Bluetongue virus (BTV) infection is prevalent among the cattle popolation in Taiwan and two BTV strains were isolated from goat in Kinmen County and from dairy cattle in Pingtung County in 2003. To date, the Culicoides vector responsible for BTV transmission in Taiwan has not remained unknown. The purpose of the study is to collect the insect samples from farms with high BTV serological prevalence. Through the way of BTV-specific nucleic acid detection, the competent vector for BTV transmission could be found.