Fig. 2

Schematic diagram of camera fields of view for recording mosquito flight within flight arena. Red and blue lines show camera fields of view, green lines show 3D capture area, grey shading represents flight arena (as seen in Fig. 1a-x). a Side view: 3D capture area ~85 cm at base and maximum height of 80 cm, upwind edge ~20 cm from upwind screen. b Crosswind view: Left panel shows human volunteer’s position (white line) and right panel shows CO₂ concentrations. Human volunteer sat in upwind odour delivery chamber (Fig. 1a-vii), corresponding to the left side of panel a, c and d, with head positioned as shown and waist at flight arena floor level. Host’s breath and additional CO₂ released at a height of ~35 cm. False colours show CO₂ concentrations across wind ~50 cm downwind of host (i.e. centre of 3D field of view) and highest concentrations (1,400–2,000 ppm) at a height of ~30 cm. Hence, human odour effectively permeated middle ~60 cm of the flight arena up to a height of ~30 cm, corresponding to the area in which mosquitoes were observed. Clean air corridors of ~30 cm wide lined both side walls and the area above ~50 cm throughout the flight arena. c Aerial view. d 3D projection; arrow indicates direction of air flow