Nine species of Epidamaeus of subarctic western North America and extreme northeastern USSR are discussed. Six new species, Epidamaeus aborigensis, E. chukchi, E. floccosus, E. gilyarovi, E. koyukon and E. nasutus, are proposed; E. gibbofemoratus, E. hastatus and E. tenuissimus, previously described by Hammer, are redescribed.

Between 1973 and 1983 two newly introduced parasites, Agathis pumila (Ratz.) and Chrysocharis laricinellae (Ratz.), caused an increasing impact on populations of the larch casebearer, Coleophora laricella (Hbn.), as measured by percentage parasitism based on adult emergence and the associated mortality of hosts that did not produce parasites. Total impact of the parasites cannot be measured by adult emergence alone but must include parasite-killed hosts from which no parasites emerged. Nevertheless, trends in parasite effectiveness are represented by percentages based solely on adult emergence. Only 53.1% of the adult A. pumila successfully emerged in 1983 samples. Furthermore, the number of emerged plus non-emerged A. pumila was only 53.3% of the number expected based on previous samples of that same generation. This mortality of A. pumila took place even in the absence of significant populations of C. laricinellae, indicating that although C. laricinellae may cause some reduction in parasitism by A. pumila, other factors are also responsible.

In a recent monograph of the plant bugs of the prairie provinces (Kelton 1980), I stated that the subfamily Cylapinae did not occur in the prairie provinces. However, collections in 1982 and 1983 in Manitoba and Alberta produced specimens of Fulvius imbecilis (Say). This is the first record of this species in Canada. Additional records for Canada are given for F. slateri Wheeler, imbecilis is illustrated, and a key to separate them is provided.

Incidence of parasitism by Pteromalus venustus Walker in populations of the alfalfa leafcutter bee, Megachile rotundata (F.), in western Canada from 1976 to 1983 was found to average ca. 1%. An average of 17.4 parasite adults emerged from each host cocoon and the ratio of males to females was 1:1. Temperature-dependent development and survival at 8 constant temperatures are described. The range of temperatures for greatest survival of the parasite (30–32 °C) coincided with the recommended incubation temperatures for cocoons of the leafcutter bee. Development data fitted a 4-parameter development model. Linear regression of development rate versus temperature provided estimates of base temperature and development time in degree-days for the egg, larval, pupal, and combined stages.

Thirty-four species of insects associated with Scolytus multistriatus (Marsham) were reared or collected from several species of elm collected throughout California. Few of these species occurred in large numbers and many of their ecological roles in this subcortical habitat are unknown. Predators were uncommon; only 6 species of parasitic Hymenoptera were reared, 3 of which were not previously known from California. One, Dendrosoter protuberans (Nees), had previously been released for biological control of S. multistriatus only as far west as Colorado. The most abundant insect associate reared from northern California, Cheiropachus quadrum (F.), exhibited a maximum percentage parasitism of 2%. Seven species of mites, including 2 new species, were also collected in association with S. multistriatus.

The dogwood borer, Synanthedon scitula (Harris), is a relatively new pest problem on apples. Larvae feed principally in burr knots on the above-ground portion of clonal rootstocks. According to a survey of 33 orchards on dwarf or semidwarf apple root-stocks, about 70% of the trees had burr knots. The tendency to develop burr knots was similar among the rootstocks examined in this survey. The proportion of trees infested with dogwood borer in an orchard ranged from 0 to 100% and averaged 30%. The dogwood borer overwinters in the larval stage (2nd to 6th instar) and pupates in the feeding tunnel. Emergence and pheromone-trap records indicate 1 generation a year. In western New York, adults begin to emerge in mid-June, peak in mid-July, and continue to emerge through September. In several tests conducted over a 3-year period, chlorpyrifos at 180 g/100 L provided the most consistent control. At this rate a single spray timed to first or peak egg hatch was as effective as 2 sprays. Latex paint applied by brush to the trunk at the beginning of the oviposition period also reduced the infestation. In established plantings, dogwood borer can also be controlled by berming with soil up to the graft union to prevent access to burr knots. Destroying burr knots chemically with naphthalene acetic acid will not eliminate an infestation and may invite other borer problems.

Four aggregation sites for male Cephenemyia trompe Modeer were studied in the Kluane Game Sanctuary, southwest Yukon. All sites were well-defined topographical peaks at considerable distances (usually greater than 1 km) from one another. Males rested on the rocks and vegetation and individuals made frequent flights to investigate passing insects, presumably in search of a female. Male flies were active at the sites on element days; activity was a function of both temperature and light intensity. Flies remained at a particular site at least throughout the day but did not defend individual territories.

