Figure 3.

Overall density (number of mosquitoes/house) in treated (red) and control (black) villages over time, measured by pyrethrum spray collections in 25 houses/village every month until the first rain and every 10 d thereafter. The density of the molecular forms of An. gambiae and of An. arabiensis was estimated by multiplying the density of An. gambiae s.l. (upper panel) by the corresponding fraction representing the relevant taxon in the corresponding village and time period. The yellow shading denotes the period of treatment in treated villages (from the desiccation of the last larval site 10 km around the village and until the first rain).