Mosquito with Mite Larvae

2010 June 26

“So naturalists observe a flea/ has smaller fleas that on him prey/ And these have smaller still to bite ’em/ And so proceed, ad infinitum” – Jonathan Swift

S_ spotted this mosquito in the house, and requested that I eliminate it. It then landed on the window screen, and I noticed something odd about it. So, I caught it, put it in the freezer to quickly kill it, and then after it was safely dead and immobilized started getting pictures. See those red bits sticking out to the side? That’s not normal.

Let’s roll her around to try a better view. Notice that the abdomen is a bit distended with something dark. This means it’s a female, and that she got a blood meal out of one of the mammals in the house. And also note the bright orange red spots:

They’re mites! Parasitic mites! Sucking her blood![1] The mites are stuck into her pretty good. Remember that I killed her by freezing, which means that the mites are also killed, and yet they didn’t let go. This implies that their mouthparts were probably attached quite solidly as they were snacking on her body fluids.

Let’s zoom in a bit. This is as much magnification as I can manage with the lenses at hand. The graph paper is 1 mm grid squares, so we can see that these mites are only a fraction of a millimeter. It is possible to see that they have legs.

I’m only counting six legs. Mites typically hatch out as larvae with six legs, and they grow two more for a total of eight when they mature, so these are evidently mite larvae.

These appear to be in the suborder Parasitengona, and given that they were on a mosquito, they are most likely the larvae of one of the aquatic types generally known as “water mites”. They are related to the Velvet mites that are commonly seen on land, and their lifecycle is reported to be “very complicated”. The basic lifestyle is that the larvae hatch from eggs in the water, and latch onto an appropriate host that they parasitize by sucking its body fluids. As they mature, they first become a free-swimming predatory nymph, and then become a free-swimming predatory adult.

The complications come in when one wonders what they were doing on an adult mosquito. The mite larvae will parasitize a lot of aquatic arthropods, many of which are the larvae of things that will be able to fly as adults. In this case, the mosquito wiggler was initially parasitized in the water. When it matured and molted to become a mosquito, the mites would have been shed along with the pupal skin. They probably quickly climbed from the shed skin onto the adult and latched on before her wings dried enough for her to fly away. They were then along for the ride as she flew off.

This is pretty risky for the mites, because they are depending on her eventually coming back to water so they can jump off and mature[2]. But, once she does, the mites are now in a new location, and ready to become mite nymphs which can now switch to eating the mosquito wigglers from her eggs outright[3]. This way, they not only get dispersed, but they get dispersed to a site that will be pre-stocked with their next meal. How convenient is that?

So, anyway, back to the mosquito, because I know you want to see more of her. Here’s the business end – the stylet that she drives into your skin to suck your blood. Unfortunately I don’t have enough magnification to show any details of the tip, but it is certainly sharp enough to slice a hole right through your skin.

The close-up of her face shows both the eyes, and the bulbs where the antennae attach. Her antennae are nothing fancy, but the males use theirs to find females and therefore tend to be a bit bushier.

So anyway, on the one hand I’m glad she’s dead because, with that blood meal in her, she was bound to lay eggs and make even more mosquitos pretty soon. On the other hand, the mites probably would have done in her eggs (and probably her as well), so probably she was doomed anyway. And, just consider how lucky we are that the things that bite us are so tiny relative to us. If we had parasites that were as large relative to us as these are relative to her, we’d have things the size of cats hanging off of us sucking our blood. Pleasant thought, eh?

[1] Sucking the blood OF A MOSQUITO! Oh, the cosmic justice of it all!

[2] If it were to turn out that they were on a male mosquito, then he’s not going back to the water at all, in which case the mites would be out of luck. Although, they might be able to jump ship onto any females that he may mate with, in which case they would be able to get back to water after all.

[3] While these mites don’t bite people directly, they are getting their food as a direct result of the blood that their female mosquito host had eaten. So, they could actually be considered to be sucking human blood, in an indirect, once-removed sort of way.

6 Responses
  1. Carole permalink
    June 26, 2010

    Fascinating post. Thank you for doing the research.

  2. June 27, 2010

    Great post. I just blogged about it!

  3. June 27, 2010

    If we don’t get up when requested to go downstairs for the midnight snack, some of us do have creatures the size of cats hanging off of us!

  4. June 28, 2010

    Thanks, Carole and AnneB. And KT, I at least hope that your creature doesn’t proceed to suck your blood if the midnight snack isn’t forthcoming . . .

  5. June 28, 2010

    thats incredibly interesting!!! never thought of a mite being on a mosquito… forwarded the post to my granddaughter who is fascinated by mosquitoes…

  6. Charles Patrick permalink
    May 23, 2014

    I found this image by searching with Google as I once remembered seeing these on mosquitoes back in 2002 here in Ontario. I had sent an email to a professor at Rutgers University who said that they were probably parasites of some sort. Thanks so much for the clarification. Very interesting.

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