Observations on Malus domestica (Borkh) in central Ontario between 1981 and 1984 revealed that dogwood borer (Synanthedon scitula Harris) larval feeding was primarily associated with burr knots on the above-ground portion of apple rootstocks. Trunk injuries also served as sites of entry. Monitoring with pheromones indicated moth emergence occurred from late June until early August with peak activity occurring near the middle of July. Control of the dogwood borer on apple was obtained with 2 trunk drench sprays of dimethoate, fenvalerate, permethrin plus oil, endosulfan, parathion, chlorpyrifos, or lindane when applied during the period of adult flight activity.

Douglas-fir cones were collected from 17 seed orchards in California, Oregon, and Washington in the fall of 1983. Cones were completely dissected and seed losses ascribed to the Douglas-fir cone gall midge (Contarinia oregonensis (Foote)), the Douglas-fir seed chalcid (Megastigmus spermotrophus (Wachtl)), the Douglas-fir cone moth (Barbara colfaxiana (Kearfott)), and the fir coneworm (Dioryctria abietivorella (Groté)). There appear to be great differences between orchards, but overall C. oregonensis and M. spermotrophus collectively destroyed approximately 70% of the filled seed. Physiographic province significantly (P<0.05) explained variation in damage by all insect species between seed orchards. In general, damage by all species increased from northern provinces to southern mountainous provinces. Damage by C. oregonensis and B. colfaxiana appeared to be related to land use or management factors, as well.

A new species of Hyposoter Foerster from western North America is described based on features of the adult, final-instar cephalic structure, cocoon, and biology. Hyposoter masoni n. sp. is a common parasite of the Douglas-fir tussock moth, Orgyia pseudotsugata.

Searching for adult coccinellids in large cages placed over sections of strawberry fields produced an average of 10 times as many coccinellids per metre of row as a relative method of sampling. Methods of converting relative indices to absolute indices of abundance were found. Results suggest that the frequently observed slow increase in abundance of aphid predators in response to increasing aphid abundance may be an artifact resulting from using relative indices of abundance that make no correction for the effects of hunger on predator activity. Calibrating the samples shows that numbers of adult coccinellids follow the trend of aphid abundance closely enough that coccinellid numbers may be predictable.

Populations of Scolytus multistriatus (Marsham) from two areas of California were sampled in 1979 to investigate various factors influencing mortality. English-elm bolts (Ulmus procera Salisb.) ranging between 2.0 and 12.9 cm in diameter yielded mean mortalities from 49.1 to 86.0%. Mortality was highly correlated with egg density for branch samples from 7.0 to 12.9 cm in diameter. The minimum acceptable elm-branch diameter (2.8 cm) was attacked only during the first sampling period (mid-May to mid-June). Branch diameter, and therefore bark thickness, demonstrated a strong positive relationship with the density of S. multistriatus eggs, attacks, gallery lengths, and emerged adults. Gallery length density was positively correlated with attack density. At low attack densities in small-diameter branches, mean gallery lengths were shorter.

A standard test for the larvicidal activity of Bacillus thuringiensis (B.t.) against the larvae of the sunflower moth Homoeosoma electellum (Hulst) has been developed. Bioassay parameters investigated include diet preparation, concentration of B.t., effect of formaldehyde, and method of pathogen incorporation in diet. The LC50 for seconded third-instar larvae is 1.24 μg of Dipel® WP ml−1 or 19.8 IU B.t. ml−1 pathogen-incorporated diet. Layering of a pathogen-suspension upon the surface of the diet was not a reliable bioassay technique for H. electellum. The addition of formaldehyde in the diet reduced the slope of the dose–mortality curve but did not change the LC50.

A method of rearing Paraphlepsius irroratus (Say) under artificial conditions was developed by using a leguminous plant species as the oviposition host and a gramineous species as the food plant for nymphs. Nymphs completed their development on all 10 gramineous species tested. Total time for completion of the 5 nymphal instars ranged from 31.8 to 59.2 days, depending on the plant species used. With the exception of Alopecurus pratensis, all monocotyledonous species tested were found to be suitable food plants for nymphs, allowing 50% or more of the insects to survive for 3 weeks or more. Only 5 dicotyledonous species supported a similar survival level of nymphs. Adult survival remained above the 50% level on Apium graveolans var. dulce, 6 members of the Leguminosae, and all members of Composite with the exception of Callistephus chinensis. Survival of adult leafhoppers on monocotyledons was relatively high after 1 week but considerable mortality followed longer confinement. Although nymphs emerged from eggs laid on a wide range of plant species, the numbers recorded on monocotyledons suggest that monocots are important as oviposition hosts for P. irroratus in nature.

