Calibration of trap catches and net catches for estimating population densities of the bush fly Musca vetustissima (Diptera: Muscidae)

Population densities of male and female Musca vetustissima Walker were estimated from recapture rates of marked flies in baited fly traps. Marked flies of laboratory and field origin were equally trappable. Trap catches of field flies were also compared with net catches for which the human collector was the source of attraction, and relationships are presented for estimating population densities based on both sampling methods. Estimates of fly density from trap and net catches at fixed locations have similar precision, coefficients of variation being approximately 55% for both males and females of M. vetustissima. Comparison of estimated fly densities (flies/ha) and annoyance indices, estimated numbers of flies approaching a collector each minute at 29.5°C, in ‘good’ and ‘bad’ fly years suggests that M. vetustissima is a potential nuisance whenever population densities exceed 1000 flies/ha.