Strange fly deaths?

[Pigeon feather]

Can anyone shed some light on what is going on here, I have over the past couple of days noticed a certain species of fly on my hawthorn tree seemingly dead all in the same position with abdomen raised and wings drawn down I have also noticed the bands on the abdomen are swollen and white, I have taken a photo of one collected a few days ago but now the swollen white bands have gone and the fly still appears very much dead, the only thing I can think of is a parasite of some sort

[Matt Smith]

It is an entomopathic fungus - it infects flies and alters thier behaviour so they settle and die on an exposed surface so the fungal spores have a better chance of dispersal.

[Pigeon feather]

That's great matt many thanks, though I am slightly worried as I have been using flies to feed my praying mantis they haven't eaten a fungus infested one but there was one on the hawthorn leaves I put in their enclosure, you don't think it will affect them do you? it only seems to be this particular fly species that I find with the fungus, not the green and blue bottles etc.