Swarming “Ghost” Midge

2011 August 13

So, I was bicycling home on May 21, 2011 when I suddenly caught a swarm of these little guys in the face. I tagged this as “Found in Teeth” because I had to spit out two or three of them afterwards, but those weren’t in any shape to photograph. I caught this one by going back to the swarm (which quickly reformed itself) and waving a small jar around until I snagged one.

He was a little guy, only maybe 3 or 4 millimeters long (smaller than the average mosquito) and pretty thin. He and a few hundred of his brothers had formed a swarm more or less the size of a person in the middle of the bike trail, right next to a bright-yellow post that I think they were using as a landmark. At the right lighting angle, it was possible to see the swarm as a vague, shimmering shape, or “ghost” [1]. I unfortunately didn’t have a camera along, so you’ll just have to take my word for it.

I know he is male both from his fluffy antennae, which he was using to sniff out females:

and from the claspers on the end of his abdomen, which he would have used to hang onto her once he found her.

While he looks kind of like a mosquito, he isn’t one. He doesn’t bite, of course (male insects generally don’t)[2], but the females of his species aren’t biters either. He’s one of the Chironomid midges, which are known for making “ghost” swarms that hover over particular spots in lawns (and are particularly visible in the morning and evening in direct sunlight, when the low angle of the sun makes it easy to position yourself to see the light reflecting off of them).

While they look like mosquitos, they don’t sound like them. In fact, I’ve never noticed that the ghost swarms make any particular noise at all, unlike the whine of a mosquito coming after one’s blood. If we look closely at the edges of his wings, you can see a fringing of fine hairs, which I think might act as mufflers so that he can fly silently.

This is another example of a “mufflemouth”, like a similar midge that I photographed in May of 2008. They both would most likely have aquatic larvae that are blood-red (“Bloodworms”) and live in stream sediments. I don’t think that they are the same species, though, if only because their big, fluffy antennae look different: the previous one had the hairs on his antennae pointing forward, making it look like a plume feather. This one, on the other hand, has the hairs pointing straight sideways, more like a feather duster. The University of Minnesota Chironomidae Research Group says that there are at least 305 species of Chironomid midges that occur in Minnesota (and therefore probably are also in northern Michigan), and that there may be more than 100 species in any randomly-selected stream, creek, or pond. So, overall I think I’d be more surprised if they were the same species.

It’s pretty hard for us humans to tell Chironomid species apart, both because they are very tiny, and because we can’t sense the key difference (scent) that the midges use to tell each other apart. I bet that if we had a sense of smell like the possibly 3-D scent imaging that these guys have, we’d probably think that they were as distinct as, say, butterflies.

[1] There is a popular series of trout-fishing flies called “ghost midges”, which I think are based specifically on the larvae or pupae of the midges that form these “ghost” swarms.

[2] I’ve probably mentioned this before, but the general rule of thumb is: if an insect stings you or bites you, it is probably female. If it makes noise, flashes, swarms, or otherwise makes itself conspicuous, it is probably male (or toxic. Or both). There are exceptions (both sexes of fleas and bedbugs bite, for example), but this is generally the way to bet.

2 Responses
  1. August 13, 2011

    Amazing photographs! It looks like the little dude held still for you.

  2. August 17, 2011

    I was actually using a trick that Alex Wild recommended for getting insects to hold still: put an opaque cover over them (like a jar lid) for a minute or so, and get the camera lined up and pre-focused on where you think the bug is. Then remove the cover, and start taking pictures as fast as you can until it wakes up and runs/flies off. I managed to get about a dozen pictures that way before the midge suddenly took off and disappeared.

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