To compare different sampling techniques, blackflies were captured along six Swedish rivers in 2001 and 2002, using two fundamentally different methods: (1) daytime trapping with a vehicle-mounted net, and (2) exposure of CO 2 -baited traps. The methods were selectively different for different species of blackflies. Some species were caught relatively more frequently by vehicle trapping and others by CO 2 trapping. Only rarely were species catches proportionally similar between the two methods. We suggest that the different catch success reflects differences in host-searching behaviour in the species present and that the sampling methods are complementary
