Male midge – “mufflemouth”

2009 February 28

We found this little guy on the side of the house on May 14, 2008,[1] when it was still getting pretty cold at night. He’s an example of the ones that S_ refers to as “mufflemouths”[2], because of their big, muff-like antennae.

This looks to be a midge in the family Chironomidae. He’s certainly a male, because it is the males that have the huge, fluffy antennae. They evidently use them to track the scent of the females, who have much more “normal” antennae.

The antennae are a lot like the fluffier sorts of bird feathers, with a central rib and a lot of fuzz sticking out to the side.

The head is tucked quite a way under the thorax, and it was hard to get a picture of his face. This was complicated by a serious error on my part: it is a mistake to try to photograph a dark insect on a white background, particularly if you are letting the camera set the exposure automatically. The camera will control the exposure based on the white background, and the actual insect ends up underexposed. This next picture originally showed hardly any detail, I had to kick up the contrast outrageously just to be able to see anything at all, which is why it seems to be emerging from a clould of celestial light.

Anyway, from this picture, it looks like he doesn’t have too much in the way of mouthparts. In fact, he may not *have* any functioning mouthparts, he may be just a breeding machine. One thing that is very odd, is that he has two large, smooth bulges on his forehead between his compound eyes. I thought at first that they might be very large “ocelli”, or simple eyes, but that would be very weird, because it looks like most of the Diptera (true flies) don’t generally have ocelli when they are adults. Aren’t poorly-exposed photographs that show insufficient detail fun?

So, I went rummaging around for a better picture of a midge’s face, and eventually found one at The Chironomid Home Page. Here’s a link to the high-resolution version[3] (it’s a male Tanytarsus gracilentus, which is probably not the same species as the one I caught, but it’s pretty similar).

Looking at this, I’m inclined to think that the bulges are not actually eyes at all, they are probably either the muscles to control those huge antennae, or the mass of nerves needed to interpret the signals from them, or both. Although, S_ pointed out that, as far as the midge is concerned, the antennae probably do have a lot in common with eyes: they are likely to be highly directional, and might even have enough resolution to “image” the sources of smells. They might not so much “smell” smells like we do, as “see” smells. If each of the fibers on the antenna goes to a particular nerve receptor, there could be a “retina” that maps out the concentrations of the things he’s smelling as a function of location on the antenna. This would be completely unlike the way that we smell things.

Chironomid midges are harmless to humans, they don’t bite (unlike “biting midges”, which we will doubtless get into later). The larvae live in the mud of ponds and rivers, and both the larvae and adults are food for fish. It looks like the “bloodworms” that pet stores sell for feeding to aquarium fish are typically midge larvae[4], and trout are very fond of the emerging adults. So, these are another one of the insects that fly fishermen pay a lot of attention to. If you do a search for “chironomid” on Google, you’ll find an awful lot of fly-fishing sites. You’ll also find quite a few research sites devoted to them, because they are very good indicators of water quality: there are a lot of different species of midge, each of which can tolerate different levels of pollutants, oxygen levels, temperature, etc. So, by finding out what species are living in a body of water (or, which species are preserved in the mud from the past), you can find out a lot about the characteristics of the water over time.

[1] Incidentally, as of February 24, I have been posting bugs on the Internet for exactly two years. Whoohoo! This makes 105 individual posts, and just about as many individual kinds of arthropods. There is some doubling-up, sometimes the same species will have separate pages for the larva and for the adult, so it’s pretty close to 100 species.

[2] She says her father always called them that. It’s a good common name, even people who aren’t familiar with it are likely to understand right away which insects it refers to. Funny thing, though: a Google search didn’t turn up “mufflemouth” in connection with midges. Well, it will now!

[3] I thought about actually directly displaying the image on this page, rather than just giving a link that you can click. But, I’m not so sure about the copyright issues, and even though everyone *else* seems to freely display images that they link to, that doesn’t mean that it’s legal or anything. Based on this page, it sounds like actually displaying somebody else’s image on my page is only fully legal if I get permission first. And, since the Chironomid Home Page explicitly gave the copyright information for the image, I figured the least I could do was to not violate it.

[4] Not all bloodworms are midge larvae, though. There is a species of true worm that is also sold as “bloodworms” by pet stores, to feed to fish. These can actually reproduce in your aquarium, and if they get ahead of what the fish can eat, they can kind of take over the gravel of the aquarium. At least, that’s what happened to us when S_ got some “bloodworms”[5] to feed to her goldfish many years ago. The midge larvae, on the other hand, can’t reproduce without producing mature midges, so they can’t really breed out of control in an aquarium.

[5] They were probably actually Tubifex worms, or maybe Blackworms, and not really “bloodworms”

3 Responses
  1. March 3, 2009

    Another fantastic post. If you hadn’t told me the photography was bad, I wouldn’t have noticed save for one photo. I thought the resolution on the feathery sensors was great.

    As for the larvae, I think the Tubifex worms that I used to chop up and feed to my Neon Tetras were true worms.

  2. April 9, 2009

    This is such a cool website! I was googling information about carpet beetle larvae (I always find them on my floors!) and was getting more or less grossed out. Then I read your interesting explanation about the bugs and was fascinated! I forgot how much I used to love science as a kid…somewhere along the lines I became a squeamish, boring adult. Thanks for the science lessons!

  3. April 10, 2009

    Thanks! What you describe is pretty much exactly the result I hoped for from this site, I’m glad it’s working out that way.

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