House density over time in linear (top) and natural logarithm (bottom) scale to evaluate systematic change over time. Circles denote observed daily mean density and the black lines show the interpolated series of mean house density over 5-day intervals. Grey lines depict interpolation during the longest time without field samples (December 2008 to April 2009). First rain events are shown by green lines (dates listed above). Sample sizes of mosquitoes and collection days are the same as in Extended Data Fig. 1b.