Estimation of the efficiency of the biconical trap for Glossina fuscipes fuscipes along the lake Victoria shore, Kenya

Prior to estimating the efficiency of the unbaited biconical trap for Glossina fuscipes fuscipes Newstead (Diptera:Glossinidae) the flying height of the insects was estimated using 1 m2 electrified nets placed at 0 and 4 m above the ground level. The degree of avoidance of these nets by the flies was determined by comparing catches in traps surrounded and those not surrounded by incomplete rings of nets. On the basis of the catches in traps surrounded by nets, the expected catches on both sides of the nets were computed and compared with the observed catches, to further estimate this degree of avoidance. About 48% of males and 35% of females were captured above one metre. An average of 61% of males and 40% of females appeared to avoid the nets. Between 18% and 40% fewer tsetse were caught in traps surrounded by an incomplete ring of nets of respectively 1 m and 2 m radius than in traps not surrounded. After corrections for net avoidance and flying height, it appeared important to determine the optimum radius for the incomplete ring of nets for a reliable efficiency estimate.