All integrated vector management program mainly emphasis on application of biological agents. In the present study, the back swimmer, Anisops sardae H.-S.(Hemiptera: Notonectidae)and naid of Orthertrum chrysostigma (Burmeister) (Odonata: libellulidae) are common aquatic insects of the freshwater fauna communities in Mosul City. These insects are predators of dipteran larvae. Predation efficacy and selectivity, searching efficiency and predatory clearance rate were asessed. Stages of Culex pipiens melestus (Culicidae) and Chironomus minevah (Chironomidae) in the laboratory. It was found that single adult of A. sardea consumed 9.0,8.0,6.7and 6.7 of the four instars and pupae 5.3 of C. pipiens molestus and one of third O.chrysoslihma naid predated 8.7,6.7,6.3, and 5.3 of the mosquites larvae instars and pupae 3.3. Both applied predators were preferred. 3rd and 4rd mosquito larva linters when they were exposed the immature stages collectively. Also the predation efficiency increases up to 17% when the two predator species put together, which synergic each others in predation the prey. On the other hand, it was revealed that Odonate naids preferred chironomid larvae over culicid larvae. In the laboratory condition, the prey density effected inversely on searching efficiency.