Sticky trap studies on Simulium damnosum s.l. in northern Ghana.

The results of sticky trapping S. damnosum s.l. at several sites in northern Ghana are given. Yields were always very much lower than those which could be obtained by human bait catches, and caught flies tended to disappear from traps which were not emptied at least daily. Thus the technique offered little promise as a means of monitoring population fluctuations. Nevertheless some valuable information was obtained. Colour choice studies showed that hunting flies were attracted to dark blue substrates. In all situations the most shaded surfaces of the traps were preferred by alighting flies. The presence of S. damnosum in the canopies of trees was demonstrated for the first time. Flies were caught at heights above 6 m at three sites, the maximum height being 9.2 m, the height of the topmost trap. Among flies caught in the canopy of trees were nulliparous, parous and gravid females as well as males. Only in one catch, at relatively low levels in riverine trees, were blood engorged flies a noteworthy proportion of the catch.