Canadian literature on the ecology, behaviour, and life-history is summarized for each of the eight species of sawflies, jointworms, and related insects, one species of earwig, eight of thrips, about nine of springtails, thirteen of mites, and one symphylan that are recorded as harming annual crop plants in Canada.

Systematics allows the extraordinary diversity of biological systems to be understood, and information about organisms to be organized and made accessible. Key patterns that help to interpret natural processes can be summarized, and biological traits predicted, by determining the relationships of natural taxa. Ecological roles are made visible and existing knowledge is made accessible only through specific names. Most organismic diversity is represented by terrestrial arthropods, but knowledge is very incomplete. Even for species found in Canada, half have not been described and the immature stages of most are unknown.Systematics supports entomology and underpins studies of biology in many different ways. From these roles, understanding is gained about diversity and evolution, distributions and biogeographically significant regions of the country, adaptations as related especially to species interactions and metamorphosis, and the application of systematics information. In addition, the values of basic systematic work, modern techniques, and long-term coordinated efforts in studying the fauna are emphasized.A coordinated study of diversity by systematists in conjunction with ecologists and others is required. Such a coordinated approach is timely given recent recognition that the world depends on self-sustaining but increasingly threatened biological systems. Diverse organisms maintain those systems but can be distinguished only through systematics. Adequate long-term support — for systematics positions, research collections, activities that include the preparation of basic works such as monographs, and educational facilities — is required to underpin the systematics component of such a coordinated study.

The large and complex genus Euxoa is divided into six subgenera: Orosagrotis, Longivesica, Euxoa, Chorizagrotis, Pleonectopoda, and Crassivesica. Orosagrotis and Chorizagrotis have until now been considered as valid noctuid genera by many workers. Longivesica and Crassivesica are here described as new. The taxonomy and distribution of North American species in all subgenera except the very extensive subgenus Euxoa are considered in the present paper. Only 49 species in a probable North American Euxoa fauna of some 200 species are included in the five subgenera reviewed here, however.Within the genus, species have been segregated into subgenera and species groups largely on the basis of the structure of the male genitalia, and particularly on the conformation of the vesica of the male. Keys to subgenera, species groups, and species are presented. No new species are described. Subspecies are not formally considered because an adequate analysis of the often complex geographic variation is beyond the scope of this paper.

Two behavioural extraction techniques, wet and dry extraction, were evaluated as to their relative efficiencies in removing invertebrates from samples of wet peat collected from a fen near Schefferville, Quebec. Dry extraction involved drying a substrate sample from above, forcing any macroinvertebrates contained therein to move downward out of the substrate matrix. In wet extraction, peat samples were suspended in a water bath where a vertical temperature-dissolved oxygen gradient had been established; invertebrates responded to the gradient by moving downward out of the sample and into the water bath. Wet extraction yielded approximately three times more invertebrates per unit volume of substrate than dry extraction, but the two extraction methods differed considerably in their ability to extract different invertebrate taxa. Dry extraction was more effective than wet for obtaining larvae of Tabanidae, Tipulidae, Empididae, and Dolichopodidae, but larval Chironomidae, sphaeriid clams, and oligochaete worms were collected more efficiently by wet extraction. Other invertebrate taxa were collected with approximately equal efficiency by both methods.

In their simplest form, crop models consist of regressions relating factors such as yield to environmental variables. Explanatory models also exist, with much physiological detail and responsiveness to meteorological and soil factors. Summary models can be derived from such large models, including the influence of pests. Of these major types of models, regression models are increasingly becoming widely used to optimize and integrate the many facets of cereal management in Western Europe. This fact suggests that crop manipulation is evolving toward optimal production management.