Mosquitoes are notoriously undesirable arthropods and are well–known for vector–borne diseases (e.g. dengue, filaria, malaria and Rift Valley fever). In Saudi Arabia, the most common mosquito-borne diseases include dengue, filarial, malaria and Rift valley fever. The aim of this study was to update the knowledge about the prevalence and distribution of mosquitoes in the southwestern region. Also to study the effects of several plant extracts and some insecticides against mosquito, (Culex pipiens). In this study, three plant species were selected (Rice bran , Milk weed and Juniper). The aquatic, ethanolic and acetonic extracts of these plants were tested against larval stage of Culex pipiens. Results showed that, twelve mosquito species were recorded and identified according to larval key proposed by Gad et al. (1964) and Harbach (1985, 1988). The encountered species belonged to 4 genera, namely; Anopheles (4 species), Culex (6 species); Aedes (One species), and Culiseta (one species). Culex pipiens was the most dominant one in Asir region. Culicine habitats during the present study gave a generalization of breeding sites that were shaded, vegetated, and had stagnant deep or shallow water, which are preferable for larval breeding...