Aerial view of the system for spatial repellency bioassays. The screen cage was made of mosquito netting suspended on a metal frame and surrounded by white foam board with blue and black fabric on each side. Two blood-soaked sanitary pads were set under the cage: one, impregnated with lemongrass oil, was placed in the treated zone, and the other, impregnated with hexane, was placed in the untreated zone. For further details see Materials and Methods section.