Significant differences in age structure of grasshopper populations [Melanoplus sanguinipes (Fabricius), M. bivittatus (Say), and M. packardii Scudder] occurred in winter wheat and adjacent rangeland. In 1988, age structure differences were associated with density shifts in winter wheat between sample periods suggesting that older instars dispersed into the crop but younger instars remained in rangeland. In 1989 there was some partitioning of age classes between the two habitats, but no pattern emerged as in 1988. In 1990, significantly more older instars were collected in winter wheat than in rangeland. There were shifts in percentage density of the three grasshopper species in winter wheat but again no patterns emerged.

Disruption of mating for control of Oriental fruit moth [Grapholita molesta (Busck) (Lepidoptera: Tortricidae)] using Isomate M pheromone dispensers was tested from 1987 to 1990 in the Niagara Peninsula of Ontario. The effectiveness of pheromone was evaluated using virgin female-baited traps, synthetic pheromone-baited traps, and by inspecting samples of twigs and fruit for evidence of G. molesta damage. No males were caught in virgin female-baited traps placed in pheromone-treated plots. Synthetic pheromone-baited trap catches of male moths were reduced by 85–100%. Pheromone provided commercially acceptable control over two consecutive growing seasons at a commercial farm with a relatively low density G. molesta population. Pheromone did not provide commercially acceptable control at an experimental farm with a relatively high density G. molesta population. The incidence of capture of males in virgin female-baited traps, in synthetic pheromone-baited traps, and the incidence of damage to peach twigs by first- and second-generation G. molesta larvae could not be used to predict the incidence of damage to fruit at harvest. The results suggest that pheromone-mediated mating disruption may have potential as a method for controlling the Oriental fruit moth in orchards with relatively low density populations.

Morphology, distribution, and habitat data are presented for the known species of the oribatid mite genus Mycobates of America, north of Mexico. A revised generic diagnosis is given, and 11 new species are proposed and described on the basis of adults: M. altus, M. azaleos, M. beringianus, M. brevilamellatus, M. dryas, M. exigualis, M. hammerae, M. hylaeus, M. occidentalis, M. perates, and M. yukonensis. Three species proposed by Marie Hammer are redescribed, M. conitus, M. incurvatus, and M. punctatus, and a lectotype is designated for M. punctatus. Mycobates consimilis Hammer is considered a junior subjective synonym of M. sarekensis Trägårdh. Distribution maps are presented for these species and a diagnostic key is given to adults of species of Mycobates recorded from America, north of Mexico. Mycobates is species rich in dry arctic, subarctic, and alpine microhabitats of the Nearctic, Palearctic, and Neotropical regions. At temperate latitudes species often are arboreal, associated with moss and lichens on tree trunks.

Four species of Tychius have been introduced into North America from Europe: Tychius picirostris (Fabricius) (host plants: Trifolium spp.), widespread in North America; T. cuprifer (Panzer) (host plants: Trifolium spp., Teline monspessulana L.), known only from Maryland, USA; T. meliloti Stephens, new North American record (host plants: Melilotus spp.), known from scattered localities in Saskatchewan, Manitoba, Ontario, and Quebec, Canada; and T. stephensi Schoenherr (host plants: Trifolium spp.), widespread in North America. Keys to separate the species are presented.

The contact toxicities of 11 insecticides were determined with a Potter spray tower using adults of crucifer flea beetles (Coleoptera: Chrysomelidae) collected from three locations over a 3-year period. Flea beetles collected from an experimental farm at London, Ontario, where no insecticides had been used, were compared with those from canola-growing areas near Saskatoon, Saskatchewan, and Winnipeg, Manitoba. Lindane, in a seed dressing, is widely used in both Saskatchewan and Manitoba whereas carbofuran, as in-furrow granules, has been more heavily used in Manitoba than in Saskatchewan. The flea beetles from Winnipeg were significantly less susceptible to all three carbamates tested (carbofuran, carbaryl, oxamyl) than those from Saskatoon or London. Both the Winnipeg and Saskatoon flea beetles were significantly less susceptible to methamidophos than the London population but not to the other organophosphates, the organochlorine (endosulfan), or the pyrethroids that were tested. These differences may indicate resistance in the Manitoba population, but this low level would not affect the efficacy of the currently recommended insecticides. The results emphasize the need to develop control strategies that will minimize the chances that the level of resistance will increase.

