvania, Vermont, Illinois.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in North America; native in United States. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
What does Greene's giant ichneumonid wasp eat?
It parasitizes the larvae of the sawfly Tremex columba.
Source: Wikipedia
Where is Greene's giant ichneumonid wasp found?
It occurs in the United States and Canada.
Source: Wikipedia
Same family (Ichneumonidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Megarhyssa_greenei
Look it up elsewhere: GBIF · iNaturalist · BugGuide · Wikipedia
Text written 2026-10-24 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-24.