Culex mosquito can be visibly distinguished from other mosquito at the egg, larval and adult stages. The adult Culex is generally brown to dark brown. Culex mosquito do not have any white band on their abdomen compared to Aedes mosquito. For the female Culex, the length of the maxillary palps is less than half of the length of the proboscis, compared to Anopheles mosquito which have maxillary palps as long as the proboscis. In addition to that, the resting position of the adults of these three genera is quite different. The adult Culex and Aedes rest almost parallel to the surface whilst the adult Anopheles rests at an angle of 450 from the surface.
Another significant characteristic that differentiates Culex mosquito from the others is the laying of eggs. Culex females lay eggs in a mass called an egg raft on the surface of water while most of the females of the other genera lay individual eggs. The eggs are white when first laid and later darken tan to black. After a day or two, these eggs will start to hatch, allowing tiny white larvae to emerge. Identification of Culex at the larval stage can be tricky. One of the simple characteristics is the presence of an air tube also known as a siphon which is used for breathing. Anopheles larvae do not have siphons whilst larvae of Aedes possess shorter siphons compared to Culex larvae. Differentiation between Culex and other genera of mosquito at the pupa stage is more difficult and can only be done under a microscope.