Seventeen species of Plecoptera were collected from 58 lakes situated along the Continental Divide in southwestern Canada. Four of the 17 species were found once. The commonest species was present in 25 lakes. At low to middle elevations stoneflies occurred in large lakes that had relatively low total dissolved solids and low maximum annual heat content. The distribution of the majority of species was restricted with respect to lake area and elevation. For example, some species were found only in large lakes at low to medium elevation (900 to 1700 m), while others were found only in small lakes at high elevation (1800 to 2400 m).

Artificial infestations of cereal aphids in caged plants were made at different growth stages of barley in the field in 1978 and 1979. Forty, 80, 160, and 200 aphids/tiller reduced grain yield significantly (P < 0.01) when introduced into caged plants at flowering and milky stages for 2 weeks. Only the 150 and 200 aphids/tiller-treatments gave significant reductions in yield when introduction was at the mealy ripe stage. Twenty aphids/tiller gave a significant reduction in yield only when they were introduced at the beginning of ear emergence and flowering, but not at the milky ripe stage. Significant reduction in percentage protein was obtained only when 160 and 200 aphids/tiller were introduced at flowering and milky ripe stages. The economic injury and threshold levels were calculated as 10–18 and 8–16 aphids/tiller, respectively, depending on rate of increase of aphids, costs of chemical control, and the value of the crop in 1978 and 1979.

Measures of pollen removal in the orchid Cypripedium acaule Ait. provided a retrospective method for estimating the activity of bumble bee pollinators in New Brunswick spruce-fir forests. Significantly lowered activity was observed in fenitrothion-sprayed forest as compared with unsprayed control areas. The difference is probably attributable to direct mortality of bees in sprayed forest.

Females of Microctonus vittatae Muesebeck reared at 20°C were darker in colour than females reared at 25°C but were lighter than those reared at 15°C. Temperature during the parasite’s larval or pupal development in the cocoon, or both, was apparently responsible for the colour differences. The observed effect of temperature is probably also associated with colour variability among adults of M. vittatae field-collected throughout the season.

Keys to adults and puparia of three Nearctic species are given, with an outline of distribution of each species. Melangyna tenuis (Osburn) and M. cincta, American authors not Fallén, are treated as synonyms of M. triangulifera (Zetterstedt). A lectotype is designated for M. guttata (Fallén). A new species is described from British Columbia.

Habitats and life cycles of five species of water striders were compared in south-central British Columbia. Three species of Gerris were bivoltine; both Limnoporus species were univoltine. Generation timing varied markedly among lakes and periods of maximum abundance for all species overlapped. Each species showed distinct association with a single type of habitat defined by vegetation structure. These associations separate most species among lakes and suggest that habitat is the most important resource axis for ecological separation of gerrid species on the Fraser Plateau.

The aquatic plants Utricularia minor L., Lemna minor L., and Elodea canadensis Rich. in Michx. were tested for their effects on the colonization of artificial ponds by mosquitoes and their predators. During the 11 weeks of sampling there were significantly fewer mosquito eggs, and hence mosquito larvae, in the plant-filled ponds than in plantless control ponds, and more predators in the Utricularia and Elodea ponds than in the plantless and Lemna ponds.

Male Ips paraconfusus selected a host, ponderosa pine (Pinus ponderosa), over a non-host, white fir (Abies concolor), only after the beetles had bored through the outer bark and into the phloem. Males, when given a choice between bark discs of these tree species in petri dishes, bored readily through the outer bark of either species. However, the beetles penetrated no more than 1 mm into the phloem of white fir, but they bored extensively in the phloem of ponderosa pine. The beetle’s preference for the pine over fir phloem was apparent with intact samples of phloem with the outer bark removed and with ground phloem. No preferences were apparent for the ground or intact pine or fir outer bark, with the phloem removed. The beetles bored preferentially in fissured as opposed to smooth outer bark of either tree. Beetles did not feed in the outer bark but did feed in the phloem of either species. In field experiments beetles attracted to logs of pine and fir bored through the outer bark of each species in nearly equal numbers. In white fir they re-emerged and departed soon after penetration of the phloem, whereas in ponderosa pine they continued excavation of tunnels in the phloem. In contrast, few beetles penetrated even the outer back of incense cedar (Calocedrus decurrens), another non-host species.

