The dark-scaled form of Culiseta longiareolata (Macq.) was found near Bloemfontein in South Africa. Breeding took place in various kinds of flooded pools, small containers and drinking troughs. It was multivoltine and overwintered as hibernating second-, third- and fourthinstar larvae and adult females. Laboratory colonisation was easily accomplished. Adults were maintained alive at 23°C and 70% relative humidity, and survival rates were high for 40–50 days. Starved females fed readily on blood from pigeons at night or on a 3:1 mixture of human blood and 10% sucrose solution from cotton-wool pads. Mating swarms were not observed in the field, but swarming activity occurred in laboratory populations provided with simulated dawn and dusk conditions. The fact that mating activity could be readily induced at any time was taken to show that it is not governed by a rigid endogenous rhythm. Egg-rafts varied in shape from round to oblong. Oviposition was invariably nocturnal. Some substance, probably emitted by bacteria, served as an oviposition attractant. The anterior pole of each egg lacks an exochorion and is hydrophilic. The posterior pole bears a lipid droplet. The exochorion is sculptured, the sculpturing consisting of bosses connected to one another by bridges constituting the outlines of a series of pores. The exochorial pattern varies in different regions of the egg. Pupation and emergence occurred mainly at night, and there was an approximately normal sex ratio.