The boreal zone of Canada extends across the continent over millions of square kilometres. Characterizing the insects of this cool temperate zone is especially important for an understanding of the Canadian fauna in general, and for northern forestry. The boreal zone supports simple coniferous forests with some deciduous trees and an understory of a few common vascular plants, mosses, and lichens. This enormous area of apparently similar vegetation nevertheless shows very great spatial and temporal heterogeneity, with a wide range of subhabitats. Aquatic habitats of many different kinds are especially well represented in the zone. The diversity of terrestrial habitats is maintained chiefly by disturbance, especially fire and seasonal flooding, and contributes greatly to faunal diversity.

About 22 000 insect species are estimated to occur in the zone, far fewer than in more southern zones. Northern taxa, notably Diptera, are relatively well represented. The distributions and patterns of variation of the species are summarized. About half have transcontinental ranges, and many occur also in forested habitats in the western mountains south of the boreal zone. About 8% of the species appear to be holarctic. Few species that occur in the boreal zone are strictly confined to it, however. Generalist species in fresh water and other widespread habitats are conspicuous. Many species are centred farther south, and extend northward into the zone to varying degrees.

Adaptations to northern conditions have been reported in many boreal insects. For example, the short growing season is reflected by the prevalence of univoltine species. Insects survive the long cold winters by cold-hardiness and dormancies. Species from disturbed habitats disperse widely. The limited diversity of resources is confirmed by the fact that the food range of some groups of herbivores is wider than in their southern relatives.

Boreal ecosystem relationships are complex, especially relative to the arctic. Numerous associations among insects, and between insects and other organisms, have been demonstrated. However, some evidence suggests that the structure of northern biotic communities might depend more on the tolerances of individual species than on interactions among the species.

The population dynamics of boreal forest insects, notably the spruce budworm, are discussed. In view of the spatial and temporal complexity of the boreal zone, the diversity of interactions with abiotic and biotic factors, and the prevalence of data that correlate with rather than explain population changes, our current failure to understand “outbreaks” of certain boreal insects is not surprising, because many factors probably combine to determine the population of a given species at a given lime and place.

Information on most aspects of the composition and biology of the boreal fauna is incomplete. Data on boreal species have been collected chiefly in southern transitional ecosystems adjacent to boreal zones, rather than in truly boreal systems. Basic taxonomic information on several important taxa, as well as detailed taxonomic and morphometric information about individual species, is especially scanty. However, substantial and coordinated studies of boreal faunas will yield information of great interest and value. Some approaches relevant to further work in taxonomic and ecological arenas are suggested.

Electroantennogram (EAG) responses from male Cydia strobilella (L.) indicated that (E)-8-dodecenyl acetate (E8-12:Ac) was the most stimulating of the dodecenyl and tetradecenyl compounds assayed. Field-screening tests, which included compounds previously reported as attractive, demonstrated that only E8-12:Ac was effective. The optimum trap dosage was 0.3–3 μg on red rubber septa. Catches of males were greater when traps were hung in the upper crown of either white spruce or black spruce.

White fir cones were sampled for insect damage from wild stands in California and Nevada during 1984–1986. Insects were recovered from cones and seed damage was partitioned by insect species. The important phytophagous insects were separated into guilds: the cone- and seed-mining guild, Dioryctria abietivorella Groté, Eucosma prob. siskiyouana (Kearfoot), Cydia prob. bracteatana (Fernald), Barbara sp.; the seed-feeding guild, Megastigmus pinus Parfitt, M. rafni Hoffmeyer, Earomyia abietum McAlpine; and the scale- and bract-feeding guild, Asynapta hopkinsi Felt, Dasineura prob. abiesemia Foote, Resseliella conicola (Foote), Strobilomyia abietis (Huckett). Total damage by insects varied by year and site, reaching a maximum of 47% in 1986 on one site and a minimum of 12.5% in 1984 on another. Abortion and incomplete development also were major factors in the production of sound seed. Populations of white fir cone and seed insects varied with cone crop but also were affected by the occurrence of cone crops on alternate hosts. During most years, the seed-mining guild insects were the major cause of seed damage.

Larvae, deutonymphs, and male and female adults of Platyhydracarus juliani sp.nov., and adults of P. parvipalpis sp.nov., are described from rheocrenes and small streams in western North America. The genus Platyhydracarus gen.nov. is proposed and diagnosed, based primarily upon the presence of genital acetabula both in the gonopore and on acetabular plates flanking the gonopore, and of a group of thickened setae anterior to the gonopore, in male adults. Possible relationships between Platyhydracarus and other Athienemanniidae are discussed, and a new key to the genera of Athienemanniinae is presented.

The first record of Dipalta serpentina Osten Sacken, 1877, preying on larvae of Myrmeleon immaculatus DeGeer, 1773, was by Smith (1934: 136-137), who stated that the fly larvae were “parasitic” on the antlion larvae. Cole and Schlinger (1969: 251) stated that the fly larva of this species “…is parasitic on the larvae of Myrmeleontidae.”

Although the fly larvae may prey upon the larvae of the antlion, we have established that they definitely prey upon the antlion pupae (Fig. 1). Judging from the emergence dates (early September 1988) of the flies, each had preyed upon an antlion pupa within its cocoon. Each antlion cocoon had one hole in it. An examination of the contents of each antlion cocoon revealed the cast skin of the antlion larva and the empty, clear skin of the antlion pupa. The pupal skins were not split open, which they would have been if the adult antlion had emerged. They were shrivelled, and looked much as if the contents had been sucked out.