Soil isopods plays critical role to increase soil fertility. Indiscriminate use of Herbicides on agricultural purposes resulted deleterious effects on the biology and species diversity of soil arthropods. The effect of sublethal concentration of a herbicide atrazine, were treated to find out the fecundity and moulting of a soil isopod (Cylisticus convexus). The LC 50 and LC 100 values of Cylisticus convexus were calculated. The safe and sublethal concentrations of atrazine were very low indicating high vulnerability of these isopods to agrochemicals. The safe level concentration of atrazine was 0.2897ppm. The moulting intervals of Cylisticus convexus showed variation between herbicide treated and normal Cylisticus convexus. Herbicide treated C. convexus showed drastic reduction in fecundity and also their moulting intervals were prolonged.