Adhesive traps can be used in greenhouses and outdoors. They are essential means of detecting insect pests and monitoring the development of their populations. They can also be used to control pests when used at high density (high number of traps per plant or m²). Yellow traps catch whiteflies, leaf miners, aphids and sciarid flies. The traps are always applied above the tips of the plants, raising the trap as the plants grow. The exception is for sciarid flies, as the traps are placed at ground level. The density of traps to be placed is 5 per 100 m² when used for pest detection and monitoring. When used as a means of control, the density should be 1 per 2 m² and in indoor crops it should be 1 per m².