Release of the chrysopid, Chrysoperla cornea Stephens, at a rate of ca. 335 000 eggs per hectare, reduced significantly the numbers of apterous adults and nymphs of the green apple aphid, Aphis pomi DeGeer, on dwarf apple trees. Greater reduction in aphid numbers occurred in 1984 than in 1985, and the efficiency of the predator might have been influenced by the predator:prey ratios (1:10 and 1:19) used and by the mean daily temperature that occurred during the test periods. Application of azinphosmethyl (Guthion 50% wp, 0.105 and 0.075 kg AI/100 L) did not adversely affect predation of apterous A. pomi by larvae of C. carnea.

First-generation mullein bug, Campylomma verbasci (Meyer), nymphs damaged four major cultivars of apple in commercial and research orchards from 1982 to 1984. In commercial orchards, C. verbasci was ranked among the top three pests in 22 of 40 samples collected at harvest, and its damage exceeded the economic injury level of 1% culled apples in 17 of the samples. Injury was greatest in "Delicious" cultivars, for which a linear relationship was derived between population density and damage at harvest. Economic injury levels of one and four nymphs per tap are proposed for cvs. Golden and Red Delicious, respectively, in British Columbia.

Cyrtogaster vulgaris Walker, a pupal parasite of the alfalfa blotch leafminer, Agromyza frontella (Rondani), acts as a secondary agent as well. The adults, which deposit their eggs within host puparia, apparently do not discriminate between healthy leafminers and those parasitized by Dacnusa dryas (Nixon). The egg and larval cephalic structures of C. vulgaris are described and illustrated and the final-instar larval skins of the two parasite species are compared.

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.

Two viruses, one a nuclear polyhedrosis virus and the other a granulosis virus, were applied in an attempt to initiate epizootics in populations of western spruce budworm, Choristoneura occidentalis Freeman, on Douglas-fir trees, Pseudotsuga menziesii (Mirb.) Franco, in southeastern British Columbia. Two 172-ha plots were aerially treated in 1982 with 9.0 kg of lyophilized, virus-infected larval powder that was formulated in an emulsifiable oil tank mix and applied at 9.4 L per hectare. Each plot was treated when larval populations were at the peak of the fourth instar. The nuclear polyhedrosis virus was applied at 5.4 × 1011 polyhedral inclusion bodies per hectare and the granulosis virus at 1.7 × 1014 capsules per hectare. Results showed that the granulosis virus treatment caused 34.6% population reduction (Abbott’s formula) and the nuclear polyhedrosis virus 51.8%. Larvae from treated and check plots were reared individually in the laboratory and the incidence of viruses, parasitoids, and successful adult emergence was recorded. Studies m these plots continued in 1983 and 1984. Although vertical transmission of both viruses was evident, their impact on budworm mortality was less than in 1982. Consequently, the epizootics were not sufficiently intense to control the target insect population.

A mark–recapture study examined the spring flight dispersal of the ambrosia beetle, Trypodendron lineatum (Olivier), in an even-aged second-growth coastal forest in British Columbia. Pheromone-baited traps were placed in circular traplines at distances from 5 to 500 m from a central release location to (1) examine the relationship between wind direction and beetle catches in traps arranged around the release point, and (2) evaluate beetle catch characteristics when distances to baited traps were varied. A total of 29 800 marked beetles were released in three experiments. Upwind flight was most strongly exhibited at 5 m, with an upwind trend at 25 m, and no consistent flight pattern at 100 m, when wind movement was significantly directed. When the closest attraction was 100 m from the release point, beetles were caught uniformly in all directions indicating that flight was non-directional with respect to wind, for light wind speeds. Catches at 500-m traps tended to be downwind, thus beetles capable of flying that distance were ones that were flying with the wind. Equal numbers of beetles were captured at 5, 25, and 100 m despite increased intertrap spacings of 8, 20, and 32 m, respectively. A higher proportion of beetles were captured at 100 m when close-range traps at 5 and 25 m were not present.

The immature stages of Neotephritis finalis (Loew.) are described and figured. Notes on the biology and the larval feeding damage to cultivated sunflowers also are given.

