In 2008, massive population of parasitoid Encarsia formosa was found for the first time in the greenhouses on the Laboratory Field of Biotechnical Faculty in Ljubljana (Slovenia). This species is known for a long time as effective natural enemy of the greenhouse whitefly, Trialeurodes vaporariorum, and other whiteflies in different parts of the world. 1306 wasps from genus Encarsia were found in nymphs of greenhouse whitefly. The most numerous was E. formosa (934 individuals), following by 367 individuals of E. tricolor, 4 males of E. inaron and a male of E. longicornis. Greenhouse whitefly parasitoid was determined on 14 host plants in the greenhouse and E. tricolor on 11 host plants in the greenhouse and on one host plant in the field. E. inaron and E. longicornis appeared only on one host plant in a greenhouse. For the time being the use of wasp E. formosa is not yet permitted in controlling greenhouse whitefly in Slovenia, but there is possibility to include it in the programs of biological control of pests on ornamentals and vegetable plants in the greenhouses. Consequently, the use of chemical insecticides will be reduced. V rastlinjakih na Laboratorijskem polju Biotehniške fakultete v Ljubljani smo v letu 2008 prvič našli številčnejšo populacijo parazitoida Encarsia formosa, ki je v svetu dobro znan naravni sovražnik rastlinjakovega ščitkarja, Trialeurodes vaporariorum, in nekaterih drugih vrst ščitkarjev. V ličinkah rastlinjakovega ščitkarja smo našli 1306 osic iz rodu Encarsia. Najbolj številčni so bili osebki vrste E. formosa (934 osebkov), našli pa smo še 367 osebkov vrste E. tricolor, 4 samce vrste E. inaron in enega samca vrste E. longicornis. Predstavnike vrste E. formosa smo našli na 14 gostiteljskih rastlinah v rastlinjakih, vrsto E. tricolor pa na 11 vrstah gostiteljskih rastlin v rastlinjakih in na eni rastlinski vrsti na prostem, medtem ko sta se vrsti E. inaron in E. longicornis pojavili le na eni rastlinski vrsti v rastlinjaku. V Sloveniji uporaba osice E. formosa za zatiranje rastlinjakovega ščitkarja še ni razširjena, vendar bi jo lahko vključili v programe biotičnega varstva okrasnih rastlin in vrtnin v zavarovanih prostorih in tako zmanjšali uporabo insekticidov.