In the framework of a bluetongue surveillance program including clinical, serological, and entomological activities, Culicoides biting midges were light trapped weekly in two regions of central Italy, Lazio and Tuscany. In the period January 2002 through December 2005, 3,944 collections were carried out in 189 trap sites distributed in all the provinces of the two regions. Abundance data of C. obsoletus group were analyzed in relation to trap site altitude, distance from the sea, land use, and number of farmed animals. Species seasonality and overall temporal trend were also described. C. obsoletus was distributed over the whole study area, almost in all trapping sites and with high abundances. The species group was dominant among all captured Culicoides, with higher abundances recorded inland and in areas where land cover was partially or completely natural-wooded. Adults on the wing were caught all year round, with peaks in May–June and middle October. The observed trend through years recorded a peak during autumn 2002, in concomitance with a local epidemic of bluetongue.