First instar larvae of five spring Aedes spp. mosquitoes survived for at least 25 days beneath moderately thick ice (4.5 cm) in an open field habitat. While survival in the open field was in excess of 85%, larvae inhabiting a nearby deciduous woodland pool suffered 100% mortality within 25 days. Dissolved oxygen levels in the woodland pool fell drastically over the period of ice-cover indicating a trend toward an anaerobic condition which likely contributed to larval mortality.

Evidence for secondary attraction in the western balsam bark beetle, Dryocoetes confusus Swaine, was obtained in laboratory bioassays and field experiments. Both sexes showed positive responses to volatiles of the host tree, Abies lasiocarpa (Hook.) Nutt., indicating that primary attraction is probably important in host selection by this species. Male beetles initiated attack and within 6 h produced an aggregation pheromone(s), which was present in frass and in pentane extracts of the abdomens of males excised from logs. Both sexes responded to the pheromone. Abdominal extract of unmated males which had bored into host bark for 14 days was still attractive. Pheromone production was induced by exposing males to host resin volatiles. Mating had no effect on male attractiveness, but induced females to produce an antiaggregation pheromone which, in laboratory bioassays, at least partially inhibited response to male attractant. The attractive volatiles from male-infested logs were successfully captured on Porapak Q®. The development of laboratory bioassay and pheromone extraction techniques indicates that a pheromone isolation program is feasible.

Females of a European parasite, Microctonus bicolor Wesm. tested with adults of crucifer-infesting flea beetles from Manitoba, oviposited readily in Phyllotreta striolata (F.) and occasionally in Phyllotreta cruciferae (Goeze), but not in Psylliodes punctulata Melsh. Immature parasites developed and emerged from both P. striolata and P. cruciferae. M. bicolor is unlikely to provide economic control of P. cruciferae, which is the most important of the rapeseed-infesting flea beetles in the southern part of the prairie provinces. Further releases of M. bicolor should be in more northerly rapeseed-growing areas where there are higher population densities of P. striolata than at the original release site in southern Manitoba.

Laboratory studies of the mean weights of initial eggs (Ei) of the spruce budworm, Choristoneura fumiferana (Clem.), show that this value is determined by the genetic constitution of the female moth and is relatively independent of environmental control. Dietary differences experienced by the female during larval development, and originating from different hosts or from reduced nutrient levels in artificial diets, did not affect Ei values; however, depletion of nutrients sufficient to reduce fertility greatly did reduce Ei. Temperature conditions during the ultimate larval and pupal stages influence Ei values which vary inversely. Mean egg weights are strongly heritable and are readily selected for, thereby demonstrating the presence of strong genetic control.

Hollow fibers containing synthetic pheromone (Z-6-heneicosen-11-one) were applied by helicopter to six plots of about 8 ha each. Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), had reached such high population levels on the plots that trees in some areas were completely defoliated. Reproduction of the moths was reduced 71 and 81%, respectively, at dosages of 8 and 25 g of pheromone/ha relative to untreated control plots.

An analysis of the times to emergence in three sparse populations of Choristoneura spp. in western North America indicates that there was considerable variation in the calculated threshold of development among populations. Also, the number of heat units required to effect the emergence of any specified proportion of the population varied considerably among populations. The pattern of intra-population variation in times to emergence is such that the within-family variation was much larger than the among-family variation in the two populations from areas in which white fir is the only host. In the other population, from an area with a mixed stand of Douglas-fir and white fir, the pattern is reversed. This pattern remains even after an accounting is made for the parental host and larval color morph. It is hypothesized that the pattern of variation in the times to emergence may be due to the presence, in the latter population, of physiological morphs which cannot be recognized either by their appearance or their host of origin. These results have clear implications for pest management procedures which attempt to schedule activities related to the emergence of these insects in the spring.

The influence of sex ratio on the reproductive ability of the tobacco hornworm, Manduca sexta, was examined under laboratory controlled conditions. The optimum sex ratio was found to be 0.50 (F/T) displaying the highest rate of oviposition and egg production. The fertility of the eggs laid was linearly dependent on the number of males present in each ratio. Unmated females lived longer and began oviposition later than mated females. The percentage of the total egg production retained by the females was highest for the 0.17 and 0.83 ratios and may be attributed to a stress-related impairment of reproductive behaviour.

