Relationships between the start of male swarming for Anopheles coluzzii (in VK7) and An. gambiae s.s. (in Soumousso) and environmental conditions. A) Mean ± standard error (s.e.) temperature (solid line, left axis) and humidity (dashed line, right axis) when first male(s) observed swarming, B) light intensity at start of swarming and C) time at which first male(s) observed swarming (solid line) and time of sunset on swarm monitoring days. For each data point n = 20 (for each species, the same five swarm sites monitored on four consecutive days each month). Note: tick marks on the x-axis mark the boundaries between months.