Introduction Culicoides biting midges are bloodsucking insects and they disturb human beings and animals by causing allergic reactions in the host. They also decrease animal products and kill animals as they transmit diseases (1-5). The number of the studies conducted to detect Culicoides species in Turkey increased in the last 25 years. Serious efforts to identify and document Culicoides species in Turkey began with Navai's PhD thesis (6), in which she documented the presence of 19 Culicoides species from Turkey. Jennings et al. (7) recorded 18 Culicoides species from the southwestern part of Turkey. Dik and Dinçer (3) collected 14,098 Culicoides specimens from Konya Province in the Central Anatolian Region. Yılmaz (8) detected 42 Culicoides species in Elazığ Province in the Eastern Anatolian Region of Turkey. In a study (9) carried out on Culicoides species in the Mediterranean Region, 24 Culicoides species were detected. The C. imicola Kieffer, 1913 and C. schultzei (Enderlein), 1908 complexes were reported to be in lower numbers, while the C. obsoletus complex was captured in high numbers in the Aegean Region of Turkey (10). Other studies carried out in relatively restricted areas followed these studies (11,12). The results of the studies performed in Turkey demonstrated that the C. imicola and C. schultzei complexes existed in the Mediterranean and Aegean regions while the C. pulicaris and C. obsoletus complexes were found in Central Anatolia and other parts of Turkey (13). There are two studies on the Culicoides fauna in the Black Sea Region of Turkey (11,14). However, they were carried out in the Central Black Sea Region, and there is no study found on Culicoides species in the Western Black Sea Region of Turkey. In this respect, the present study aimed to detect the Culicoides species in the Western Black Sea Region of Turkey. 2. Materials and methods 2.1 Localities This study was carried out in the Western Black Sea Region of Turkey: Bolu (31.78790°E 40.76908°N,