w -Fluoroalkyl- and w -fluoroacyl-containing lipids were evaluated as potential delayed action toxicants for the bait block method of subterranean tennite control. Studies of metabolism of the parent compounds and of a set of glycerol and cholesterol derivatives showed that both w -fluoroalkyl and w -fluoroacyl moieties are readily removed and catabolized in vivo, provided that at least one ester function is also present in the substrate. The extension of the tests from a simple petri dish assay to simulated field trials using vacuum-impregnated bait blocks suggested that the long-delay time materials may not be as effective as chemicals which were attractive, more toxic, and had delay times of only 12 to 24 h.