| Summary: | Since the advent of DDT and other new organic insecticides, phytophagous mites, particularly those of the family Tetranychidae, have occupied increasing attention from economic entomologists. When these insecticides were applied, as controls for certain insect pests, it was found that in almost every case populations of mites increased to such an extent that further chemicals were required to control the mites. Theories were early advanced, and later substantiated, that the newer insecticides, particularly DDT, were harmful to predators of mites. Mites increased to tramendous populations when released from the control previouely exercised by their predators. It, therefore, became imperative for economic entomologists not only to find newer and better acaricides, but also to determine through biological studies what arthropods are predacious on plant-feeding mites. This study belongs to the latter category. It was initiated in 1950 with a threefold objective: to determine what species of Tetranyohid mites are of economic importance in Manitoba; what predators are present for natural control; and what relative value each predator bas as a natural control factor. The information contained herein was accumulated during the years 1950 and 1951. Prior to this time no work had been done on predators of mites in Manitoba. In two years the important mite species and their principal predators have been identified.[...]
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