Glossina vanhoofi Henrard has been found at the I.R.S.A.C. field station at Irangi in the Belgian Congo in dense rain-forest. The fly does not normally attack man and was collected only by looking for it in its resting places. The fly rests on small saplings, head down, at an average height of about 133 cm. A three-months' survey on a fly-round transecting three valleys and two hill-tops showed that the resting density (defined as the total number of resting flies observed per 10,000 metres of path) was correlated with the profile of the transect, the hill-tops yielding more flies than the valleys. The fly-round was worked three times a day and showed the highest density during early morning in all three months; in two of them there was little difference between midday and evening catches. The resting height varied in much the same way in all the sections of the fly-round and the average height remained virtually constant during the three months of the survey. There was a slight difference between the sexes as regards average resting height, the females perching somewhat lower than the males. The sex ratio of about 1:1 was very constant throughout the day and the period of the observations.

There is some evidence which seems to indicate that this species is strongly attracted to possible host-animals by a sense of smell.

Puparia have been found in “classical” sites, but the proportion containing living pupae was small. The duration of the pupal period is about 35 days under laboratory conditions at 26°C. and 90 per cent. relative humidity.

G. vanhoofi in captivity feeds readily on the porcupine, Atherurus africanus.