For example, bed nets, window screens on homes, or protective clothing can help reduce the likelihood of contact with vectors. To be effective this requires education and promotion of methods among the population to raise the awareness of vector threats. Chemical control Insecticides, larvicides, rodenticides, Lethal ovitraps and repellents can be used to control vectors. For example, larvicides can be used in mosquito breeding zones; insecticides can be applied to house walls or bed nets, and use of personal repellents can reduce incidence of insect bites and thus infection. The use of pesticides for vector control is promoted by the World Health Organization (WHO) and has proven to be highly effective. Biological control The use of natural vector predators, such as bacterial toxins or botanical compounds, can help control vector populations. Using fish that eat mosquito larvae, the use cat fish to eat up mosquito larve in pond can eradicate the mosquito population, or reducing breeding rates by introducing sterilized male tsetse flies have been shown to control vector populations and reduce infection risks. Legislation United States In the United States, cities or special districts are responsible for vector control. For example, in California, the Greater Los Angeles County Vector Control District is a special district set up by the state to oversee vector control in multiple cities. See also Mosquito control Public health Soil-transmitted helminth Waterborne diseases References Epidemiology Pest control techniques