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PaperclipPerfector  1yr ago (text post)   3646 thread views

Small-Scale Question Sunday for June 25, 2023

Do you have a dumb question that you're kind of embarrassed to ask in the main thread? Is there something you're just not sure about?

This is your opportunity to ask questions. No question too simple or too silly.

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Why do mosquito bites itch?

Is it entirely accidental, as in, evolution only cared about whatever stuff mosquito inject acting as an effective anesthetic for the duration of the bite, not about what happens next? Or maybe it's beneficial for humans (makes us much more alert and aggressive towards further mosquitos) or maybe even individual mosquitos due to intra-species competition?

Mosquito bites transmit bacteria and such as well as mosquito saliva which triggers an intense and localized inflammation response. Same thing with ticks and other blood suckers.

These are substances that require some amount of time for the body to notice and react, which is why bites don't hurt immediately or even shortly after receiving them. The mosquito has already fed and gone by the time the bite starts swelling and itching.

O, tick bites are a great example because they do not itch pretty much at all (and don't swell at first either), while mosquito bites start itching within minutes. So it is possible to anesthetize the bite location without immediately causing an immune response: why don't mosquitos do that, do they simply not care (evolutionarily speaking) or maybe there's some non-obvious benefit to it?

Ticks will stay on your body for comparatively a much longer duration than mosquitoes. I don't see how there's any actual benefit from a mosquito having any kind of analgesic property when they'll finish sucking and fly off in seconds. The benefit to a tick is much more obvious.

Additionly, as someone in the American south and no stranger to "skeeters" and ticks, I don't know that I've ever had a mosquitoes bite become itchy as quickly as you describe.

Ticks will stay on your body for comparatively a much longer duration than mosquitoes. I don't see how there's any actual benefit from a mosquito having any kind of analgesic property when they'll finish sucking and fly off in seconds. The benefit to a tick is much more obvious.

I understand. To reiterate, my question was: do mosquito bites become itchy because the mosquito doesn't care what happens after it has fed, so whatever it injects is optimized for short term anesthetic and anticoagulant properties, which by default causes itchiness later? Or are mosquito bites especially itchy because there is in fact some benefit in that to mosquitos or humans?

To that I received several responses basically claiming that itchiness is inevitable, because scabs itch when healing, skin itches when pierced, an immune/inflammation reaction is produced in response to introduced bacteria and foreign proteins, and so on. However ticks provide an excellent counterexample: it turns that when it's important to pierce skin without causing neither pain nor follow-up itching for days, Nature finds ways to do so, despite all of the problems above.

So then back to my original question: if it is possible to be entirely non-itchy, are mosquitos itchy simply because they don't care, or are they especially itchy for some reason?

I don't know that I've ever had a mosquitoes bite become itchy as quickly as you describe.

Well, yes, maybe not in a couple of minutes (it can be hard to determine when the bite itself occurred), but in 10-15 minutes for sure, based on the interval between me entering a mosquito infested area and realizing that I've been bitten in a bunch of places.

While a tick/mosquito is hooked up to you, its anticoagulant is not spreading under your skin -- when it pulls out, a little bit spreads from the wound site causing swelling/irritation. Neither creature 'cares' about this, because they are gone by then.

It's an allergic reaction to what mosquitos inject. If you live in the same area all your life your body will adjust to the local mosquitos and you won't get the bumps and itching. Or at least it'll be much milder.

Google suggests this is just the normal response to anything irritating your skin, which is a crazy, self-sealing, flexible membrane that keeps most contaminants out. Scrapes and cuts, especially scabs, itch too.

Scrapes and cuts, especially scabs, itch too.

It's not comparable at all. A cut doesn't begin to itch until after several days, and don't itch at anywhere the intensity proportional to the affected area. Needle pricks don't itch at all and they are tens or hundreds of times larger by area than mosquito bites. So no, it's evidently a reaction to the anesthetic stuff they inject.

Mosquito bites, being very small injuries, begin to itch much faster than bigger ones because they heal faster?

From what I remember, mosquito saliva is in fact an anti-coagulant, not a anesthetic -- this doesn't quite answer why it would be itchy, but I wouldn't be surprised if it were something to do with the healing process.

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