A review is given for the genus Obtusicauda Soliman in America north of Mexico. The subgenus Artemisaphis Knowlton and Roberts is restored to its original rank of genus. The species Obtusicauda essigi Soliman, O. jonesi (Gillette and Palmer), O. albicornus (Knowlton and Allen), and O. flavila (Knowlton and Allen) are considered to be synonyms of O. coweni (Hunter). The species O. cefsmithi (Knowlton and Allen) and O. zerohypsi (Knowlton and Allen) are considered to be synonyms of O. filifoliae (Gillette and Palmer). A key and an annotated list are given for the remaining six species of Obtusicauda.

The new association approach for selecting biological control agents has been reanalyzed in the light of recent data. The results support the conclusion that the new association approach is ecologically and statistically sound. One of the major advantages of this approach is its capacity to control native pests, which make up 60–80% of all pests. The specificity of biocontrol agents newly associated with the target hosts is similar to other biocontrol agents. In addition, the new association approach is as safe as the old association approach in terms of environmental risks. Recent trials in the use of new associations have been most encouraging, and suggest that this approach should contribute to the future success of biological pest control worldwide.

The development of gypsy moth larvae was monitored in the laboratory on the foliage of 39 species belonging to 18 genera in the Araucaraceae, Cupressaceae, Ginkgoaceae, Pinaceae, Taxaceae, and Taxodiaceae. Larval survival through successive molts, time of larval development, live female pupal weights, and adult female production of ova were measured as indicators of host plant suitability for the gypsy moth. The criteria for distinguishing the most suitable hosts were as follows: (1) greater than 80% survival of first-instar larvae, (2) development to pupation in less than 41 days, (3) female pupal weights over 1099 mg, and (4) the production of more than 350 ova. The most suitable species were in the Pinaceae, in particular, Cedrus deodara (Roxb. ex Lamb.) G. Don, Larix decidua Mill., and Picea pungens Engelm. The least suitable species were in the Cupressaceae, Ginkgoaceae, and Taxaceae. First-, second-, and third-instar larvae often differed in their ability to survive on new foliage compared with foliage from the previous year. Overall, first-instar larvae successfully developed into adults on 20 of the species tested but second-instar larvae developed into adults on 29 of the species tested. First- through fourth- or fifth-instar larvae failed to develop into adults on eight of the species tested.

A dark green aphid was isolated from a greenhouse colony of green peach aphid, Myzus persicae (Sulzer), in Fredericton, N.B. The green aphid was shown to conform taxonomically and biologically to the recently named species Myzus nicotianae Blackman, except for its rare production of alatae. It is reported for the first time on greenhouse-grown potato where its population development is similar to that of the yellow holocyclic M. persicae from the same colony. The vector efficiency of the green and yellow aphids for potato virus Y0 is similar. The yellow aphid tends to be more susceptible to insecticides than the green aphid. Myzus nicotianae was not found in aerial aphid samples taken in New Brunswick in 1967 and 1987.

Adult pear psylla, Psylla pyricola Foerster, from commercial pear orchards near Wenatchee, WA, were tested using a slide-dip technique for susceptibility to fenvalerate over a 5-year period from 1984 to 1988. Results were compared with those from similar tests using psyllids from an unexposed population near Corvallis, OR. During 5 years, resistance of adults to fenvalerate increased by 16- to 32-fold at Wenatchee while that of the Corvallis population did not change. In 1988, tests with five pyrethroids and pyrethroid – piperonyl butoxide combinations indicated that pear psylla adults also were resistant to permethrin and flucythrinate but not to fenpropathrin or cyfluthrin which contain a cyano group that reduces their susceptibility to oxidase metabolism. Piperonyl butoxide synergism was proportional to the level of resistance, indicating that resistance is probably due to increased mixed function oxidase activity. Implications of this study to control of post-diapause winter form adults in commercial pear orchards is discussed.

Male mullein bugs, Campylomma verbasci (Meyer), were attracted in field experiments in the Okanagan Valley of British Columbia to traps baited with females, extracts of crushed females, or Porapak Q-captured volatiles from females on common mullein, Verbascum thapsus L. Extracts from the female head and thorax attracted more males than did abdominal extracts. Traps baited with C. verbasci of both sexes caged together were not attractive. Analysis by coupled gas chromatography – mass spectrometry revealed n-butyl butyrate and n-hexyl butyrate in female extracts and captured volatiles, but only the latter compound in male extracts. However, these esters were unattractive, either alone or combined. We suggest that Porapak Q-captured volatiles could be used in pheromone isolation, and that pheromone-baited traps have promise in monitoring populations of C. verbasci.

