The effects of odours, wind direction and wind speed on the distribution of Glossina (Diptera: Glossinidae) and other insects near stationary targets

In studies in the Zambezi Valley of Zimbabwe, Glossina morsitans morsitans Westw. and G. pallidipes Aust. were captured on electric nets at various points around stationary targets. The distribution of flies was affected by wind direction, wind speed and the presence or absence of an attractant odour consisting of carbon dioxide and acetone. The distributions suggested that tsetse attracted to baits by visual stimuli alone fly first to a point just downwind of the baits, where the perception of odour is important in host recognition. Changes in the distribution of catches when odour was used suggested that the distributions could form useful indices of assaying attractant odours in the field. Data for Muscidae, Tabanidae, Asilidae and Hymenoptera are also presented.