Greetings.

Animals do it too. From insects or skin conditions of whatever be the cause.

Is there a benefit to the microorganisms on skin that cause the itching, as rising blood flow from scratching ? If it is a reaction to a chemical there is no microorganism to favor. Either from some skin condition cause or from an insect or contacting a plant; scratching produces a highly pleasant rewarding sensation. Can end damaging the skin from fingernails abrasiveness.

Mosquitos, fleas... are bothersome if the 'bite' is felt but the later scratching is pleasant, no doubt.

55 minutes ago, Externet said:

Greetings.

Animals do it too. From insects or skin conditions of whatever be the cause.

Is there a benefit to the microorganisms on skin that cause the itching, as rising blood flow from scratching ? If it is a reaction to a chemical there is no microorganism to favor. Either from some skin condition cause or from an insect or contacting a plant; scratching produces a highly pleasant rewarding sensation. Can end damaging the skin from fingernails abrasiveness.

Mosquitos, fleas... are bothersome if the 'bite' is felt but the later scratching is pleasant, no doubt.

I always think Evolution with this sort of question. The brain rewards the body for health enriching behaviours, you are very hungry and eat it feel pleasant, eating keeps you alive.

You wake a numb arm it feel unpleasant, blood starts to return it feel pleasant again, normal blood flow good, ischemia bad.

What of an itch? Well removing an insect is better than one your skin potentially spreading disease and or biting you but the scratch itself can break the skin opening you up to (literally) infection.

I had a quick search and found this which mentions pain receptors overriding the itch sensation.

https://www.webmd.com/skin-problems-and-treatments/scratching-feels-good