In the Zambezi Valley of Zimbabwe, ULV applications of non-residual insecticide (endosulphan and NRDC 161) were made to a 1.8 x 1.8 km block of woodland infested with Glossina morsitans morsitans Westw. and G. pallidipes Austen. The recapture rates of marked flies released in the centre of the block, and recaptured in odour-baited traps in and around the block, indicated that the insecticides killed about 97% of flies that had been released 1-4 hr before spraying. Catches of unmarked male G. m. morsitans in the centre of the block declined after the insecticide applications, but there was no clear effect on catches of female G. m. morsitans and both sexes of G. pallidipes. Data for the movement of marked flies suggested that the minimum daily rates of movement were about 700 m for male G. m. morsitans and about 800 m for the other tsetse. An increase in dawn temperatures, from 17.5 to 27.5°C, was associated with an increase in the rate movement of G. pallidipes in the early morning. The failure to detect changes in the unmarked populations of female G. m. morsitans and both sexes of G. pallidipes was attributed to the high mobilities of these flies and demonstrated that unmarked populations could not be studied satisfactorily in small plots; studies based on marked populations are recommended for such plots.

Following a long and varied history, Glossina control has become increasingly dependent upon the use of insecticides. There have been substantial successes with the use of chemicals, but reinvasion has been a constant, wide-spread problem. It is increasingly obvious that tsetse control must be approached on a large scale and requires international funding. Despite the proven ability of insecticides to reduce tsetse infestations there is a general reluctance to expand their usage and non-chemical methods are receiving increasing priority. In this paper, an attempt is made to put tsetse control into perspective. The literature relating to various insecticidal methods and tsetse control operations involving ground spraying, helicopter residual spraying, application of low dosage aerosols from fixed-wing aircraft and chemically impregnated traps is reviewed, and research and development relating to both the entomological and application aspects of chemical control are discussed. It is concluded that, given our present state of knowledge, insecticides provide the most reliable method for large-scale tsetse eradication. Of the methods available, applications of low dosage aerosols from fixed-wing aircraft have the greatest potential for rapid and effective control over large areas with minimal risk of non-target contamination, although refinements to improve efficiency and economy are needed. An integrated insecticidal approach combining the attributes of various chemical, and possibly nonchemical, control methods with the proven large-scale capability of spraying from fixed-wing aircraft could provide a realistic answer to the persistent Glossina and trypanosomiasis problems.

Summary A study to investigate some aspects of the social biology of bushbuck (Tragelaphus scriptus Pallas 1776) was carried out in a 2.59 km2 study area in the Nairobi National Park, Kenya. Observations throughout 1966 using binoculars and photography identified thirty‐one male and thirty‐three female bushbuck. Together with an estimated fourteen juveniles, the density in the study area was 30.1/km2. Distribution is aggregated with loose family groups concentrating around forest edge areas near to dams or river pools. Home ranges varied from 20 ha for sub‐adult males to 5 ha for adult males and 2.5 ha for females. Bushbuck are predominantly solitary with 53.7% of all sightings being of lone animals; 14% of associations were of an adult female with a single calf and the commonest adult association (8%) was a single male with a single female. There is a strong mother‐young relationship. Very young calves lie in concealment away from the mother during the early days of their lives. Agonistic encounters between males vary in intensity from play fighting in sub‐adults to lateral intimidation display and overt conflict. The presence of a female, assumed to be in oestrous, sometimes stimulates males to intense aggression and at such times, a single male forms and defends a mating association with the female. Territorial defence was not observed. Bushbuck often associate with other species, particularly impala and baboons. They show a negative reaction to tick‐birds which may be one reason for their often having heavy infestations of ticks and flies. Predator avoidance relies largely on crypsis and ‘freezing’ followed by rapid flight through dense vegetation. Résumé Une étude pour approfondir quelques aspects de la biologie sociale du Guib harnaché (Tragelaphus scriptus Pallas 1776) fut entreprise sur une surface de recherche de 2.59 km2 au Parc National de Nairobi, Kenya. Tout au long de 1966, des observations faites aux jumelles et par photographies, ont permis d'identifier 31 mâles et 33 femelles de Guib. Avec une estimation de 14 juvéniles, la densité dans la zone d'étude est de 30.1/km2.

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A study of wing fray and ovarian age in females ofGlossina morsitans centralisMachado in Botswana confirmed that although the relationship between the two was strong it varied from month to month. The rate of wing fray with age was greatest in the hot dry season, and in both very young and very old females it was affected by humidity. Both age and activity are manifested as fraying of the wings, but it is considered unlikely that wing fray could be used as a reliable measure of either. It is suggested that wing fray may impose a physiological limitation on the lifespan of tsetse flies and may consequently be a factor in population regulation.