In all cases I saw where it appeared as if a fungus killed a fly, the body was swollen with fungus tissue. The fly stopped moving after it had found a place te settle, usually on the tip of a branch or top of stem, but never on a leaf. This specimen looks similar to dead flies I kept in a closed tube for too long and fungus started to develop.

Paul

http://www.diptera.info

As science fiction as it may seem, there are several fungi that parasitize and kill flies. Amazingly, they actually seem to invade a portion of the fly brain near the end of the Dipteran life that causes the fly to crawl up or out on the highest exposed areas where another fly of that species can see them. The bodies of the flies are bloated appearing and this draws males of the species down when they are fooled into thinking that these are female flies laden with eggs. The male fly attempts sex with the fungal corpse and spores are transferred to the new amorous males. The fungus only parasitizes and kills males of the fly species.