Pregnant females of Glossina morsitans morsitans Westw. were offered choices of larviposition sites in the vicinity of various models and patterns. Ground-level surfaces of black, green, white or red were not attractive. Vertical surfaces did not attract a majority of flies, but 50% of those that settled on them gave birth in that region of the chamber. Shade cast by horizontal surfaces was attractive, but shade cast by vertical objects was not. Models with an enclosed space were attractive, but larviposition rarely occurred within the model, probably because flies do not readily enter cavities unless the temperature is very high. Among patterns presented at a distance, a simple unbroken area of black was more attractive than equivalent areas in the form of stripes, etc. No distinction was made between stripes presented vertically, horizontally and at an angle. Models representing logs or trees with rot holes were not attractive. Models with subterranean cavities, even a simple trench, were attractive. Loose sand was not more attractive than sand glued to a substrate, but there was an indication of a preference for larger particles. No evidence was obtained for the hypothesis of Nash et al. (1976) that a larval pheromone attracts gravid females to larviposition sites.

Activity in virgin and pregnant females of Glossina morsitans morsitans Westw. was very low and mostly took the form of short bursts of flight. Recently-fed virgins and females in early and mid-pregnancy were least active. In late pregnancy, activity increased and more walking occurred. In all classes of females, activity was least around midday, but the V-shaped curve became less pronounced as parturition approached. There was evidence of a slight preference for black over white surfaces when landing but a clear preference for black resting sites. Virgin females preferred to alight and rest on vertical surfaces at the borders of areas of visual contrast; pregnant females preferred to alight and rest on horizontal surfaces and showed no attraction to regions of contrast. In a horizontal light gradient, pregnant females selected lighter resting sites as the day progressed. In late pregnancy, there was an increasing tendency to rest in darker sites. Increasing the temperature in the light gradient caused an increase in activity around 34°C and a switch to photonegative behaviour. After larviposition, the females became strongly photopositive even at high temperature (38°C), but after a feed they reverted to the ' normal' photonegative response to high temperature.