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The chaetotactic nomenclature proposed by Lindquist and Evans (1965) for the Gamasina, using the family Ascidae as examplar, is adopted for use in the family Phytoseiidae. Probable setal homologies were determined by: examining and comparing ontogenetic relationships in both the Phytoseiidae and Ascidae; standardizing the shape and size of the dorsal shield of exemplars from 7 genera of Phytoseiidae and one of Ascidae in order to compare standardized, transformed setal positions; examining the spatial relationships between setal and pore positions. The technique used to standardize the shape and size of the dorsal shield is described. The setal nomenclature adopted for each of the genera of Phytoseiidae is discussed and presented in diagrammatic form. Ventral chaetotaxy in the Ascidae and Phytoseiidae is also discussed.

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The basic biological characteristics of two species of predacious phytoseiid mites, Phytoseiulus persimilis and Amblyseius andersoni, were studied in the laboratory. The results showed that P. persimilis had a higher reproductive rate during a shorter oviposition period and produced more progeny than A. andersoni. Amblyseius andersoni is considered to be along-lived phytoseiid and its rate of predation on adult female spider mites was higher than that of P. persimilis. With both species, unmated females did not reproduce and consumed significantly fewer prey than mated females.

This paper constitutes a "stocktaking" of biological control in Canada. The success or failure of each of 31 Canadian biological control projects is assessed. Past experiences in Canada are analyzed, and recommendations for future work are made. The meaning of the term "control" is defined in an economic context. Lloyd's (1960) suggestion regarding the influence of host plant longevity on the success of biological control is rejected, and a new concept based on the type of injury inflicted by the pest is substituted. There is a discussion on the philosophy of biological control and some of the popular misconceptions regarding it. Some dangers of biological control are suggested. Smith's (1929) analysis of the population effects of multiparasitism is challenged. The simultaneous introduction of many exotic species of parasites and predators is not favored and a strong plea for more discrimination and caution in the selection of species for introduction is voiced. The need for research in this field is emphasized, and fields of research are suggested. The philosophy of a biological control research program is outlined.