Subject: parasitoid wasp
Location: Cochise County, AZ
August 1, 2016 10:15 am
Hello! The bug in the picture seems like a parasitoid wasp and I wonder what kind it is and what it is doing on the cadaver of a rat. It looks like it’s stinging the rat but it shouldn’t be laying eggs on it, right? Maybe feeding on small flies on it? The photo was taken March 8th, 2015. Thank you for your help!
We are currently going back through requests sent in the past few weeks that we did not yet open, and we are awestruck at this image. We agree it is a Parasitoid Wasp and that the host is likely the immature stage of a fly or beetle that is attracted to carrion. We have not begun the research on this yet, but we did send your image to Eric Eaton to get his input as well. We are posting it as unidentified and are going to immediately begin to do some research. This is a very exciting posting for us and we hope to be able to identify the genus or species for you. This is the kind of posting that validates our practice of going back a few weeks out of guilt to look at all the requests we have left unanswered.
Upon doing a web search for “Braconid on Carrion” we found a Google Books online pdf from The Entomologist’s Monthly Magazine, Volume 43 that states: “Few Hymenoptera are found in carrion; the commonest is a Braconid, Alysia manducator, which is parasitic upon both the Dipterous and Coleopterous larvae (cf. Marshall, Bracon, d’Europ., ii.377); I first took it on a foal at Brockenhurst in May and subsequently on a rabbit in June, also on a horse’s shin bone and a cow’s head in the same month. An Ichneumonid, Atractodes bicolor, which may be hyperparasitic on the last species (cf. Morley, Ichn. Brit., i, 291 et ii) was taken in a rabbit in September, 1895, in a cow’s head at Lyndhurst in August and in a mole in June; its cousin, A. gilvipes, was once found in a rabbit early in June, 1903. A second kind of Braconid (? Rhogas sp.) was taken in the same kind of animal at the end of September, 1899; and a third, Meteorus filator, in a rabbit in November. ” All that is from an old English publication, but it does validate that there are Parasitoid Wasps that will search for hosts on carrion. We searched BugGuide for the genus Atractodes, and worked backwards to the subfamily Cryptinae, and BugGuide states: “Mostly external parasites of pupae and cocoons; a few attack wood-boring beetle larvae, others attack larvae of Diptera, a few are hyperparasites of braconids and other ichneumons.” We similarly searched Alysia on BugGuide and back to the Tribe Alysiini on BugGuide where it states: “Often in moist habitats and decaying substrates, where host larvae are likely to be found” and “Larvae are parasitoids that feed on larvae of cyclorrhaphous Diptera (advanced flies with short antennae).” We followed other links and did not find anything that looks like your Parasitoid Wasp, but we know we are on the right track.
Eric Eaton responds
Interesting. Definitely one of the colorful Braconidae, and she is certainly ovipositing on *something.*
author, Kaufman Field Guide to Insects of North America
Thank you so much for your reply! I’m so excited to hear from you. Your second email is very informative and answers my question why the wasp was on the carrion. This is the first time I posted my photo on any public website and I’m glad I did. Hope to hear from you with the species name and I really appreciate your time and effort.
Update from Kana: August 23, 2016
BugGuide had a photo of wasp very similar to mine and it was taken in my area: http://bugguide.net/node/view/464251
They filed it under subfamily Agathidinae. The only thing is that they say it hosts Lepidoptera larvae and it doesn’t explain why mine was on rat. But thank you for your help!
Hi again Kana,
The BugGuide information “hosts: Lepidoptera larvae” is so general it might not apply to all members of the subfamily. Some parasitic Hymenopterans are not well studied and many have mysterious life cycles. The BugGuide information might also be wrong. Thanks for the update.