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Can anyone say what this poor fly is? Scathophaga stercoraria? and is the fungus Entomophthora muscae?

4.5.11 c10mm on riverside vegetation, Wiltshire, UK.

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We have a comparable thread here: http://www.dipter...d_id=38765.

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Many thanks Sundew. The link you gave does seem to show the very same thing: Scathophaga stercoraria infected with Entomopthora muscae, and that fly also ended up with its wings spread open. I'd come across photos of other infected S.s in this pose so was fairly sure I'd got it right. Maybe this posture (high up on an exposed plant) helps ensure dispersal of the fungal spores. Insect fungi can be very controlling for sure: I've come across ants in the tropics clamped to vegetation with their jaws in exposed positions a few feet off the ground, with macabre fruiting bodies sprouting from their heads, and it seems this kind of relationship had evolved by around 50m years ago http://www.guardian.co.uk/science/2010/aug/18/zombie-carpenter-ant-fungus . Nature can be nasty!

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When I was a child, my interest was attracted by dead flies sticking to a window pane with a cloud of white powder around them (the fungus spores). That was a quite frequent phenomenon. Later I watched infested flies, the last walk of which had led to a position high up on a grass leaf or stalk. This behaviour is apparently induced by the fungus. When I was going to photograph a killed Scatophaga with monstrous abdominal swelling a wasp came and grabbed the expected "easy prey". As the fly stuck to the stalk the wasp left with its head only but was surely contaminated with spores thereby. Now I wonder if the fungus might do harm also to a wasp, but I have no reliable information. Dou you know more?

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Very interesting! Like me, you've clearly been watching closely what insects get up to since a young age... I like to know what species I'm looking at, but have always been most intrigued by what they are doing, and so much of what insects do gets overlooked even by experts with less interest in behaviour. As for your wasp, I doubt it would have become infected from the little I know of E. muscae's host range: this is an excerpt from the wikipedia entry on it: As well as the housefly, Musca domestica, infection has been observed in adult flies in the families Calliphoridae, Culicidae Drosophilidae, Muscidae, Sarcophagidae, Scatophagidae, Syrphidae and Tachinidae.[2] That may not be the most definitive source, but the name of the fungus is maybe a clue that it has a limited host range. Some Hymenoptera (ants for sure) are also very resistant to fungal attack, maybe vital due to often subterranean habits. The wasp may have helped spread the spores, though... All part of the "Fungus Masterplan" - as shaped by what has worked over the aeons - maybe..

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I have seen this fungus on much species in different families. That families were Muscidae, Scathophagidae, Fanniidae, Empididae and Syrphidae. But from all, Scathophaga stercoraria seems to be the most vulnerable one. Also Bibio marci seems to be infected much times.

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Ok thanks for your input on this nielsyese. Wikipedia's host list needs extending! Maybe hanging around on cow pats isn't the healthiest lifestyle for S.s , or maybe they pick it up from other flies they've predated.