Predispersal seed predation of Cirsium arvense (L.) Scop. (Asteraceae) by Orellia ruficauda (Fabr.) (Diptera: Tephritidae) occurs in about 20–85% of the seed heads and the proportion of damaged seeds per attacked head averages 20–80% depending on geographical location and sampling date. Microscopic studies of damaged seeds were performed. Although the impact of this seed predator is not severe, it may be an important factor in the population regulation of the weed.

The numbers of larvae and pupae of the gypsy moth, Lymantria dispar L., were monitored in southwestern Quebec from June through August 1980 at 13 sites. In 10 sites, the proportion of male pupae was significantly different from an expected proportion of 0.5. Linear-regression analyses of the proportion of male pupae on larval density showed a significant increase in the number of male pupae with increasing larval density. Changes in the sex ratio could be an important indicator of the dynamic state of a population, and should be considered in modeling the population dynamics of gypsy moth.

Predatory arthropods were sampled in high-maintenance Kentucky bluegrass lawns (lawns under commercial lawn care), low-maintenance Kentucky bluegrass lawns (under minimal care), and low-maintenance tall-fescue lawns. In general, tall fescue supported fewer predators than Kentucky bluegrass, specifically the families Erigon-idae, Linyphiidae, and Carabidae. Populations of Erigonidae, Linyphiidae, and Carabidae were lower in high-maintenance bluegrass than in low-maintenance bluegrass. The carabids Amara cupreolata Putzeys, Agonum punctiformum (Say), and Harpalus (Pseudopkonus) spp., and a staphylinid, Philonthus sp., were particularly uncommon in high-maintenance sites. Hierarchical classification of sites suggested that the structure of the staphylinid and carabid communities differs in tall fescue and Kentucky bluegrass turf, and differs in high- and low-maintenance bluegrass.

During 2 field seasons, Coccinellidae (primarily Coccinella transversoguttata richardsoni, Coleomegilla maculata, Hippodamia convergens, H. tridecimpunctata, and H. glacialis) were the most abundant predators on potato hybrids (Solanum tuberosum × S. berthaultii, F3) with various densities of glandular pubescence. Highly pubescent clones had the highest percentage of predator eggs, while clones with the lowest trichome densities had the highest percentages of immature and adult predators. By comparison, high numbers of aphid parasitoid mummies (primarily Aphidius and Praon spp.) occurred on clones with moderate to high densities of glandular pubescence. During both years, predators and parasitoids were most abundant in late July and August.

Emergence from hibernacula of 2nd instars of Choristoneura occidentalis was more variable but later than that of C. retiniana. However, early-instar development was faster in C. occidentalis and compensated for the difference in emergence times so that both species entered the 6th instar simultaneously. There were no species-related differences in development beyond the 6th instar. Though they have different resource-tracking patterns early in their life cycle, temporal isolation between these species is unlikely. No developmental morphs were found in either species but there were several instances where individuals that developed at an increased (or decreased) rate in one stage developed slower (or faster) than the mean rate in a substantial stage. Negative correlations between development times were indicative of this. These correlations reduced variation in adult eclosion times induced by extended spring emergence and are indicative of homeostasis in development within populations. Negative correlation coefficients between development periods were more common in C. occidentalis, which also had the more variable spring-emergence pattern. Hybrids were intermediate in almost all development traits.

The winter survival of artificial and natural infestations of pupae of the bertha armyworm, Mamestra configurata Walker, are assessed in relation to soil temperature and snow depth. The results are discussed in relation to the hypothesis that winter mortality affects the spatial distribution and timing of outbreaks of this pest. Pupae did not survive a Manitoba winter in snow-free field plots, but 55% survived in plots with 5 or 10 cm of snow. Pupal survival in the plots was estimated accurately from daily soil temperatures using a computer simulation model, confirming that natural soil-temperature regimes can affect pupal survival. Based on the model, an equation was derived to relate pupal survival to the number of winter days with soil temperatures of −10°C or less. For natural populations in canola fields, the model, in conjunction with a model that estimated soil temperatures from standard meteorological data, could estimate the observed survivals. However, the estimates were sensitive to estimated snow cover and the measurements of snow cover in the fields were incomplete. There was a significant negative relationship between mortality and snow depth measured at the end of January up to about 20 cm. The sensitivity of soil temperature and therefore pupal survival to small changes in snow depth makes it difficult to predict pupal survival for large areas. Although the distribution of outbreaks of bertha armyworm coincided with the areas of the canola-growing region where winter soil temperatures were highest, the summers when outbreaks occurred were not preceded by winters with high soil temperatures, nor were summers without outbreaks associated with low soil temperatures during the preceding winters. Winter soil temperatures apparently affected the spatial distribution of outbreaks, but variation in pupal survival due to winter soil temperatures did not, by itself, initiate or terminate bertha-army worm outbreaks.