There are over3,500species of mosquito throughout the world.But it is only the female of the species which bites as she searches out nourishment for her eggs. Mosquitoes find their human prey using a combination of sensory signals including light, shape,color,heat global atmospheric the temperatures are presently in a warming phase that began250-300Years ago Speculationson the potential impact of Continued on human health often focus on mosquito-born diseases.Elementary models suggest that higher global temperatures will enhance their transmission rates and extend their geographic ranges.However, the histories of three such diseases malaria,Yellow fever, and dengue.This experiment study was done to detect the susceptibility of mosquito larvae to the aqueous solution of the Diazinon pesticides and to determine LC50(lethal concentration) of Diazinon on larvae and to draw the toxicity line.Eleven different concentration of Diazinon were prepared (3×10-2,15×10-3,6×10-3,4.5×10-3,3×10-3,2.1×10-3,1.5×10-3,1.2×10-3,9×10-4,6×10-4,3×10-4).The experiments were done4times and the average gave percentage of death as follows (100%,92%,85%,80%,70%,66%,63%,60%,55%,25%)Regression line was drown for each experiment (1,2,3,4, and the average) and LC50was found to be (2.8×10-3,7.2×10-4,5.2×10-4,1×10-4).Diazinon pesticide maybe used on mosquito larvae control because it is effective.More studies are needed to determine an exact LC50and what type of environmental of larvae in which the insecticide may be used.