A key to the common Calliphorid flies of Peninsular Malaysia is presented. Illustrations of the genitalia of some rare species, list of new localities, altitudes and other ecological data are also presented. The following species were recorded for the first time from Peninsular Malaysia; Catapicephala sinica, C. kurahashii, Taninanina javanica, Hemipyrellia tagaliana, Lucilia sinensis, Blaesoxipha kasterni, Boettcherisca javanica, Parasarcophaga misera, P. orchidea, P. albicephs, Sarcosolomonia crinita, Thyrsocnema bornensis, Sarcorohdendorfia antilope and Lioproctia pattoni.
The resistant level of the houseflies to six kinds of insecticides, DDT, Resmethrin, DDVP, Baytex, Sumithion and Diazinon, was examined on the seven strains collected in Malaysia. It was found that their susceptibility is rather higher than that of the Takatsuki strain which is a standard strain in Japan. However, their susceptibility to Sumithion was the same or slightly lower than that of the Takatsuki strain. The resistant level to five of six kinds of insecticides was the highest in the strain of Cameron Highland. The values were close to Singh's data in 1973, and this means that the resistance of the houseflies to the insecticides is increasing in Malaysia.