Relative abundances of An. gambiae s.s. and An. arabiensis larvae in 1997, 2009 and 2010. The white and black pies are proportions of An. gambiae s.s and An. arabiensis, respectively. The left, middle and right pie graphs are results of 1997, 2009 and 2010, respectively. A number below each pie graph is the number of collected larvae, and a number in parentheses is the number of habitats.