The factors involved in the natural control of the most numerous aphids on cole crops were studied. During the 1957 season the cabbage aphid (Brevicoryne brassicae (L.)) was the most abundant aphid followed by the green peach aphid (Myzus persicae (Sulzer)), whereas the turnip aphid (Rhopalosiphum pseudobrassicae (Davis) was least abundant. In 1958 the order of abundance was: the green peach aphid, turnip aphid, and cabbage aphid. A parasite, Praon sp., attacked only M. persicae. Diaeretus rapae (McIntosh) and Empusa aphidis Hoffman attacked all three aphids. The ratio of parasitism was greatest in the most dense aphid population and smallest in the spare population. Coccinellids of the following species destroyed aphids: Hippodamia convergens Guerin-Meneville, Ceratomegilla macilata fuscilabris De Geer, and Coccinella transversoguttata Faldermann. Syrphids attacking the aphids were: Sphaerophoria cylindrica Say, S. menthastri (L.), S. robusta (Curran), and Mesogramma marginata Say.