mosquito feeding on horsefly

[BobBruyn]

Hi, I'm new to this forum, so please excuse my newbieness.
Recently on a trip to Canada, my friend swatted a horsefly. As I was experimenting with macro photography he suggested I take a shot. The horsefly wasn't dead and was struggling quite a bit. As I was holding it to get the shot, a mosquito attacked it. Eventually settling in to stick it in just behind the head. I managed to get a few shots in. I was just curious if this was normal behavior. A mosquito feeding on another insect?

[kevinkk]

Great photography.
Bizarre. News to me, I thought mosquitos fed on red blood, which I don't think insects have. Perhaps something else is going on.