Diseases transmitted by insects continue to have a major impact on human populations. Malaria, dengue, onchocerciasis, sleeping sickness and leishmaniasis all adversely affect man. Malaria is one of the most important causes of child mortality and reduces economic development in many countries, with agricultural productivity often greatly reduced, as many vectors are active in the wet season favourable for crop production. Vector control is crucial to reduce the extent to which drugs are needed to treat the diseases, as the parasite can become resistant, or the drugs are often too expensive fo