A method is described whereby tsetse visiting a stationary ox can be observed through a one-way glass screen in the presence or absence of man. Under the latter condition six times as many adults of Glossina pallidipes Aust. perch and feed on the ox. In G. morsitans Westw. most flies land in the head-down position and are unaffected by man's presence, but in the absence of man there is a four-fold increase in the number which land and feed in the head-up position. Calculations indicate that in the absence of man virtually all G. pallidipes adults attracted to the ox alight on it, and nearly all attempt to feed. Man's presence not only repels many tsetse completely but also inhibits the landing response of many of those that do approach the ox.

The biology of Hydrotaea irritans (Fall.) has been studied at Weybridge since 1973. The flies have failed to mate in cages and only those which have been fertilised before capture have laid viable eggs in the laboratory. In experiments in 1975–76 flies in the field emerged from June onwards but development of the ovaries (noted in seven stages) to the point of ovi-position was not completed until September. Some 1400 larvae were established in culture and, although they had reached a maximum size by January, they continued to feed until 14 March. Pupation lasted for 25 to 32 days during 6 May to 12 June and a total of 185 flies emerged from 4 June to 9 July. The results of these experiments confirm that H. irritans does not diapause and that the species is univoltine.

The males of Heliothrips haemorrhoidalis (Bouché) are very rare and the species is thelytokous. Mutation of genes controlling male characteristics will therefore not be subject to selection, and so structural variation in these males is of no taxonomic significance. It is concluded that haemorrhoidalis and ceylonicus Schmutz represent one species in which the females vary in size, sculpture and colour throughout the tropics.

Engorged Culicoides specimens were collected in light-traps from 16 sites in Kenya. The precipitin test was used to identify the blood-meal source of 682 specimens of 21 species over a period of five years. Culicoides pallidipennis C, I. & M. and C. schultzei (End.) were shown to feed mainly on cattle and to a lesser extent on sheep, and thus could be involved in the transmission of bluetongue virus. C. cornutus De Meillon, C. milnei Aust. and C. zuluensis De Meillon are probably not common enough as feeders on cattle and sheep to play more than an incidental role as vectors of bluetongue. C. schultzei is probably also important in the transmission of ephemeral fever. No groups of vertebrates other than Bovidae were implicated as virus reservoirs.