What do tsetse feed on?
Tsetse feed exclusively on blood but blood from some animals seems to be preferred to others.
For instance, many of the Glossina morsitans subspp. feed preferentially on wild pigs (warthog, bushpig) and buffalo. Others such as Glossina fuscipes feed on the monitor lizard. Where humans and their livestock are present, many of these natural hosts disappear but domestic livestock such as cattle and pigs act as ideal substitutes for these wild hosts. In some parts of Africa, people traditionally do not eat pigs and thus the wild ones are largely left alone. In these circumstances, tsetse are provided with a wealth of wild and domestic hosts and thus populations of tsetse thrive.
Clausen, P. H., Adeyemi, I., Bauer, B., Breloeer, M., Salchow, F. & Staak, C. (1998). Host preferences of tsetse (Diptera: Glossinidae) based on bloodmeal identifications. Medical and Veterinary Entomology 12, 169-180.