The Nearctic Idiocerini exclusive of the fauna of the Sonoran subregion are reviewed. The 68 recognized species are assigned to three genera: Idiocerus Lewis, Rhytidodus Fieber, and Balcanocerus Maldonado-Capriles. Three subgenera of Idiocerus are recognized, including I. (Liocratus) Dub. and I. (Populicerus) Dlab. (n. stat). Sahlbergotettix Zvk., 1953, Viridicerus Dlab., 1974, Tremulicerus Dlab., 1974, and Acericerus Dlab., 1974 are synonymized with Idiocerus Lewis, 1834.

Sixteen new species of Idiocerus are described: aureus, carolina, cedrus, freytagi, gillettei, immaculatus, inebrius, iodes, lucidae, midas, pericallis, taiga, unicolor, vanduzeei, venosus, and xanthiops. I. varions n. n. is created for varias DeLong & Hershberger, 1947 (nec Germar, 1818). I. lunaris Ball (n. stat.), I. obsoletus (Wlk.) (n. stat.), and I. raphus Freytag (n. stat.) are recognized as valid species for the first time. Twelve other species are removed from synonymy. I. verrucosus Ball is placed as a subspecies of I. musteus Ball (n. stat.). Five new synonymies are created: alnirubratus Bliven, 1955 = I. couleanus Ball & Pkr., 1946; nigrens DeL. & Cld., 1937 = I. distinctus Gill & Bak., 1895; duzeei Prov., 1890 and vagus Ball, 1902 = obsoletus Walker, 1851; and apertus DeL & Hbr., 1947 = I. verticis (Say), 1831.

Additional characters of the male antennae, male abdominal apodemes, and female ovipositor are described and illustrated. The phylogeny and hosts of the members of Idiocerus are discussed. Keys are provided to the genera of the Nearctic Idiocerini, and to the species of Idiocerus of the Nearctic region, exclusive of the Sonoran subregion, for both sexes.

Preconditioning of isolates of Beauveria bassiana (Bals.) Vuill. and Metarrhizium anisopliae (Metch.) Sor. with specific insects increases their virulence. An isolate of B. bassiana used two years previously in pathogenicity tests against spruce budworm, Choristoneura fumiferana Clem., required only one passage through this insect to attain 100% mortality in 48 h of incubation, whereas an isolate of M. anisopliae that was not previously used against this insect required four passages to attain the same degree of virulence as B. bassiana. Larvae of Laspeyresia youngana (Kft.), Dasineura rachiphaga Tripp, and Dasineura canadensis Felt were very susceptible to both fungi and 100% mortality was obtained in less than 48 h of incubation. Larvae of Lasiomma anthracina Czerny were much less susceptible. Puparia of both genera of Diptera were more resistant than larvae and required longer incubation to obtain 100% mortality.

This is to supplement a monograph on Aradidae of Canada published by the author in 1977 (The insects and arachnids of Canada, part 3, The Aradidae of Canada). A new species of the genus Aradus is described below.

The European corn borer, Ostrinia nubilalis Hübner, is known to attack nearly every herbaceous plant large enough for the larvae to enter. Although the borer is primarily considered a pest of corn, economic infestations in such New York crops as potatoes, gladiolus, and other large stem plants are not uncommon.

In 1977, 1978, and 1979, economic levels of borer infestations were observed in winter wheat. In 1977, the presence of borer in wheat was noted at a number of sites, but only a few cases could be considered economically significant. However, in the 1978 season, the presence of borer in wheat had become common and reports of economic infestations exceeding 5 or 10% were widespread in the western New York wheat growing region. In 1979, the problem of borer on wheat declined significantly, and of infestations located, only one could be considered of economic significance.