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Caterpillar - Microplitis

Caterpillar - Microplitis
Chanhassen, Carver County, Minnesota, USA
May 27, 2007
Size: ~2cm
I found several of these caterpillars with the same structure on the back. Is this a parasitic wasp pupa? Any idea what kind? Can you ID the caterpillar? I do not know the host plant (not the on it's on).

Moved from Cocoons and parasitized caterpillars. In re-reading my notes I saw that Microplitis cocoons start out whitish like this one (they end up brown), which removed the lingering bit of uncertainty I had.

Moved (again)
I've done some digging, and I'm satisfied that this is a braconid (note that the previous move was to Ichneumonoidea, which includes both ichneumonids and braconids). I'm also pretty well convinced that the wasp belongs to the genus Microplitis (of the braconid subfamily Microgastrinae), but to be conservative (for now) I'm dumping it with all the other photos of caterpillars with braconid cocoons. I've found a few sources that describe species of Microplitis as having ribbed cocoons, and the one illustration I found very closely matches your cocoon. The species of which I found descriptions are parasitoids of noctuid caterpillars, which is encouraging, and also one is described as making a cocoon that is 5-6 mm long (as yours seems to be), which is unusually long for a braconid cocoon (almost all that I've seen are about 3 mm long).

I'm not sure how long this link will last (it's a Google book search), but the illustration is on page 121 of:
Quaintance, A. L. and C. T. Brues. The Cotton Bollworm. U.S. Department of Agriculture Bureau of Entomology Bulletin No. 50. Washington: Government Printing Office, 1905.

Thank you for this discussion, which helped me identify a nearly identical observation I made last month on iNaturalist.

This is excellent. Thanks

Moved from Cocoons--I had forgotten that there are no images there anymore.

I've followed v belov's suggestion because I agree, there don't seem to be any other options, but with the caveat that I have never seen a cocoon that remotely resembled this before. David, if you find another one of these, it would be fantastic if you could save it in a container and get a photo of whatever comes out.

I will likely have occasion over the next few months to get in touch with braconid & ichneumonid specialists, and if I do I will direct them to this photo to see what they make of it.

Thanks for the suggestion. I certainly will collect if I find one next year.


i'd suggest moving it to Ichneumonoidea page

Wagner's Orthosia hibisci
looks rather similar, page 418, but the one image on BugGuide is very different.

Thanks, It does look very much like it in Wagner's and I have seen many of the O. hibisci adults in the same area.

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