Adult C. quinquefasciatus is a medium-sized mosquito and is brown in colour. The body is about 3.96 to 4.25 mm long. While the main body is brown, the proboscis, thorax, wings, and tarsi are darker than the rest of the body. The head is light brown with the lightest portion in the center. The antennae and the proboscis are about the same length, but in some cases, the antennae are slightly shorter than the proboscis. The flagellum has 13 segments that may have few or no scales. The scales of the thorax are narrow and curved. The abdomen has pale, narrow, rounded bands on the basal side of each tergite. Males can be differentiated from females in having large palps and feathery antennae.
The larva has a short and stout head. The mouth brushes have long yellow filaments used for filtering organic materials. The abdomen consists of eight segments, the siphon, and the saddle. Each segment has a unique setae pattern. The siphon is on the dorsal side of the abdomen, and is four times longer than its breadth. The siphon has multiple setae tufts. The saddle is barrel-shaped and located on the ventral side of the abdomen with four long anal papillae protruding from the posterior end.
The southern house mosquito can transmit zoonotic diseases that affect humans and wild and domestic animals, such as lymphatic filariasis, avian malaria, St. Louis encephalitis, Western equine encephalitis, and West Nile fever. It causes infection through biting during blood meal. In the southern U.S., it is the primary vector of St. Louis encephalitis virus. In India and Southeast Asia, it is the primary vector of Wuchereria bancrofti, a nematode that causes lymphatic filariasis. It acts as an intermediate host for the helminth parasite by harbouring the larval stages. It also transmits Plasmodium relictum, a malarial parasite of birds, and is the principal vector in Hawaii. It is the definitive host for malarial parasite as it harbours the sexual cycle.
The Brown House Mosquito is a medium sized mosquito. The female is pale brown with darker brown thorax with paler markings. The male has large palps and feathery antennae, the female has smaller palps and less hairy antennae. Adult mosquitoes are active during the warmer months and usually attack people in the middle of the night indoors and outdoors. They are also attracted to birds. the habitat is closely associated with human habitation and common in urban areas. Like all mosquitoes, the female feeds on blood before producing her eggs. The Brown House Mosquito feeds on bird blood and also human blood. All Culex species lay their eggs in a raft, with about 300 eggs in a raft. Can breed in polluted water. Larvae are aquatic with a pair of spiracles on the second last abdominal segment used for breathing at the water surface. The larvae have tufts of bristles from many of the body segments.
The Brown House Mosquito is found in all states of mainland Australia. It is less common south of central highlands in Victoria. The Brown House Mosquito is a significant domestic pest in urban areas, and will often bite indoors. It is not a significant vector of human viruses but is an important vector of fowl pox.