Distribution: The species is known from the entire Holarctic region and is spread over whole Europe (Schaffner et al. 2001).

Habitat: According to Schaffner et al. (2001) Culex pipiens is actually considered as a plastic species, which is represented in Europe by two forms: C. pipiens pipiens and C. pipiens forma molestus; the pipiens form is described as ornithophilic, anautogenous, eurygamous and rural, and the molestus form as anthropophilic, autogenous, stenogamous and common in urban areas; both forms are not genetically isolated and seem to be a result of an ecological selection.

Aquatic stages of C. pipiens are found in all types of natural or artificial, temporary or permanent water bodies like hoof prints, pools, ditches, backwaters in streams, rice fields, marshes and containers such as tanks and butts; the water may be fresh or brackish, clean or contaminated and with or without emergent or overhanging vegetation (Mihályi 1959, Mohrig 1969, Briegel 1973, Rettich et al. 1978, Cranston et al. 1987, Becker et al. 2003). Larvae of the molestus form seem to tolerate strongly contaminations of waters and are mainly found in artificial habitats near human dwellings (Mihályi 1959, Mohrig 1969, Schaffner et al. 2001, Becker et al. 2003). Pursuant to Cranston et al. (1987) almost all British records of the molestus form are from underground or overbuilt sites, usually in complete or semi-darkness. Mihályi (1965) found larvae of the molestus form in cisterns and tanks in buildings, in sumps at the bottom of internal lift shafts or in containers and leakage pools in heated cellars and boiler rooms. In contrary larvae of the pipiens form are found in non-polluted habitats, they are more dominant at high altitudes and in the outdoor non-polluted breeding sites (Schaffner et al. 2001).

Biology: C. pipiens is a polycyclic species. Egg rafts are laid on the water surface (Mohrig 1969). They first appear in early April and hatching occurs over the ensuing few days; larval development is slow at the prevailing water temperatures and the first pupae are not found until late in May; rising temperatures produce more favourable conditions for oviposition and larval development becomes more abundant, reaching the highest density in summer (Onyeka 1980). Larvae may be found in lower abundance till October-November (Briegel 1973, Rettich et al. 1978).