At dusk it emerges to look for a meal. Other species feed in the daytime. This skin reaction is your immune system trying to repair the damage the mosquito has done by piercing your skin. Mosquitoes inject their saliva which contains an anticoagulant. Blood is able to flow freely and is sucked up the proboscis.
Mosquitoes can transmit diseases through their saliva.
This species can transmit encephalitis and is the major carrier of dog heart worm in Hawaii. Other species are wanted for carrying diseases such as yellow fever, dengue fever and malaria. Behind your knees, ankles, elbows and neck.