Sampling Adults with Non-attractant Traps

Adults of haematophagous Diptera, especially mosquitoes, are usually caught by using human or animal baits or in light or carbon dioxide traps. Most of these attractant traps collect predominantly unfed females orientated to host-feeding. The use of different baits or attractants usually results in different groups of species being collected, e.g. anthropophilic or ornithophilic species. Often attractant traps are used specifically to collect certain species for isolation of viruses or other pathogens, and in this case the absolute numbers collected rather than the efficiency of collection of different species takes priority. Sometimes, however, especially in ecological investigations, more representative samples of mosquito populations are needed. Because of the virtual impossibility of finding an attractant trap that will sample equally all species, non-attractant traps are preferred. A disadvantage of non-attractant traps, however, is that because they catch mosquitoes only in their immediate area the numbers obtained are small unless mosquito populations are large. All traps discussed in this chapter sample the aerial population, hence the numbers caught depend not only on population density but also on the flight activities of the individuals.