trehalase inhibitors seem to have long-lasting effects on metabolism, suggesting that trehalase activity might also be reduced for considerable time spans. This has recently been confirmed for total trehalase activity in locust flight muscle.() because trehalase in locust flight muscle homogenates appears in different formd-soluble, overt and latent-with yet unknown locations and functions in vivo, a detailed study on the long-term effect s of a trehalase inhibitors on the various forms of the enzyme seemed desirable. It was expected that the inhibitory effects on the trehalase system of flight muscle would indicate possible functions of the different forms of trehalase in intact locusts and also shed light on possible relationships between them. For these reasons, locusts were injected with a sublethal dose of trehazolin and the following questions were addressed .