Mosquitos on window screen

2012 January 21

On July 2, 2011, I was upstairs early in the morning in our home office, writing something for this very blog. It was kind of hot inside at the time, so I had the window over the desk open. After a bit I glanced out the window, and happened to notice these on the window screen:

They were, of course, mosquitoes, eagerly seeking my precious bodily fluids. They had picked up my scent through the window, and had come to feast, but were luckily stymied by the window screen. This, my friends, is why we invested in window screens[1], and why they are worth every penny.

Mosquitoes are the family Culicidae, but I’m not sure I can identify them much more definitely than that. These are pretty lousy pictures from an ID standpoint, because the screen blocks so many details (and most mosquito species look a lot alike in any case). These are all females, of course. The males don’t want your blood, and they mainly hang out elsewhere, mainly in the spots where the females will ultimately go to lay eggs. The females just want the protein and salts that are conveniently present in your blood. Like this one, giving me the eye through the screen mesh:

I think it helps one to appreciate how important protein and salts are to life when one thinks about the rather extreme risks that a mosquito is willing to go through to get them. Depending on who’s getting bitten, I suspect that upwards of half of the mosquitoes don’t survive the experience, being slapped, swatted, rubbed out, snapped at, or rolled on by their victims. And the survival ratio is probably even worse for biting humans, since we can wear clothing to limit the number of bite sites, and can consciously target them as they bite. And yet, they keep coming, so it is clearly worth it to them.

As one might guess, we’d really like to have somewhat fewer mosquitoes. The normal advice for reducing their numbers is to eliminate their breeding spots, which means getting rid of anything that contains standing, stagnant water. Unfortunately for us, the stagnant water that our mosquitoes breed in is a couple of acres of swamp just north of our house. This consists of a lot of tufts of grasses, cattails, and mint plants, shielding thousands of little pockets of water. This is fed by a couple of small springs in the hillside, and so stays wet all summer long. It’s paradise for mosquito larvae, because the little pools are discontinuous. There are obviously no fish, and even predatory aquatic insects can’t readily move from pool to pool in this sort of situation, so the mosquitoes have things pretty much their own way. We do spread Bacillus thuringiensis israelensis (BTI) granules periodically, but this is more to knock back the black flies in the little micro-creek that runs through the bog, and it is hard to get it into even a majority of the little stangnant water pockets where the mosquitoes breed. So, for our particular situation, any solution to the mosquito problem has to focus more on the adults.

One thing that works is our Mosquito Magnet mosquito trap. These work by slowly burning propane to make a warm, CO2-enriched plume that is scented with a chemical lure (there are a couple of possibilities, our mosquitoes seem to be most drawn to the Octenol lure). Mosquitoes are attracted by what they think is the CO2-enriched breath of a mammal, and when they get close, a vacuum system sucks them up into a net, where they quickly dry up and die. The downside is that these traps aren’t cheap: the most inexpensive model is over $300, it uses up a 20 lb tank of propane about every 3-4 weeks, the chemical lure packs cost about $8 apiece, and the catalytic combustor gets progressively more finicky to ignite every time you re-start it, to the point that it isn’t really even worthwhile to haul the thing out unless the mosquitoes are getting pretty bad.

Even at that price, I think the mosquito trap was worth it. When we first moved out here, the mosquitoes and blackflies were unbelievable. Thousands of them would attack the instant one stepped outside, and when we first put out the Mosquito Magnet the bag just kept filling, and filling, and filling, until we had enough dead mosquitoes to fill a two-liter bottle. The population of mosquitoes crashed after that, and has never really recovered -now when we set out the trap, it might only collect a few hundred mosquitoes all season. Oh sure, we still have a lot, but it’s nothing like what it used to be. I think that we opened up a niche for things that compete with mosquitoes for stagnant water pools, and now thanks to the periodic BTI distribution they just can’t regain their former dominance.

Still, I’d be happy to finally get rid of them entirely, and the black flies, too. Unfortunately, the black flies don’t get caught by the mosquito magnet[2], so I’d like a different approach if I want to catch black flies along with the mosquitoes.

The experience with the window screen does suggest some possibilities, though. One is just this: what is the perfect lure for eliminating mosquitoes that bite humans? Obviously, an actual human! They smelled me and came after me in spite of the mosquito magnet, which they had to fly past to get to me. So the question is, what is the best kind of trap to bait with a person?

One easy approach is just to use our windows as a trap. We have casement windows[3] that open outward, with the screens on the inside. So, when the screen gets covered with mosquitoes thirsting for my blood, I just close the window and trap them between the window and the screen. Then I go and get our hair dryer, put it on high, and dry them to death – it only takes a couple of minutes. When the hot air hits them, they just curl up and drop.

Another approach I’ve been considering is to modify a small screened house, using a suction system, electrified grids, or maybe just sticky flypaper to kill any insects that insisted on hanging around it. Then I could sit in my little booth in the yard and read, while all the mosquitoes and black flies were drawn to me and then speedily dispatched. At which point I would laugh, and laugh, and laugh. Mwahahahahaha!

And the beauty of this approach, is that I don’t have to worry about the mosquitoes and black flies becoming resistant to it. Consider: if I use pesticides, or non-human-baited traps, or even predators, the mosquitoes that survive will still have the same thirst for human blood that they always had. So, when they evolve to resist whatever is killing them (by tolerating the pesticide, or not being attracted to the lure, or having immunity to the disease, or by avoiding the predator) and build their numbers back up again, they will still be after me and my family.


