Development inhibitors, that are being worked on so intensively now, seem to be one of the most promising tools of insect control. Monsanto 0585/2,6-di-tert-butyl-4 (a,a-dimethylbenzyl) phenol/ belongs to this group of compounds. It is highly active against mosquitoes Anopheles, Aedes, Culex and Psorophora, including species that are resistant to chlorinated and organophosphorus insecticides. The aim of this work was to get the initial data on absorption and excretion of this compound by insects that are needed for the further and more detailed study of action mechanisms of MON 585 and analogous development inhibitors. The present work is fulfilled using the compound Monsanto 0585, labeled by 14C. The preparation was applied to an experimental reservoir with Aedes cantans (Mg.) larvae under simulated natural conditions.