Spruce beetles (D. rufipennis) from a population homogeneous with respect to population quality were subjected to different degrees of competition at corresponding stages of their reproductive cycles by varying the spacing of individuals and by varying the time of introduction of individuals into the competitive environment. Competition effects increase with gallery accumulation, as suggested in previous studies, and result in subsequent reduction of gallery production and oviposition. Increase in individual beetle quality, however, confers increased powers of resistance to the competition effects. Initial egg-free length is an unsuitable attribute for comparisons of populations. Expression of reproductive efficiency is a dynamic population characteristic which varies over the reproductive cycle, and which may be readily estimated by measurement of yolk deposition rate. For comparing populations, such measurements would be more valuable when carried out before the onset of competition effects. Individuals with the highest quality at the start of the egg-production cycle exhibit the highest reproductive efficiency as conditions change.

Treatment of a pond with a 0.5% sand granule formulation of SIR-8514 yielded a maximum, concentration (4.6 ppb) by 1 day following the application. No residues were detected in the pond sediment and by 28 days posttreatment residues were not found at any depth of the water column. Emergence of pestiferous dipterans was reduced by >99%, and planktonic arthropod populations decreased by >90% following the treatment. Planktonic rotifers and dinoflagellates, and benthic organisms were less severely affected.

Bluegill sunfish (Lepomis macrochirus Rafinesque) and mosquitofish (Gambusia affinis Baird and Girard) accumulated maximum concentrations (ca. 400 ppb) of SIR-8514 by 2 days posttreatment. No residues in fish were detected by 28 days posttreatment, and no fish mortality was observed.

The longevity and age specific fecundity, as well as the sex ratio of the progeny, were obtained for Aphidius nigripes Ashmead females given access to the five developmental stages of the potato aphid, Macrosiphum euphorbiae (Thomas). Neither female longevity nor fecundity, as measured by the total number of aphids parasitized, were significantly different for the various host stages. The percentage of females in the progeny decreased as the female parasite aged, and the overall sex ratio of progeny was significantly affected by the host stage attacked although no direct relationship with host size was evident. However in a separate experiment where parasitism was controlled (females not permitted to attack more than 10 hosts per day), the host stage (size) significantly affected the sex ratio of progeny, with more females emerging from larger than smaller hosts.

These data indicate that all developmental stages of M. euphorbiae, when presented separately, are suitable to A. nigripes.

A technique is presented that requires no direct measurement of gallery length to estimate the total gallery length. Required to obtain the estimate are: (1) an appropriate model for time of year, sample period, and host, (2) tree diameter at breast height, (3) length of infested bole, (4) total tree height, and (5) inner bark thickness. The technique is accurate, less time consuming, and less expensive than direct estimation techniques.

The free fatty acid composition of the southern pine beetle, Dendroctonus frontalis Zimmermann, and associated bark beetles was determined by gas-liquid chromatography. The lipid composition of several species of hymenopterous parasites matched the bark beetle hosts from which they were reared. Lipids from field collected parasites were compared with the lipid composition of possible bark beetle hosts to determine host of origin. Parasites ovipositing on a host were usually found to have a lipid composition matching that host. Approximately 20% of the parasites that were observed attempting to parasitize the southern pine beetle apparently developed on other bark beetle hosts.

A serological technique, the precipitin test, was examined as a method for determining the feeding habits of the spider Pardosa sternalis Thorell (Araneae: Lycosidae). Radial immunodiffusion responses were significantly influenced by quantity of prey consumed, the time elapsed between spider feeding and serological analysis, and the temperature at which spiders were maintained after feeding. Maximum antigen detection time after feeding was 150–200 h for spiders fed varying quantities of prey and held at 25°C and over 400 h for those held at 4°C. Ouchterlony double diffusion tests indicated that although two congeneric prey species could be distinguished from one another, significant cross-reactivity between the two was observed. No such cross-reactivity occurred between more distantly related prey species. The feasibility for utilizing precipitin analyses in field studies of predator–prey relationships is discussed.

