Anopheles density in the village of Barkoumbilen during the study period. Total number of Anopheles females (A. gambiae s.l. and A. funestus) per person per night and their relative frequencies during the study period are reported. A. gambiae (empty area), A. funestus (grey area). Bars denote 95% confidence interval (CI). Data are based on pyrethrum spray catches carried out monthly (12 catches/month) as indicated. The total number of captured mosquitoes were as follows: Aug '94, n = 275; Sept '94, n = 547; Oct '94, n = 576; Nov '94, n = 235; Mar '95, n = 20.