This communication presents the results of an experimental study with phosphamidon on the digestive proteases and lipase of Schizodactytus monstrosus. The enzymes estimated are the protease, trypsin, chymotrypsin and lipase in the gut lumen and gut tissue of the insect, Both the treated and control females show significantly greater activity than male individuals. The enzymes exhibit varying results following the treatments with phosphamidon which depends upon the exposure-time. All the enzymes of both sexes show optimal activities in the treated specimens after 6 hours of treatment with phosphamidon. Although the activity of each enzyme increased in each of the gut fraction (fore, mid and hind) of both sexes yet some quantitative differences among them have been noticed. Gradual and significant declining effects have also been found after 12 hrs., 18 hrs. and 24 hrs. of treatment. The activities observed after 24 hours exposure of phosphamidon treatment appeared significantly low when compared to control. The most interesting observation is that this is true in case of all enzymes irrespective of sex and gut fraction. The physiological significance of these results are discussed in relation to the control of enzyme secretion and synthesis.