Whiteflies (Homoptera: Aleyrodidae) are one of the most important key pests of many crops throughout the world. In this examination, the effective at weekly releases of Encarsia formosa Gahan for greenhouse whitefly control, Trialeurodes vaporariorum Westwood in commercial gerbera greenhouses, on three colours: yellow, white and pink was determined. Parasitoids were released in one, two and three ratio per each pot and compared with control treatment. Released parasitoids in two and three ratio treatments could decrease population of greenhouse whitefly under the economic damage threshold and no meaningful difference observed, and these treatments had a significant difference with treatments one and control. This shows that treatment one couldn’t decrease pest population under the economic damage threshold. In addition, the pest population on yellow flowers were more than other colours and had a significant difference with them.
