To investigate whether H5N1 virus could survive in the blow fly C. nigribarbis, we monitored the titer of infectious virus in flies after they were exposed to the H5N1 avian influenza A virus (A/duck/Hyogo/35/2001) [10] . Fifty female blow flies (Kyoto strain C. nigribarbis), approximately 14 days old, were put into a 20 cm 3 fly cage for 3 h at 20 • C with a piece of cotton impregnated with 10 8 EID 50 /mL allantoic fluid from an H5N1 virus (A/duck/Hyogo/35/2001 [10] )-infected egg diluted with MEM diluents [11] . Following the 3 h virus exposure, the blow flies were individually reared at 20 • C or 10 • C until tested. Incubation at 10 • C was chosen because the average temperature around Tamba Town was 3.6 • C in February and 6.4 • C in March, with average daytime highs of 11.1 • C in February and 13.1 • C in March [12] .