Here are a few photographs of kleptoparasitic flies stealing hemolymph from a praying mantis dining on a pentatomid. They might be Milichiella arcuata or M. lacteipennis, types of jackal flies, but those are just guesses. Jackal flies (Milichiidae) and frit flies (Chloropidae) are commonly found on dead insects, but the volatiles released by dismembered true bugs are apparently especially attractive (see Zhang and Aldrich 2004). And if you search online for images of jackal flies, they also seem to be common on dead or dying honeybees, so presumably bees exude a volatile that is attractive to flies as well. I’d love to find an article that times the arrival of various kleptoparasitic flies at different types of insects … could use the assemblages to give approximate time of death, I’m sure, just like on CSI. I don’t watch CSI, so I’m guessing here as well.

If you want to know more about jackal flies, I highly recommend Irina Brake‘s “Milichiidae online“, and this post on Ted MacRae’s blog.