On the day before yesterday, at the campus, I found a brown aphid that did not move at all. That was so-called a “mommy” of aphid. It is a dead aphid that is parasitized and killed by a parasitoid wasp. At the time when an aphid becomes a mommy, the inside wasp has pupated. The host species of this picture is Acyrthosiphon pisum, the most famous aphid species.
This picture shows a mommy, from which the parasite has already emerged. The parasite species may be Aphidus sp. (maybe…)
I’m having a photo of the moment when the wasp just lay an egg into an aphid. This photo was taken last year in UK, so that the host and parasite species should be different from above.
fascinating bugs 
mmm Said:
on July 4, 2008 at 12:12 am
Oh, poor aphids.
The upper one has only the cuticle left, after mummification and parasitoid (how can you tell it is Aphidius?) emergence.
The orange-and-black parasitoid looks cool!
polyphenism Said:
on July 4, 2008 at 12:28 am
You are right! I’m not sure whether the parasitoid is Aphidus or not. Some species in the family Aphidiidae, probably. Do you know how many genera (and species) are there in Aphidiidae?
mmm Said:
on July 4, 2008 at 1:33 pm
According to the following site
http://edis.ifas.ufl.edu/IN338
Aphidiidae consists of 60 genera and subgenera and more than 400 species from around the world.
Do you know how many aphid genera and species, compared to the diversity of Aphidiid parasitoids?
polyphenism Said:
on July 4, 2008 at 1:44 pm
Thanks for the great information.
According to wikipedia, about 4,000 species are known. So, one species may be able to parasitize some host aphid species, I guess…
mmm Said:
on July 5, 2008 at 12:14 am
Wow, that many! I agree—maybe most of aphid parasitoids can parasitize several species.