/ Maggie Koerth-Baker / 12 pm Fri, Feb 1 2013
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  • How to tell whether a mosquito is male or female (without getting bitten)

    How to tell whether a mosquito is male or female (without getting bitten)

    The mosquito on the left is a male Aedes aegypti mosquito. The mosquito on the right is his female counterpart. Viva la difference— and the difference is in the antennae.

    The mosquito on the left is a male Aedes aegypti mosquito. The mosquito on the right is his female counterpart.

    Viva la difference — and the difference is in the antennae. Mosquito antennae are lined with fine hairs called antennal flagellum, and the density of the flagellum differs from one sex to another. Males have many, many more antennal flagellum, turning their antennae into a pair of bushy bottle brushes. Megan Fritz, a post-doctoral student in the North Carolina State University department of entomology described them to me as the mosquitoes' mustache. Even though mosquitoes are tiny, the males' flagellum are prominently noticeable to the naked eye. Fritz can tell which mosquitoes are boys and which are girls, on sight.

    Female Aedes aegypti do the biting. But they don't have nearly as many flagellum and, thus, their hearing is not nearly as finely tuned as that of male mosquitoes. That's because the men and the women are looking for different things.

    Female mosquitoes are on the lookout for victims to bite. Like the males, they eat sugar. At the NCSU mosquito breeding facility, Megan Fritz feeds both males and females on sugar water. But, without regular meals of blood, the females lose their ability to reproduce. No blood, no baby mosquitoes. Unsurprisingly, then, female mosquitoes have special sensory abilities that allow them to find and procure blood.

    Males, on the hand, are primarily interested in finding females. And that's where those thick flagellum come in. Turns out, the flagellum are integral to the mosquitoes' ability to hear. Specifically, all those flagellum help male mosquitoes hear the very, very, very quiet sounds of female mosquitoes buzzing around. Sound waves make the flagellum move. That movement is carried through the antenna to a special organ that helps the mosquitoes actually make sense of the motion. Called Johnston's organ, it can tell males how fast the wings of nearby mosquitoes are beating and it can help them distinguish male from female, and species from species.

    Further reading:

    The Mosquito Reference Manual
    • A research paper that explains how mosquitoes hear and how the antennal flagellum work
    • Another paper that describes several ways that male mosquitoes use their antennae to explore their world

    / / COMMENTS

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    1. Aren’t the gentleman mosquitoes the ones that are 100 times the size of the lady mosquitoes?

      1. I too grew up with everyone telling me that “those are male mosquitoes, they don’t bite,” but they’re actually Crane Flies. It is true they don’t bite

        1. I always knew them as Mosquito Hawks (which Wikipedia redirects to Crane Flies! Same thing many names). I had been told that they were good to have around, because they hunt mosquitoes but do not bite people. I’ve never been bit by one, but never seen them hunting mosquitoes, I wonder if that part is true. 

          1. As Ito says, adult craneflies don’t eat mosquitoes, and I’ve seen books that say some don’t eat at all and are just a short-lived dispersal stage like mayflies.

            However, cranefly larvae are aquatic predators and may eat mosquito larvae, so they could be good to have around anyway.

            1. Many cranefly larvae are turf pests; but whilst looking up the aquatic types, in response to your post, I found the delightful fact that all cranefly larvae (both terrestrial and aquatic) are called leatherjackets, which describes the ones I have in my lawn and garden very well.

      2.  Mosquitos come in many sizes, but generally speaking the males and females are roughly the same size.  At least to the human eye.

        Around here, we have small stripy salt-marsh skeeters that can bite through denim, and larger (about 2x) freshwater ones that can’t.  I forget the genera – culex and anopheles, maybe?

    2. Don’t think many people will first look closely at mosquitos sitting on them to identify if they are dangerous or not, because they are seen by many as just annoying and the possibility of a bite is there. The clap of the hand is there and is able to kill them with a pretty hight possibility to kill them before they bite. However first taking a closer looks makes the risk higher to get bitten if it is a female one, so don’t think many will bother.

      1. Male mosquitoes may not bite but they do make more biting mosquitoes.  Show our predators and parasites no quarter.

    3. A picnic on the beach wouldn’t be the same without them. Worse than having blood sucked out from under one’s tender epidermal regions by mosquitos, is having one or several of them nagging at one’s ears while sleeping…bzzzzz, bzzzzsowwwwzzz…..

    4. You can tell male and female moths apart by their antennae, too.

      The females have simple whip-like antennae, but males have antennae like bottle-brushes, which increases the surface area able to pick up the female’s pheromones.  There are a few exceptions to this, though; unusual species like the Black Witch (Ascalapha odorata, or mariposa de la muerte if you’re Mexican).

      The Black Witch is also very unusual (for a moth) in that it purposefully makes sounds, and this is generally advanced as an “explanation” for the lack of fuzz on the males’ antennae.

      Bugs are endlessly interesting!

      1. Indeed.  The Biologist raises Antheraea polyphemus & Hyalophora cecropia every year. “Here’s how to tell the difference.”  

        Bugs ARE pretty cool.

    5. Around Lake Okeechobee, where I grew up, the pioneers (and some of the old-timers) called make mosquitoes ‘chizzy-winks’ and were thankful they couldn’t bite.  Still, they were numerous enough to put out kerosene or oil lamps on catfishing boats.  I was there a few years back, and on the lake shore I saw a bunch of old milk cartons covered in them.  They looked furry.

    6. Bill Cosby used to have a routine where he explained that only male mosquitoes made a sound when flying, the females are perfectly quiet.

      “So if you wake up in the middle of the night and you hear a buzzing sound, just relax, and go back to sleep, there’s no need to worry.

      But if you don’t hear any buzzing…”

    Comments are closed.