A successful technique for feeding colonies of Glossina morsitans morsitans Westw. and G. austeni Newst. in the absence of living 'hosts is described. Insects are fed through membranes made of silicone rubber or of agar and Parafilm, overlying blood pools poured onto grooved glass plates. The diet employed is fresh pig blood, collected at slaughter, and aseptic procedures are adopted at every stage of diet preparation and presentation. The reproductive performance of these in vitro-fed colonies in terms of adult survival, fecundity, and offspring size, is the same as that of colonies fed on living hosts, when compared over a long period of time. The fact that the technique is successful when used with a diet of pig blood, but is not successful when used with cow blood prepared in the same way, suggests that the technique per se is adequate to elicit a normal feeding response from these tsetse species. The nature of the nutritional superiority of pig blood is not understood.

Male and female Glossina morsitans morsitans Westw. which emerged from puparia produced by animal-fed and in vitro-fed colonies in England were marked distinctively with non-toxic paint and released into a natural habitat of G. morsitans and G. pallidipes Aust. in Rhodesia. Concurrently, adults of both species which emerged from locally-collected puparia were marked and released. Recaptures from artificial refuges, odour attractants and mobile baits at periods up to 59 days after release and at distances up to 1800 m from the release site indicated no clear differences between native G. morsitans and the two laboratory-reared groups in respect of body size, amount of fat present at emergence, survival, dispersal, availability to a range of baits, diet, speed of taking a first meal, wing damage and insemination rate. Although the blood-meal identifications for marked female G. morsitans were similar to those for both sexes of unmarked flies, blood-meals from marked males showed a relatively high proportion of bovid identifications. Unmarked flies caught were generally older than marked catches. The ratio of females to males in unmarked samples (1:1 for G. morsitans, 2:1 for G. pallidipes) was roughly double that in marked catches.

Fresh defibrinated bovine blood was superior to either haemolysed or freeze-dried defibrinated bovine blood when fed in vitro to female Glossina morsitans morsitans Westw. The presence of adenosine-5'-triphosphate (ATP) or other additives did not improve reproductive performance. The flies were able to compensate for considerable dilution of the blood with both serum and saline. Both parental and F t female size affected the weight of the F s puparia produced. The feeding of females on rabbits' ears on one day and in vitro on five days per week prevented any deterioration in performance over successive generations compared with a purely in vitro regime. A colony was established using this technique and results over a 13-month period were compared with those from a colony fed without rabbit supplement and another fed on rabbits only. The reproductive performance of females in the all-membrane fed colony deteriorated from generation to generation, while those in the rabbit supplement colony performed similarly to those of the rabbit-fed colony except that survival was better but fecundity was poorer and the puparia produced were smaller.

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Diagnosis was confirmed by the demonstration of cytoplasmic vacuolation and intranuclear inclusions in epithelial cells, and by observing the virus particles themselves by electron microscopy. Lesions persisted for at least 100 weeks.