If I am the bait, the only way they can become resistant to the trap, is to no longer be attracted to the bait. Which is me! I will be applying evolutionary pressure for them not to be attracted to me! So even if they evolve in such a way that they are no longer captured by the trap, it won’t matter, because they won’t want to bite me any more! And, quite frankly, if mosquitoes don’t want to bite me, then I have absolutely no beef with their existence, and we can all live together in peace and harmony!

[1] If it weren’t for the bugs, window screens would be counterproductive. They block about 20% of the light, they noticeably slow down the airflow when you open the windows to cool off the house, they blur the view of whatever you are looking at through the window, and they are a bit unsightly. But they do keep out 99% of the mosquitos, which makes all their faults forgiveable.

[2] The black flies are attracted to the mosquito magnet, but it doesn’t catch them because they are stronger fliers than mosquitoes, and so can just fly away from the suction head (which doesn’t actually draw that much air). Luckily, the black flies are much more localized in their breeding spots. They require running water, so hitting the flowing streamlets with BTI granules knocks back the black flies pretty well.

[3] Casement windows cost a bit more than sash windows, but they seal more tightly when closed because the window swings against a jamb and locks into place, rather than just sliding. They are therefore good if you want a house that seals up in the winter.

12 Responses
  1. January 21, 2012

    Thanks, I think, for this little bit of summer and making me feel less annoyed at the 4ยบ temps, because I’d rather have biting cold than biting insects.

    Also thanks for causing me to exercise my brain very, very hard trying to remember the title of the movie you obliquely referenced in fourth sentence.

    I could hear Peter Sellers saying “Now, Dmitri…”

    I could see Slim Pickins ridin’ da bomb.

    I could even remember the subtitle of the movie.

    But until I went to IMDB, I couldn’t remember the name of the movie. Gaaaaaaa.

    {And then our router went out and I had to reboot and … well, now, here we are, well into the morning.}

  2. January 21, 2012

    Yes, the choice between freezing and being eaten alive by bugs can be a hard one.

    And I do have something of a tendency to quote Dr. Strangelove. Great movie.

    “Gentlemen! You can’t fight in here! This is the War Room!”

  3. JennyW permalink
    January 22, 2012

    When my husband was living in Belgium for 8 months, his windows had no screens. He had to pull the sheet over his head to prevent being eaten by mosquitos. I don’t understand why they didn’t have screens!

  4. Bridget permalink
    January 23, 2012

    I know they’re irritating (in more ways than one), but they’re also beautiful.

  5. January 23, 2012

    Bridget: True. They are elegantly adapted to do what they do. I still would just as soon eliminate them from our property as much as possible, provided it can be done with out disrupting everything else.

  6. January 25, 2012

    Re: The population crash. I once had a severe problem with snails in our garden. I tried all kinds of things – beer traps, granules, etc. I finally just went out at night with a flashlight and smashed them with my feet. The population dropped exponentially. After the fourth night in row of doing this, you couldn’t find more than a couple of them. I suppose they came back in numbers, but they ceased to be a difficulty.

  7. Fred permalink
    February 2, 2012
    Who says lasers aren’t lethal?
    Ok, maybe it isn’t the most economical but just imagine sitting on a chair luring the little flies to their smokey demise.

  8. February 3, 2012

    I actually met one of the guys responsible for the mosquito-shooting laser, and he admitted that that was the real reason for the project: while there are certainly cheaper ways of killing them, it’s really hard to come up with anything cooler.

    One just has to be careful to design it so that it will avoid actually shooting when there is a human body part behind the mosquito.

  9. (Somebody who really hates Ticks/Mosquitoes) permalink
    August 5, 2013

    What do you hate more Tim Eisele Ticks or Mosquitoes???

    I think I personally hate Mosquitoes slightly more since they are harder to avoid but I think Mosquitoes contribute atleast a tiny amount to the general ecosystem…Ticks are the most worthless animals ever and I’m pretty sure nothing eats them.

    Mosquitoes should be reduce….Ticks should just be eliminated…

  10. August 6, 2013

    The blood-sucking species of mosquitoes aren’t very important to the ecosystem, because there are so many non-bloodsucking mosquitos, midges and other small flies that fill the same niche. If every blood-sucking mosquito in the world dropped dead today, there’s really nothing that would miss them, except for the disease organisms that depend on them to be their vectors. And nobody is going to have much sympathy for the hardships of malaria or west nile virus.

    There are actually a fair number of things that eat ticks (small birds, reptiles, ants, parasitic wasps, and the other usual suspects), but on the whole I expect that if all ticks vanished, they wouldn’t be seriously missed by anything other than the diseases that they transmit, either.

  11. Darn you Ticks and Mosquitoes!!! permalink
    August 6, 2013

    Alright I changed my name (sorry if I was alittle emotional Tim but I had found 3 ticks on my head an hour before that comment)

    What type of reptiles eat Ticks??? I know some birds do (but Ticks also feed on/parasitize birds all the time so the eating is mutual) but from my experience Ticks parasitize reptiles and thats all there is to it. Snakes/Lizards/Turtles/even Crocodiles are parasitized by Ticks

    For example here is a typical interaction between ticks and a snake. As you can see the Ticks (unfortunately) came out on top in this one.

  12. August 7, 2013

    The reptiles that eat ticks are the smaller ones, like small insectivorous lizards. The eating is, as you say, mutual. The big snakes like the python you showed would have a harder time getting at the comparatively tiny ticks, but the closer in size a reptile is to a tick, the more likely the reptile is to eat than to be eaten.

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