Twenty seven actionmycetes were isolated from desert soil of different Egyptian sites and tested for production of insecticidal agents against the 3^rd instar larvae of mosquitoes Culex pipiens. The obtained data exhibited that the isolate metabolites have a lethal effects. Metabolites of seven isolates cause 100 % total mortality. These isolates were identified as Streptomyces fungicidicus, Streptomyces griseus, Streptomyces albus, Streptomyces rochei, Streptomyces violaceus, Streptomyces alboflavus and Streptomyces griseofuscus. However, some isolate metabolites exhibited its insecticidal effect on the development of larvae. In addition, some pupal deformities (pupal-adult intermediate) were recorded by isolates no. A7, A8, A13, A24 & A26.