Why do mosquitoes and chiggers bite certain people but not others?

Skin smell & CO2. An old outdoorsman from alaska swore by a method of eating mosquitoes and regarded that a smell came to his skin that repelled live mosquitoes. Who knows?
Mosquitoes adore certain . Because of intense work in malaria, mosquitoes have been studied too. Genetic play a role in who mosquitoes like--if dad was always bitten, chances are you will be too. They seek out co2, heat and quick movement. Love beer drinkers, sweat, smelly socks &limburger cheese odor. Vision isn't great so tend to go for large men vs small women. You can camouflage from them: in a green forest wear green and they miss you for a big bush nearby. Seriously.
? . Some people seem to attract more bugs and get more bites than others and I have notice (personally) that healthy people seem to get bitten more often. This is only my observation however.