Parasitized caterpillar? - Aleiodes

These...

are hornworms (sphinx moth caterpillars) that have been mummified by "mummy-wasps" (Aleiodes species). If you go to this page, there is a link to a PDF you can download that will tell you exactly which species. I think A. cameronii but I would check to make sure.

Actually, the horn is a normal part of the caterpillar (which has fallen off in the fourth image), and the exit hole is from the wasp. The fact that some (like the one above) have no exit hole, have retained the horn, and look less bloated, probably indicates something, but I'm not exactly sure what. The parasite may have been parasitized...?

Nice finds! There's a lot going on around that lake!

… Charley Eiseman, 22 January, 2009 - 9:02pm

Thanks!

That's really neat! Thanks for the help! I looked through the pdf you pointed me to, and the only two that showed sphinx caterpillars as hosts were A. ceratomiae and A. texanus, of which I felt it looked more like the former (a Waved Sphinx caterpillar).

Do you think, then, that that's what this is, also? Possibly A. geometrae?

… Seabrooke Leckie, 22 January, 2009 - 11:50pm

I agree

A. ceratomiae seems like the best match, but I'm not familiar enough with these to say for sure. Your linked photo definitely looks like the work of another Aleiodes, but maybe not A. geometrae--it doesn't have the transverse yellow bands, and although the text doesn't mention it, it looks like that species is typically only attached by its rear end, not along its whole underside.

These things puzzled me for a long time, and then I lucked out when I happened to ask Scott Shaw what they were--I knew he was a braconid wasp specialist, but had no idea he'd written a whole book about these mummies!

… Charley Eiseman, 23 January, 2009 - 12:41am

Pre mummified caterpillar.

Do you happen to know if that spikiness on the caterpillar is just the way that particular one is or is it a result of the parasitization? I've only seen a few species of sphynx moth caterpillar and they're all smooth, even the horn. Just curious!

… Natalie Hernandez, 23 January, 2009 - 11:06am

Not sure...

If you look at page 97 of the PDF I mentioned, the mummy of Ceratomia sonorensis from A. texanus seems to have a similar texture (at least on the horn), but that particular caterpillar wouldn't be found in Ontario... It's interesting that the one with the exit hole is perfectly smooth. It's possible that there's a fungus at work here.

… Charley Eiseman, 23 January, 2009 - 1:40pm

Yes I see it now.

It looks like the caterpillar belongs to the genus Ceratomia, but maybe it isn't C. sonorensis. I just did a google search and a lot of images of different Ceratomia resemble that. They're mostly green or brown though, so I wonder if the whiteness is a fungus.

… Natalie Hernandez, 23 January, 2009 - 1:49pm