The mosquitoes (family Culicidae) are at the centre of worldwide entomological research primarily because of their medical importance as vectors of dangerous diseases, such as malaria, yellow and dengue fever, encephalitis and lymphatic filariasis. More than half of the world’s population lives under the risk of becoming infected by the causative agents of these diseases. Estimates made by the World Health Organisation (WHO), show that many hundreds of millions of people become ill, and some million people die annually (WHO, 1993). Although approximately three quarters of all mosquito species occur in the humid tropics and subtropics, mosquitoes are not just a problem of these regions. They may also cause a considerable nuisance in temperate latitudes. The mosquito species most commonly involved are the so-called floodwater mosquitoes, such as Aedes vexans and Ochlerotatus sticticus in river valleys that regularly flood, the snow-melt mosquitoes, e.g. Oc. communis, Oc. punctor, Oc. hexodontus in swampy woodlands and tundra areas, the halophilous species Oc. caspius and Oc. detritus, which breed particularly in the shallow lagoons found along the coasts of southern Europe, Asia Minor and north Africa, or the rock-pool mosquito Oc. mariae found along parts of the mediterranian rocky coasts, where mass occurrences can become a great nuisance. Culex pipiens pipiens biotype molestus, which is known as the “house mosquito” because of its presence close to human settlements can likewise make itself noticed in temperate zones as a nuisance.