The family Tabanidae derives its name from the latin word tabanus, meaning “horse fly.” I’ve noticed that observing which orders and families of insects take their latin names from actual latin or greek words for the insects (e.g. roaches, lice, ants) tends to give an idea of which insects have historically made the biggest nuisances of themselves. Chalk these biting flies up on that list.
I like horse flies because they turn the tables on entomologists. I have had several experiences wherein it was unclear just who was hunting whom. It generally winds up with me flailing wildly with my net while running in circles to try to stay out of reach of the fly. The lady fly is, after all, on the lookout for a tasty blood meal to grow her eggs with, a meal she will secure by slicing open a wound with scissor-like blades on her proboscis. She’s also way faster and more agile than me. It’s extremely disconcerting.
Horse and deer flies can be distinguished from other flies by their large eyes, their enlarged third antennal segment, and by the pair of “Y” shaped wing veins that enclose the wing tip. Male horse flies, which do not blood feed, generally have eyes that meet in the middle of the head, unlike the lady in the picture above, whose eyes are set apart.
As a side note, my backyard is suddenly full of stable flies, a house fly-like muscid fly which rabidly attacks my ankles when I venture outside. Ow. If I’m overcome with masochism I’ll even try to get pictures for y’all.