Deer Fly

2012 February 4

This is a fly that tried to bite me on the back of the head on July 20, 2011. She was about a centimeter long. Yes, I killed her. I’m not even a little bit sorry.

She’s a pretty typical deer fly, subfamily Chrysopsinae, except for one thing: most deer flies seem to have these crazily-colored iridescent eyes, while this one’s eyes are dark and featureless:

The colorless eyes might be my fault, though. You see, I didn’t completely kill her when I swatted her, and I wanted to finish her off in a way that would not cause more damage to her body. So I put her in a jar and popped her in the freezer for a couple of days. And, the eye colors of these flies fade after death, so any crazy coloration her eyes might have started with, was lost. I might have been able to resuscitate the colors if I had put her in alcohol, but I didn’t know that at the time, and it is much too late for that now. In any case, if we ignore the eyes she looks quite a lot like a number of the yellow deer flies in the genus Chrysops.

I’m afraid I squashed her abdomen a bit, but it isn’t too gruesome, so here’s her underside:

The main difference between deer flies and horse flies is the deer flies are smaller. They both bite either horses or deer (or people, or dogs, or probably 3-toed sloths if any were available), the name is just to indicate that one is smaller and more delicate than the other[1].

Deer flies are more plentiful, too, and they really, really like to attack that spot on the back of a person’s head where the hair swirls around in a circle. Right where you can’t see them, and also where they have a clear shot at a little spot of exposed skin.

The classic solution is to wear a hat, and put a Deer Fly Patch on the back of the hat. These are patches of 2-sided tape. The deer flies land on it, and get stuck. It looks effective enough, but I think you need to be careful not to absent-mindedly reach up and scratch the back of your head while wearing one. Another approach is the Deer Fly Helmet: a blue hard-hat with something sticky smeared all over it. This example has at least a hundred deer flies stuck to it. So does the hat in this video. The second guy evidently used Tanglefoot as the sticky material, which obviously works. I understand that this approach works well for black flies, too, using vegetable oil spray as the sticky substance. I need to get some cheap blue hard-hats for me and the kids before black fly/deer fly season starts. And a jar of something appropriately sticky.

[1] Although technically a moose is a deer, and a moose is as big or bigger than any horse.

5 Responses
  1. Carole permalink
    February 4, 2012

    Oh, the neighbors are going to be talking about me. Binoculars, camera, and now a sticky blue hat to go with my morning walk.

  2. February 5, 2012

    Yep, me too. I’ve already got a blue “bump cap” (a light-duty hardhat that costs about $5 – most hardware stores are likely to have them, and you can get them from lots of places online, including Amazon). I’ll be giving this a whirl as soon as our biting fly season gets rolling around the middle of May.

  3. February 5, 2012

    I loved the video! I used it and linked back to you in a post that will show up later today.

    A population study would be interesting. Wear the blue hat each day for 10 minutes and track the number of flies you pick up. Over time, you’d expect the population to asymptotically approach some low level.

  4. February 6, 2012

    I liked that video, too. There’s another one, of a fellow with delusions of making an actual professional video, where instead of a blue hat and Tanglefoot, he uses spray-on adhesive and a blue mop-bucket. He looks pretty goofy with a bucket on his head (his teenage son, who was acting as his cameraman, breaks down laughing at him at one point).

    Overall, I think the hardhats are likely to work better than buckets.

  5. July 1, 2020

    What an enjoyable dissertation! I got bit by one recently and couldn’t believe how bad it stung! I slapped it, but am not sure if I connected. It was on the back of my wrist, and I had a big went from it. I ran for the house, applied ice, then Aloe Vera gel. It’s much better now. It drew blood, and took a piece of flesh out! (Monster!)

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