Abstract:Multitude frozen sh were strewed around the Tsunami disaster areas from huge freezing storehouses in the northern Japan on March 11, 2011. ere were outbreaks of blow ies from rotten sh in the following months. We carefully worked out on the control strategy a er investigating rotten sh in the early May from Tanohata-town, Iwate Prefecture, the northernmost study city, to Kesennuma-city, Miyagi Prefecture, the southernmost study city. e larvae of Calliphora nigribarbis were abundant in the early May in the rotten sh, and a few of the adults were found around houses at that time. From the end of May to June, the adults of this species were stormed to the residents. en, Phormia regina and other blow ies were replaced to C. nigribarbis. e pest control operators from all over Japan were requested to spraying heap of rubble and rotten sh from May to September in the Tsunami disaster areas. We selected Etofenprox emulsion according to the e cacy and avian low toxicity as insecticides and Fenitrothion EC as for the rest. Fly population declined in the end of July by the insecticide spraying, replacement of gavages rubble-mountains or dried-up rotten sh. e high susceptibility of the blow ies to the insecticide was found.