Cornicle length measuremetns of Acyrthosiphon pisum (Harris) nymphs reared in the laboratory were instar-specific and unaffected by rearing temperature. A multimodal analysis of cornicle lengths of field-collected aphids clearly detected four distribution peaks (i.e., instars) in five different field populations, and there was generaaly little overlap between successive instar distributions. However, third and fourth instars in the spring field sample could not be separated accurately due to the shorter cornicle length of nymphs that developed from overwintered eggs. Cornicle length proved to be a useful criterion for separating virginoparous A. pisum instars in samples collected in southern Wisconsin.

The timing of diapause termination and the thermal characteristics of postdiapause development were compared in six Ontario populations of the spotted tentiform leafminer, Phyllonorycter blancardella (Fabr.). The populations studied were from the major apple growing areas which are located in four climatically different zones. Pupae of all populations collected in the fall and stored under simulated overwintering conditions had terminated diapause by the end of January. Pupae overwintering under natural conditions had also terminated diapause by this time. Significant population differences occurred in the postdiapause developmental threshold (t0) and thermal constant (K). Simulating postdiapause development and emergence of the six populations using the 1981 temperature records from one location resulted in a 9-day difference between the earliest and latest mean emergence times. The implications of these results for pest management are discussed.

Cohorts of instar I larvae of the Douglas-fir tussock moth, Orgyia pseudotsugata, were stocked on branches of white fir, Abies concolor. Branches were either exposed naturally over drop-trays or protected with cages of nylon netting. Only 8.7% of the larvae in exposed cohorts survived to pupate, compared with 68.0% survival in caged cohorts where dispersal and predation were prevented. Losses from the exposed cohorts were caused mostly by arthropod predation, disappearance, and non-replaced dispersal. Disappearance of early larvae was attributed primarily to predation by spiders and insects while disappearance of late larvae was suspected to be due mostly to bird predation. In an analysis of k-values, actual or suspected predation accounted for 47.2% and dispersal 40.5% of the total loss.

A process-oriented model was developed to describe the oviposition of the spruce budworm, Choristoneura fumiferana (Clem.), on an individual and a population basis. The model simulates the effects of temperature on female longevity, oogenesis, and oviposition. The model is structured for ease of incorporation of additional processes such as emigration, immigration, mating, and other behavioral reductions in oviposition activity. Simulation results, at both the individual and the population levels, are compared with laboratory and field data. This model is an element of a model of spruce budworm biology currently under development but, by itself, can be used to study the effects of temperature and dispersal on the fecundity of spruce budworm populations.

A suction trap operating 1.4 m above ground and sticky traps arranged from ground level to 7 m were used to collect flea beetles during 1979–1982. The suction trap showed a peak in flight activity for Phyllotreta striolata (F.) in late April and May, but caught few beetles later in the season. The same trap showed that Phyllotreta cruciferae (Goeze) commenced flying a few days later than P. striolata, but continued to fly through the summer. The highest catch of P. cruciferae occurred in late August and early September. Prior to early June more flea beetles were caught on sticky traps at 1 and 2 m than on traps at ground level or 0.5 m. Subsequently more were caught at the two lower elevations. Beetles were captured on sticky traps up to the highest trapping height of 7 m throughout the growing season. These data suggest that the average flight elevation and level of flight activity are highest until the beginning of June for both species and then drop, and that P. cruciferae usually flies more actively and at higher elevations than P. striolata.

Overwintered P. cruciferae flew only when daily maximum temperatures exceeded 14 °C. The new generation of adults was captured flying in August and September when daily maximum temperatures were as low as 4.7 °C. Throughout the season, the catch in a suction trap was negatively correlated with average wind speed.

Given the extended flight period of P. cruciferae, late seeding of canola would not prevent invasion of the crop by this pest. Day to day variation in beetle catches by sticky traps or a suction trap, and trap to trap variation for sticky traps was high. Therefore, such traps would not provide sufficiently precise estimates of flea beetle densities prior to seeding to permit farmers to determine whether a field requires a seed treatment.