Ten species of black flies were collected from the Souris River, Manitoba between April 1977 and October 1978. Adults of Simulium luggeri Nicholson and Mickel, Simulium meridionale Riley, Simulium venustum Say, Simulium verecundum Stone and Jamnback, and Simulium johannseni johannseni (Hart) were collected feeding on livestock and humans, and are well known pest species. Simulium vittatum Zetterstedt was the most abundant species, but was not a pest on man or domestic animals. Simulium tuberosum (Lundström) and Simulium johannseni duplex Shewell and Fredeen were the least abundant species. Simulium j. johannseni, S. j. duplex, S. venustum, S. verecundum, S. tuberosum, and Cnephia dacotensis (Dyar and Shannon) appeared to be univoltine species while S. luggeri, S. meridionale, Simulium decorum Walker, and S. vittatum were multivoltine in the Souris River.

An evaluation of cone, plate, rope, and wire cage sampling devices for black fly larvae and pupae indicated that cone samplers provided a more representative sample for population assessment.

In a black fly control program, of the Souris River, Manitoba two separate larvicide treatments in spring may be necessary. In the case of two treatments, the first should be aimed at late instar larvae of S. j. johannseni, S. venustum, and S. verecundum. Since the majority of S. luggeri and S. meridionale would be in the egg stage at this time, a second treatment, 10–14 days later, would be necessary to control late instar larvae of these species.

Male release-recapture experiments show that under natural photoperiod there is no cross attractancy between species of the sympatric pairs E. declarata and E. campestris or E. declarata and E. rockburnei, but that there is between the parapatric pair, E. campestris and E. rockburnei. When the calling periods of E. declarata and E. campestris females are synchronized by photoperiod manipulation there is cross attraction between these two species as well. However, in mating discrimination tests between E. declarata and E. campestris the normally strong bias against interspecific mating is only partially overcome by synchronizing mating activity rhythms. The residual tendency for conspecific mating is more likely due to imperfect synchronization of mating rhythms or differences in close range courtship behavior than to differences in attraction pheromone. Males of all three species are attracted to the same synthetic attractants. The results are consistent with the hypothesis that the attraction pheromones of the three species in the declarata group are very similar and are unlikely to play a major role in reproductive isolation, which is probably effected primarily by differences in circadian rhythms of mating activity.

The three closely related species of Euxoa cutworm moths comprising the declarata group gave identical male antennal responses to synthetic C10 to C18 alkenyl derivatives. An extract and a solution of the volatile emissions from E. campestris females when fractionated by gas chromatography yielded a single EAG-active fraction whose elution corresponded to a C10 acetate. The active component was assigned (Z)-5-decenyl acetate based on its mass spectrum and capillary GC retention time and the EAG responses of campestris males to isomeric decenyl acetates. Field trials demonstrated (Z)-5-decenyl acetate attracted males of all three species although it was not as attractive as live females. Attraction was suppressed by (Z)-5-dodecenyl actate, (Z)-7-dodecenyl alcohol, and (Z)-7-dodecenyl acetate.

Vapour degreasing and cleaning of entomological specimens proved to be a viable alternative to standard methods. Defined change in colour upon degreasing clearly portrayed the effectiveness of this new technique.

Frequently descriptive entomology suffers from a lack of precise data on specimen colour. Since colour is rarely defined and since an effective technique is available, the authors suggest that greater consideration be given colour analysis. A simple procedure is outlined in relation to colour analysis of specimens undergoing degreasing.

The adult stage of Drunella allegheniensis (Traver) is described for the first time. Characters separating it from the closely related D. tuberculata (Morgan) are summarized, and the existing taxonomic key to the group is modified to include D. allegheniensis. Other species of Ephemeroptera associated with D. allegheniensis are reported along with observations on its biology.

The first outbreak of Dutch elm disease in Manitoba was recorded in 1975 in Brandon, Selkirk, and Winnipeg (Hildahl 1977). The primary vector of the disease in Canada is the native elm bark beetle, Hylurgopinus rufipes (Eichh.). The smaller European elm bark beetle, Scolytus multistriatus (Marsh.), is considered the primary vector in most of the United States. In Canada, the latter species occurs throughout most of southern Ontario, parts of south-central Quebec, and has been recorded in New Bmnswick (Sterner et al. 1976).