The Influence of Spray Programs on the Fauna of Apple Orchards in Nova Scotia. III. Mites and their Predators

Abstract

Three mirids, Diaphnidia pellucida Uhler, Hyaliodes harti Knight, and Campylomma verbasci (Meyer), are effective predators of the red mite and probably of the clover mite from early in June until the latter part of July. These three species are the only important predacious mirids under the conditions of the present spray practices in Nova Scotia. Gilliatt (2) has given an account of the life-histories of the three specics and discussed their importance in the natural contrnl of the red mite, and his account need not be repeated here. The three mirids are often the only important predacious species in many commercial orchards during the summer months because of the destruction of I. tiliae and H. faurei by the sulphur sprays emploved around the bloom period. Their presence in such orchards is in itself evidence that neither bordeaux mixture nor flotation sulphur reduces their numbers. Observation on a considerable number of occasions showed that iron carbamate has no effect on these mirids. An opportunity to test some of the common spray chemicals on two of the species was presented in the F. Palmer orchard at Berwick in 1947. Two trees were sprayed with each of the materials listed, and the insects were collected as they dropped on two trays, of 32 square feet each, which had been placed beneath the trees.