Although mosquito-borne diseases are common in many parts of the world, Malaria is the only human infection known to have been transmitted by mosquitoes in this country. Due to improved housing and related environmental factors, the malarial mosquito now frequents cattle sheds and stables, seldom feeding on human blood and the possibility of locally transmitted malaria is now extremely remote. The British climate is not suited to the transmission of tropical diseases such as filariasis, yellow fever and dengue. Some mosquito-borne viruses causing low fevers occur in Southern and Central Europe, but none have been detected in this country. British mosquitoes have a nuisance value and, in some cases, cause severe skin eruption and localised pain. Nevertheless, severe infestations can cause much distress and are a valid reason for mosquito control.