Wheat grown as a banker plant hosts bird cherry-oat aphids (Rhopalosiphum padi), which serve as a host for the parasitoid wasp Aphidius colemani. The banker plant can be placed near a crop infested with other species of aphids that A. colemani also targets. Such use of banker plants is a useful—and green—tool for integrated pest management in greenhouses. (Photo credit: Tracey L. Payton Miller, Ph.D.)