Arthropods like mosquitoes are well-known vectors which are mainly involved in the transmission of pathogens to different human and vertebrate diseases. Most of the pathogens like viruses and nematodes are transmitted by mosquitoes. Controlling vector populations by using actinobacteria can be particularly very effective. Actinobacteria which contain also non filamentous forms of bacteria which produce a large number of biologically active secondary metabolites. Even though many antibiotics have been developed from actinobacteria, not much work have been conducted in the field of pest control. The actinobacteria and their metabolites effectively control mosquito populations and the transmission of diseases by them. The microbial metabolites have many advantages over synthetic chemicals because many of them are host-specific and safe for beneficial organisms. Due to this species-specific effect, microbial pesticides are more reliable to control mosquito populations. These types of metabolites have to be evaluated for the development of novel insecticides for vector control. Some studies have reported the mosquitocidal effects of actinobacterial metabolites like tetranectin, avermectins, spinosad, macrotetrolides, etc; they have less or no residual effect in the environment. This chapter focuses on the mosquitocidal effects of actinobacteria and their metabolites.