This study was carried out on distribution, density, host plant, and natural enemies affecting its population fluctuation of Aleyrodes proletella L. (Hemiptera: Aleyrodidae) on collard during the years of 2016-2017 in Düzce province in Western Black Sea Region. Aleyrodes proletella was widespread in all districts of Düzce province and the infestation rate was 84.3%. The highest infestation rates were determined in Akçakoca (97.8%), Yığılca (93.3%), Gümüşova (88.9%), Kaynaşlı (84.4%), Cumayeri (82.2%), Gölyaka (80%), Çilimli (75.6%) and Central (75%) districts, respectively. Hosts of A. proletella except collard was determined that white cabbage (Brassica oleracea L. var. capitata) and Lapsana communis L. subsp. intermedia (Bieb.) Hayek plant which is called as common nippleworth belonging to the Asteraceae (Capparales) family. Parasitoid of A. proletella was detected as Encarsia tricolor Förster (Hymenoptera: Aphelinidae), and predators of A. proletella were found as Clitostethus arcuatus Rossi (Coleoptera: Coccinellidae) and Chrysoperla carnea Stephens (Neuroptera: Chrysopidae).