Abstract
Microencapsulated diazinon (MC) showed superior residual effect to emulsifiable concentrated diazinon (EC) against the German cockroaches. The observation of the body-cleaning behaviour of cockroaches, the chemical analysis of diazinon and the microscopic observation of the MC proved the easy attachment of the MC to their body surface and the massive ingestion into their digestive tracts. Thus, the MC in the guts of cockroaches plays an important part of its killing activity as the MC on the body surface does. Due to this bimodal entry, the short-contact and residual toxicities of MC are fortified over that of EC.
