The thickness of the wall of the puparium of the apple maggot, Rhagoletis pomonella (Walsh), increased as the puparium aged. The force required to pierce the wall of the puparium also increased with age, and this relationship was best described by a cubic polynomial. Increasing thickness and hardness of the wall of the puparium will likely influence the efficacy of the parasite Phygadeuon wiesmanni Sachtl.

Rhadiurgus variabilis (Zetterstedt 1838), a robber fly described from Europe, and Nigrasilus nitidifacies Hine 1908, described from North America, are newly synonymized. Lectotypes are designated for Asilus variabilis Zetterstedt and N. nitidifacies Hine. Some new descriptive material, including measurements and colour data, is given for five geographical regions: Europe, Eastern Siberia, Alaska/Yukon, Western Cordillera, and Boreal North America. Illustrations of male and female genitalia are presented. The species’ range is clarified and ecological data are summarized. Rhadiurgus variabilis inhabits northern and mountain forests from Scotland eastward to Labrador; it is one of the world’s most northerly ranging robber flies. Variation in the species includes an increasing proportion of dark body setae in individuals from Eurasia eastward through North America.

I examined the relative feeding preferences of five carabid beetle species for terrestrial gastropod prey. Scaphinotus marginatus Fischer, thought to be a snail specialist, discriminated among seven species of potential prey by size and species, with the slug Deroceras reticulatum (Müller) being the most preferred. Scaphinotus marginatus appears to use its elongated and narrowed mouthparts, head, and thorax to prey upon terrestrial snails without having to crush their shells. The relative feeding preferences of four pterostichine generalist predators (Pterostichus adstrictus Eschscholtz, P. pensylvanicus LeConte, P. protractus LeConte, and P. surgens LeConte) for two species of small snails [Discus cronkhitei (Newcomb) and Euconulus fulvus (Müller)] also were examined. Although all four carabids ate E. fulvus in varying proportions, only P. protractus consumed D. cronkhitei. I suggest that snail shell thickness and differing feeding preferences affect which snail species are eaten by these pterostichines.

The daily patterns of activity of females of the orange wheat blossom midge, Sitodiplosis mosellana (Géhin), were observed in controlled laboratory conditions and in field conditions in eastern Saskatchewan in mid-July 1986 and 1987. In the field, during the daytime, females rested on stems of wheat plants within 30 cm of the ground and, at approximately 2000 hours CST, flew up to wheat heads. Most oviposition took place between 2000 and 2145 hours (or 75 min before, to 30 min after, sunset). Toward the end of the oviposition period, females were frequently seen drinking dew from wheat heads. On some evenings, females migrated down from the heads following oviposition, but on more than half of the evenings they remained on the heads until early morning. However, they never moved down to the low level they occupied during the day until the next morning, when the migration was usually complete by 0900–1000 hours. Light intensity appeared to regulate the vertical migration of females. Cloudy conditions may allow an earlier onset of oviposition. Flight was limited to air temperatures above 14–15 °C and oviposition to temperatures above 10–11 °C. Wind speeds of 10 km per h or more and rain occasionally limited activity. In the laboratory, oviposition activity occurred almost exclusively during the scotophase, mainly in the first 2 h. Mean total fecundity was 83.6 ± 10.9 (±SE) eggs, and mean longevity was 6.6 ± 0.6 days. No oviposition took place on the 1st night, and the greatest mean daily fecundity occurred on the 3rd night.

Pterin accumulation in response to temperature and time was studied in male and female stable flies Stomoxys calcitrans (L.). Pterins accumulated as a function of temperature integrated over time. The threshold for pterin accumulation was estimated at 6.5 °C. The relationship between pterin content (RF/mm head capsule width) and accumulated degree-days above 6.5 °C (DD6.5) was determined to be RF/mm = 38,06 + 1.258*DD6.5 for females and RF/mm = 37.65 + 1.765*DD6.5 for males. Ovarian development, measured by follicle length and degree of vitellogenesis, was also related to DD6.5 and pterin concentration. The relationship between y1 = follicle length (mm) and x = DD6.5/200 was y1 = 0.11 + 0.78* [1−exp(− 18.34*x)]**99.86 and between vitellogenic stage (y2) and x was y2 = 0.04 + 3.96*[1−exp(− 11.48*x)]**6.67. Stable flies had a temperature threshold of 8 °C for oviposition.