Conioscinella zetterstedti Andersson, a Palaearctic chloropid fly with polymorphic wing reduction, is recorded for the first time from the Nearctic region. The known range of the species is also expanded in the Palaearctic region, with records from the Novosibirsk region of Russia. The male and female terminalia are described and illustrated. Although previously known only from supralittoral areas on the shores of the North and Baltic seas, collection data in the Nearctic and central Palaearctic regions indicate that C. zetterstedti may be abundant in various decay communities including peatlands, swamps, lake shore debris, mammal nests, forest leaf litter, and around the bases of vegetation.

Warren rootcollar weevil, Hylobius warreni Wood, is a pest of several conifer species and is distributed widely throughout the boreal forest in Canada. Literature on this weevil is reviewed and interpreted to provide comprehensive coverage of its ecology, behavior, and impacts, and the implications for its management. New information is provided to fill gaps in our knowledge of H. warreni. These include distribution and hosts, immature stages, sex ratios, and daily and seasonal activity patterns of adults. Sex ratios, abundance, longevity, and pedestrian dispersal behavior of adults within the forest and on trees are described from mark, release, and recapture studies conducted over several years using a newly designed interception trap. Daily trap captures are correlated with previous night temperatures and this relationship is a tool for predicting adult captures. Fecundity and oviposition behavior on the host tree are described from laboratory- and field-reared adults.

Population levels of H. warreni are compared across a variety of lodgepole pine stands in Alberta. Weevil numbers within forests are described in relation to tree size and age, depth of duff material around tree bases, and stand density. Analysis of weevil feeding scars distributed at the root collar base of mature pine stems were used to describe the likely temporal pattern of population abundance and change during stand development. Information supportive of this pattern is presented from surveys in young and mature stands.

A new method of assessing stands of lodgepole pine for suitability of habitat for H. warreni takes into account the cumulative nature of this weevil’s injury and reflects its temporal pattern of success in relation to stand conditions. The effects of a pre-commercial thinning treatment on H. warreni populations and its girdling injury were investigated in a 25-year-old lodgepole pine stand over an 8-year period. Compared with control plots, thinning treatment caused a 5-fold increase in weevil numbers per tree and increased the tree attack incidence by 2-fold, but resulted in an average 6% reduction in partial stem girdling of attacked trees. Information about the effects of various forest management practices on H. warreni abundance and survival is reviewed and areas requiring research are identified.

Neosymydobius neomexicanus sp.nov., N. peregrinus sp.nov., N. acutipilosus sp.nov., N. rumorosensis sp.nov., and N. paucisetosus sp.nov. are described and their relationship with other species is discussed. A lectotype of N. agrifoliae (Essig) was chosen from Essig’s type specimens. The taxonomic position of Neosymydobius is evaluated and a key for the identification of the presently known species is presented.

