As true flies, mosquitoes have one pair of wings, with distinct scales on the surface. Some species harbor specific morphological patterns. When at rest they tend to hold their first pair of legs outward.
Like all flies, mosquitoes go through four stages in their life cycles: egg, larva, pupa, and adult.
Mosquitoes living in regions where some seasons are freezing or waterless spend part of the year in diapauses; they delay their development, typically for months, and carry on with life only when there is enough water or warmth for their needs.
The adult mosquito emerges from the mature pupa as it floats at the water surface. Bloodsucking mosquitoes, depending on species, sex, and weather conditions, have potential adult lifespans ranging from as short as a week to as long as several months. Some species can overwinter as adults in diapause.
Each species selects the situation of the water into which it lays its eggs and does so according to its own ecological adaptations.
Some breed in lakes, some in temporary puddles. Some breed in marshes, some in salt marshes. Such differences are important because certain ecological preferences keep mosquitoes away from most humans, whereas other preferences bring them right into houses at night.