Mosquitoes are small, flying insects that can transmit diseases to humans and animals. Female mosquitoes require a blood meal in order to produce eggs. They undergo complete metamorphosis with four life stages: egg, larva, pupa, and adult. Some common mosquito species in the US include Aedes aegypti, Culex pipiens, and Anopheles quadrimaculatus, which can transmit diseases like dengue, West Nile virus, and malaria respectively. Mosquitoes are infected when they feed on an infected host and can then transmit pathogens during subsequent blood meals.