A comparison of the range of attraction of animal baits and of carbon dioxide for some West African mosquitoes

Experiments were carried out on the flight pattern of unfed female mosquitoes in an area of the Gambia adjacent to mangrove swamps. The mosquitoes were trapped in flight by the use of ramp-traps as they approached natural or simulated baits. The traps were arranged in series in four avenues of cleared bush, radiating out at right angles to each other. The baits were installed either at the centre of the cross formed by the avenue or at the outer end of one avenue. Trapping was carried out at six ranges simultaneously, extending from 5–80 yd (4·5–73 m) distance from the bait. The baits were either two small calves or carbon dioxide emitted from a cylinder at a rate equivalent to the expiration rate of the animals. A series of catches with no bait was also made.