A study was made of the effects of some insecticides on the metabolites of adult German cockroaches (Blattella germanica (L.)), by comparing the glucose, glycogen, fat, and water constituents of normal and exposed whole insects. Pieces of filter paper were impregnated with 5% concentrations of DDT, dieldrin, methyl parathion, and Strobane (terpene polychorinates (65% chlorine)) in peanut oil. Insects were exposed to the various insecticides by being caused to walk on the pieces of filter paper for 2-minute periods. Insects exposed to DDT showed that 62% of glucose, 73% of glycogen, and 16% of fat were utilized in 3 days. Insects exposed to methyl parathion showed a 55%, 64%, 0%. decrease in metabolites, respectively. Insects exposed to Strobane showed a 57%, 56%, 19% decrease in metabolites, whereas those exposed to dieldrin showed no change. There is thus some evidence to support the hypothesis that a reduction in metabolites is associated with the killing action of some insecticides, but also, that not all insecticides have this effect. Evidently dieldrin kills by some mechanism different from that operative with the other insecticides tested.