Optomotor normal visual response of the locust Schistocerca gregaria was compared when injected (between 1st and 2nd thoracic segments) with 10, 5, 2.5 and 1.25 microg/g body weight doses of Permethrin after different intervals of time (just after injection, 10 and 20 minutes). LD50 value for Permethrin was calculated to be 3.0 microg/g. Results are analyzed statistically by t. test and ANOVA technique. It was noticed that there was a significant decrease of vision (P<0.005, Table II) in treated locusts and at the same time Permethrine effect is significantly time related (P<0.05, ANOVA, table III). Correlation between increasing age, weight and increasing toxicity has also been established. The inhibition of neural enzyme Cholinesterase with Permethrin and as a result more accumulation of acetylcholine at nerve junctions and less passage of the transmission of impulses thus less response from the locusts has also been explored and discussed.