Blethisa inexspectata is described as new from one male specimen from Alaska; it is the sister species of B. julii LeConte. The phylogeny and biogeography of Blethisa Bonelli is discussed, and a key to all known species of Blethisa is given. Blethisa kaszabi Jedlička 1967 is placed in synonymy with B. tuberculata Motschulsky 1846.

Directional cone-orifice traps were suitable for monitoring population densities of five Lepidoptera species, provided the captured moths were removed from the traps on a regular basis of at least once a week throughout the flight period. Omni-directional traps with circular screen barriers in the entrance area and a slow-release insecticide in the receiver to kill the captured moths functioned well over extended periods of unattended use. These traps would be useful for monitoring and mass trapping purposes. Similar traps without the circular screen barriers were less efficient but, due to their simplicity, they would also be suitable for monitoring purposes. The optimum quantity of pheromone per dispenser was the same for the directional cone-orifice and omni-directional traps.

Several parasites were surveyed for their ability to develop to pupation in virus-infected hosts. The tachinid Compsilura concinnata (Meigen), the ichneumonids Campoletis sonorensis (Cameron) and Hyposoter exiguae (Viereck), and the braconid Cotesia marginiventris (Cresson) developed to pupation in the armyworm, Pseudaletia unipuncta (Haworth), infected with either the Hawaiian strain of granulosis virus (HGV) or the hypertrophy strain of nuclear polyhedrosis virus (HNPV). The braconid Chelonus insularis Cresson died after its HGV- or HNPV-infected host P. unipuncta died. On the other hand, the braconid Glyptapanteles militaris (Walsh) died in HNPV-infected P. unipuncta before the host died. Some of these parasites had tissues that were melanized and some were encapsulated by the host. The ichneumonid H. exiguae and the braconids Chelonus insularis and Cotesia marginiventris developed to pupation in HGV-infected Spodoptera exigua (Hübner). In some cases, developmental time of parasites in virus-infected hosts was longer than in control hosts.

Linear regression analysis was used to estimate the developmental threshold, t0, and thermal constant, K, for all preadult stages of two laboratory colonies of the mosquito Toxorhynchites rutilus septentrionalis (Dyar and Knab). The colonies originated from Newark, Delaware and Lake Charles, Louisiana. The physiological and ecological significance of the within- and the between-population differences in the slopes of the regressions,t0's and K's, are discussed.

The multiple funnel trap, an efficient, collapsible, non-sticky trap for scolytid beetles, consists of a series of vertically aligned funnels with a collecting jar at the bottom. The trap compared favorably with sticky traps and Scandinavian drainpipe traps for three species of ambrosia beetles and the mountain pine beetle. Minimum maintenance required for this trap allows for high efficiency in pheromone-based research, survey, and mass trapping of scolytid beetles.

An equation is presented for the determination of sample sizes needed to estimate with a given precision the larval population density of spruce budworm on balsam fir and white spruce branch tips in Ontario. This equation is primarily applicable to low densities, but is valid to a density of 50 larvae/branch tip. The distribution of budworm larvae at densities below 0.1/branch tip is nearly random, and is aggregated at higher densities. Their distribution is the same on the two host species.

Empoides Vilbaste, 1968 is synonymized with Empoa Fitch, 1851, which is treated as a subgenus of Typhlocyba Germar, 1833, with 9 new combinations. The male genitalia are illustrated. The gillettei complex, consisting of 14 Nearctic species with identical male genitalia, is analyzed using 90 series taken on identified hosts. T. bella and T. unifasciata n. spp. are described from eastern Canada, and three new synonymies based on colour variation are presented: Empoa acericola Christian, 1953 and E. caryata Christian, 1953 = E. gillettei Van Duzee, 1917, and E. elmata Christian, 1953 = T. saffrana McAtee, 1926. A key to the species of the gillettei complex is included.

The arthropod fauna of New Brunswick potato fields was surveyed using pitfalls, yellow pan traps, ground cloths, and sweepnets. Of the more than 560 species or group-species identified during the 3-year study, at least 80% were transient ones indicating a loosely structured community of insects. Terricolous arthropods typically had a lower number of species and a more even distribution than aerial arthropods but a similar index of diversity. The proportion of parasitic and predatory species was high suggesting a potential for the use of native biological control techniques in potato pest management programs.