Agrypon flaveolatum (Gravenhorst), introduced from Europe to control the winter moth, Operophtera brumata (L.), on apple and oak in Nova Scotia and British Columbia, was distinguished from the closely related native species, A. provancheri (Dalla Torre) and A. alaskensis (Ashmead). A detailed study of the three species revealed that they could be distinguished by specific morphological characters and by results of morphometric analyses of intra- and inter-specific variation of number of annuli of the antennal flagellum. The history of introductions of both the host and parasite is reviewed, including an account of host–parasite interactions. All of the characters defining species entities were found to be correlated with differences in host insect, host plant, and distribution.

Most of the range of the red turnip beetle, Entomoscelis americana Brown, lies within the Western Cordillera and Interior Plains physiographic regions of North America between latitudes 45°N and 68°N. Entomoscelis americana is associated mainly with three types of vegetation: forests, forest–grasslands, and grasslands. Temperature adaptations in the egg, larval, pupal, and adult stages that permit E. americana to occupy its present range are outlined. Host plant abundance may be the main factor preventing eastward extension of its range. Climate and host plant abundance together appear to limit E. americana to low altitude locations north of 60°N latitude. Eight of the temperature adaptations of the egg and adult stages together seem to limit southward extension of the range. Entomoscelis Chevr. appears to have a Holarctic distribution, with 11 species in the Palearctic region and one (E. americana) in the Nearctic region. The stock giving rise to E. americana may have migrated to North America during the Pleistocene when the Bering land bridge was in existence. Entomoscelis americana likely spent the Wisconsinan glacial period south of the ice in the Western Cordillera and (or) in central United States.

Two field experiments were conducted to determine if Orthotomicus caelatus (Eichhoff) was attracted to pine bolts infested with conspecifics and to assess the roles of the sexes in attraction. Traps baited with pine bolts artificially infested with males attracted both males and females, but traps baited with uninfested bolts or bolts with females caught very low numbers of beetles. The addition of females to bolts with males reduced the attraction produced by males in a second experiment. Bolts with males and females did not reduce the attraction produced by other males in adjacent bolts, suggesting that females do not produce a masking pheromone. The pheromone system of O. caelatus is similar to those known for other species in the Ipini in which males initiate gallery construction, produce an attractant, and attract females and opportunistic males. Preliminary gas chromatographic analyses of extracts of hindguts and frass from males boring on pine bolts suggested the presence of ipsdienol and ipsenol, two commonly occurring pheromones in other species of the Ipini. The pheromone system of O. caelatus is discussed with regard to the complexity of the pine bark beetle guild in the southeastern United States.

Deutonymphs and adults of Oregonacarus rivulicolus gen.nov., sp.nov. are described, and distributional data are given for this and other species of Anisitsiellinae inhabiting seepage water habitats in western North America. A revised key to the nearctic genera of Anisitsiellinae and a brief discussion of their phylogenetic relationships are presented.

Massive quantities of webbing and overwintering eggs produced by Schizotetranychus schizopus (Zacher), covering the trunks of two willow trees growing near Radium Hot Springs, British Columbia, are reported. This was the most extensive concentration of overwintering eggs and webbing, produced by spider mites under natural conditions, known to the authors.

A nesting aggregation of Lasioglossum (Evylaeus) cooleyi (Crawford) was studied on the campus of the University of British Columbia in July 1988. This species is primitively eusocial. There was a 7.3% size difference between queens and their workers; 40% of the latter had well-developed ovaries and 14% were mated. Thus, this species is one of the most primitively social members of its subgenus. The cells were not gathered together in a cluster or surrounded by a cavity. This species has a haploid chromosome number of 18, the largest number yet recorded for any Halictid bee.

Resistant potato plants influenced the parasitoid Edovum puttleri Grissell directly, as well as indirectly through eggs of the parasitoid’s host, the Colorado potato beetle, Leptinotarsa decemlineata (Say). In the field, E. puttleri parasitized more egg masses on plants with no glandular trichomes or with glandular trichomes bearing only enclosed droplets of exudate than on plants with two types of glandular trichomes (one with exposed droplets and the other bearing enclosed droplets). Trichomes with exposed droplets entrapped numerous parasitoids. Although rearing L. decemlineata on resistant plants influenced many of the beetle’s life-history traits, it did not affect the suitability of their eggs for development and survival of preimaginal E. puttleri. However, eggs from L. decemlineata that were reared on resistant potato plants reduced the longevity of the parasitoids and also reduced the number of hosts (eggs) killed by parasitoids.