A new class of insecticides, the 1,4-disubstituted 2,6,7-trioxabicyclo[2.2.2]octanes, was prepared either by acid-catalyzed condensation of a 2-substituted 2-(hydroxymethyl)-l,3-propanediol with a trimethyl orthocarboxylate or by Lewis acid catalyzed rearrangement of a 3-substituted 3-[(acyloxy)methyl]oxetane. Compounds of high toxicity to houseflies or American cockroaches have 4-substituents such as n-propyl, isopropyl, -, sec-or tert-butyl, cyclopentyl, cyclohexyl, or phenyl and 1-substituents such as cyclohexyl, cycloheptyl, 4-cyanophenyl, 4-nitrophenyl, 4-halophenyl, or 3,4-dichlorophenyl. The toxicity to houseflies is generally increased by injection and by piperonyl butoxide indicating that the insecticidal activity is limited by the penetration rate and oxidative detoxification. The bicycloorthocarboxylates have a positive temperature coefficient in poisoning houseflies and act at the cockroach neuromuscular junction to inhibit GABAergic synaptic transmission possibly by closing off chloride channels.