In Canada biological control of grasshoppers has been studied since the 1930s. Previous attempts at "classical" introductions have not been successful. Native parasitoids, especially sarcophagid flies, have a significant impact on grasshopper populations during certain times but the required conditions and regulatory potential are not understood. Sarcophagids, especially Kellymyia kellyi (Aldrich), and the mermithid nematodes Agamermis decaudate Cobb, Steiner, and Christie and Mermis subnigricans Cobb have some potential as inundative agents. Invertebrate predators appear to impact on egg and early-instar nymphal grasshoppers, and vertebrates, especially birds, help to regulate later instars and adults. The role of microbial pathogens in the population dynamics of grasshoppers in western Canada has long been recognized, particularly with regard to entomophthoran fungi. The possibility of utilizing the microsporidan Nosema locustae Canning for suppression of grasshopper populations has been postulated since the 1970s and field evaluations of its potential have been conducted in Saskatchewan and Alberta. More recently, considerable work, both basic and applied, has demonstrated the potential of various fungus isolates pathogenic to grasshoppers as both "classical" and inundative control agents. Entomopoxvirus isolates from grasshoppers also show potential as biological control agents of grasshoppers but this potential has yet to be investigated in field situations. It is clear, however, that no single microbial pathogen will be the panacea of grasshopper control. It is suggested that future biological control research focus on acquiring a better understanding of the requirements and quantitative effects of parasitoids and predators on grasshopper populations. Emphasis should also be placed on developing integrated pest management programs that utilize local natural enemies (nematodes and microorganisms) for inundative control during outbreaks.

Aspects of the life history of the aphid hyperparasitoid Asaphes vulgaris Walker, when reared on Aphidius nigripes Ashmead, were investigated under laboratory conditions. Longevity was significantly related to temperature and to the sex of adults. Female life span was about 4 months at 15 °C compared with 46 days at 25 °C; under the same conditions male longevity was 66 and 19 days, respectively. Females started to oviposit in aphid mummies upon eclosion and lifetime fecundity was high, reaching 1433 offspring. The sex ratio (proportion of males) was low early in reproductive life but rose sharply after several weeks. The implications of these results on the efficacy of A. nigripes in the potato agrosystem are discussed. It is suggested that high hyperparasitoid fecundity and longevity might play a role in reducing the impact of the primary parasitoid.

The leaf galler Diplolepis polita (Ashmead), known only from Rosa acicularis Lindl. west of the Rocky Mountains, is recorded for the first time on the introduced, urban shrub rose Rosa rugosa Thunb. Inquilines and parasitoids commonly kill over 90% of the inducers in populations of galls found in natural habitats, whereas 55% of the galls from the urban roses contained an inducer. Differences in component communities associated with galls on domestic and wild roses are likely indicative of a recently established population in an atypical habitat. Occurrence of D. polita on this new host also provides insight into the host specificity and vagility of cynipid wasps.

Larvae of the hemlock loopers Lambdina athasaria (Walker) from Vermont and L. fiscellaria (Guenée) from Maine are described for color, chaetotaxy, and gross morphology of the head, body, and legs. Body color varies from pale white-grey to dark green-brown with pigmented sclerotized bands. Head capsule color varies from pale grey-white to dark brown, with dark sclerotized spots of variable size. Many L. fiscellaria larvae are a lighter color than L. athasaria, but no consistent differences were found. The chaetotaxy of micro- and macrosetae conforms to the Geometridae, but the lack of detailed descriptions for other Lambdina species precludes a generic diagnosis. The homology of setae L and SV in Geometridae requires further resolution, particularly with respect to the presence or absence of L3 and SV2.

Diaeretiella rapae M'Intosh is a cosmopolitan parasitoid of several pest aphid species in agroecosystems, including the Russian what aphid, Diuraphis noxia (Mordvilko) (Mackauer and Stary 1967). In recent years, D. rapae has been imported into the United States from regions throughout the world for D. noxia classical biological control. Knowledge of the alternative hosts of D. rapae could be useful for identifying ecosystems into which the parasitoid could be released at times when D. noxia is absent. Over 30 aphid species are listed as hosts of D. rapae (Mackauer and Stary 1967). This host list, though comprehensive, is a compilation of information gathered from diverse, mostly unrelated sources, and does not necessarily depict the host range of any particular population. Host range differs among populations of some aphidiid species collected from different regions or from different hosts in the same region (Powell 1986). Thus, published host lists can be misleading if they are the sole source of information used to determine acceptable alternative hosts on which to release prospective candidates in classical biocontrol programs. The purpose of this study was to determine the relative suitability of several aphid species common to agricultural and associated non-agricultural ecosystems in the Great Plains as hosts for this Syrian D. rapae isolate in laboratory no-choice tests.