Why do insect bites itch even after the insect has gone away?
Helen - Thatís a very good question because I get bitten like anything when I go researching in the tropics. Itís all about what it leaves behind inside you. They actually pump saliva into you full of anti-coagulating compounds because they donít want your blood to clot while theyíre there trying to suck it up. They pump you full of anti-coagulants and leeches do the same. This is why you bleed a lot if youíve had a leech bite. Your body can have an auto-immune response to that which is why it can swell. You can get used to it if you have a few over a few days. Some people can get used to it like having shots against allergies.
Tracy asked the Naked Scientists: When insect or spiders bite us, why does it itch? They bite us and then go away, what's in it for them that we itch after they're gone? What do you think? Tracy, Sat, 7th Jun 2008
The insect injects chemicals, such as numbing agents and anti-coagulants injected by mosquitoes, when they bite. These chemicals cause the human body to produce histamine and the itching of this histamine reaction is part of the bodies immune defense system. JimBob, Sat, 7th Jun 2008
You're right - but why the itch?
The damaged nerves in the skin are trying to "knit" together again so that might be why or your auto-immune system is reacting badly at the sting. rosalind dna, Sat, 7th Jun 2008
It's got nothing to do with nerves knitting back together or autoimmune manifestations I'm afraid.
Is it a happy accident for the mosquito then that the irritant makes us scratch the bite site, so bringing more blood to the skin surface for the mosquito to come back and feed on again? opus, Wed, 30th Jul 2008
I hate mosquitos!! They love me and eat me up! I am the worlds worse scratcher.... although I have seen children scratch them till they bleed slightly also.....
BY THe way Long time no see.. welcome back Opus! Karen W., Wed, 30th Jul 2008
Thankyou Karen W- it's nice to be back! opus, Thu, 31st Jul 2008