Tsetse populations can be monitored and effectively controlled using simple, inexpensive traps. These often use electric blue cloth, since this color attracts the flies. Early traps mimicked the form of cattle but this seems unnecessary and recent traps are simple sheets or have a biconical form. The traps can kill by channeling the flies into a collection chamber or by exposing the flies to insecticide sprayed on the cloth. Tsetse are also attracted to large dark colors like the hides of cow and buffaloes. Some scientists put forward the idea that zebra have stripes, not as a camouflage in long grass, but because the black and white bands tend to confuse tsetse and prevent attack.