A space spray is when a pesticide that is applied as very tiny droplets, the droplets float in the air in a localised space and kill flying insect that come in direct contact when the fly through the treated area. Surface spray is when a pesticide is applied as tiny droplets on a surface, as insect travel across the treated surface the droplet adhere to body and consequently kill the insect. This surface spray is more efficient and longer lasting but tends to have a slower effect than space spraying.