Leaf‐swallowing by chimpanzees Pan troglodytes has been hypothesized to control parasites, but it has not yet been shown to be associated with specific parasitic infections. This report takes advantage of a tapeworm infestation among wild chimpanzees to examine whether leaf‐swallowing was associated with the presence of tapeworms.

Leaf‐swallowing was monitored over 6.5 years in two chimpanzee communities in Kibale National Park (Uganda). In one community, tape‐worms ?Bertiella studeri were found only during a seven‐month period, when they occurred in every month. During this period, leaf‐swallowing occurred at an unusually high rate, and dungs that contained tapeworm fragments tended to contain whole leaves. These data suggest that tape‐worm infections increased the rate at which chimpanzees swallowed whole leaves. However, this does not mean that tapeworms were necessarily controlled as a result. © 1995 Wiley‐Liss, Inc.