I spend a few days each week sitting in a meadow waiting for flies to bite me. Not by choice. The reason we are in the meadow is to measure plant thermoregulation with an infrared camera.
But the camera, once we set it up, requires very little attention. Every few hours we change the battery, and the rest of the time we sit there to make sure no one steals it or shoots it.
Sometimes we make other measurements, but otherwise there is very little to do but sit, and wait for the insects to come.
Some are friendly enough.
But others, like this snipe fly (Symphoromyia sp. [Rhagionidae]), are not. They swarm our bodies, sit on our datasheets, find our skin, then bite, and draw blood.
Every bite causes a painful swelling that lasts for hours and sometimes days.
They are surprisingly resistant to being crushed, often flying off after blows that would do in other insects. But they are slow, and most can be killed with a hand. Unfortunately, there seem to be an infinite population of them – no matter how many we kill, more kept coming.
I began wondering how many flies there really were. So I started a collection. Every time one landed on me, I tried to kill it. And then I put each of the victims into a plastic bag.
By the end of a 15-hour field day I had about a hundred dead flies in a bag. I estimate I was able to kill about a quarter of the ones I tried to hit, and probably ten landed on me for each one I aimed for. That corresponds to about 4000 flies. Far too many.
My fly collection was a small victory against the swelling and the itching, but it helped pass the time on these long days in the field. It made me wonder where all these flies went at night. I looked under all the nearby plants at sunrise and sunset, but didn’t find any flies. Some cursory searching suggests that very little is known about their life cycles – which is fascinating given how abundant they are for a few short weeks each year.
Not a research project I plan to pursue. I think it would be too painful. I’ll stick to collecting flies instead.