Production of sex pheromone was induced during the photophase, a time during which pheromone is not normally produced, in females of Heliothis virescens (F.) and H. subflexa (Gn.) by injection of homogenates and partially purified extracts of the brain – subesophageal ganglion complex of conspecific females or H. zea (Boddie) females or synthetic pheromone biosynthesis activating neuropeptide (PBAN). The amount of (Z)-11-hexadecenal, the major component of the pheromone of both species, increased during the first 60 min after injection of PBAN then leveled off and declined in H. virescens. In H. subflexa, the amount of this aldehyde increased during the first 120 min and declined after 240 min. Studies indicated that extracts of the brain – subesophageal ganglion complex that did not contain neurally produced biogenic amines induced production of as much pheromone as did homogenates containing these compounds. Dose-response studies indicated that the optimal dose of synthetic PBAN for induction of pheromone during a 60-min incubation was 5.0 pmol. In vivo maintenance of pheromone production required continuous stimulation of the pheromone gland.

Supercooling point, biochemical metabolites, and water content of the larvae of Choristoneura fumiferana (Clem.) were measured during pre-diapause and diapause development under laboratory conditions. Supercooling point dropped significantly, from a mean value of −22.9 °C to −31.7 °C during the 3-week pre-diapause development. Supercooling point continued to decline down to −34.5 °C after the beginning of diapause. Water content also dropped significantly during pre-diapause development and was maintained at a low level during diapause. Significant amounts of glycerol were detected only when the larvae were 5 weeks into diapause and the glycerol level continued to increase until week 20 when it was almost 10 times its original level. Glycogen was nearly depleted after diapause, but lipid remained at a relatively high level. Little change in glucose and trehalose content was found during diapause in spite of their initial rise before diapause. Larvae could survive low temperatures close to their supercooling point without freezing but none survived freezing, suggesting that this species is freeze-intolerant. First-instar larvae were found to excrete green material out of their body within 5 days after emergence. Removal of this material from the insect body coincided with a significant drop in supercooling point, indicating that a potential nucleating factor might be involved in the green material. The implications of these results for the overwintering strategy of C. fumiferana are discussed.

In southern Alberta, alfalfa seed yields are related to the amount of pollination that occurs before mid-August by the major pollinator, the alfalfa leafcutter bee, Megachile rotundata (F.). Cutting the leaves causes wear to the bee’s mandibular teeth and could reduce the bee’s pollination efficiency and, ultimately, seed production. A method is described for employing digital image analysis to measure mandibular tooth areas for alfalfa leafcutter bees. The method is relatively quick and has high precision and repeatability. This method was used to measure the area of the mandibular teeth for leafcutter bees, before and after foraging in alfalfa seed fields, to evaluate differences in mandibular wear. Analysis of mandibles showed that foraging leafcutter bees collected in late July had significantly smaller tooth areas than pre-foraging bees collected prior to release in June.

Descriptions are given of the fundatrix, alate and apterous viviparous females, ovipara, and the alate male of Sitobion blackmani sp.nov., collected on ocean-spray, Holodiscus discolor (Pursh) Maxim, ssp. discolor.

An aqueous suspension of the nuclear polyhedrosis virus of Lymantria dispar (L.), LdNPV, was fed to third-instar caterpillars of L. dispar and 46 species of nontarget Lepidoptera in four successive. 24- to 48-h doses of 3 × 104 polyhedral inclusion bodies (PIBs) in 2 μL applied to small pellets of artificial diet or isolated surfaces of foliage. Adults of the fly Cyrtophleba coquilletti Aldr., and adult males of the bee Megachile rotundata (Fabr.), were assayed with a single dose of 1.2 × 105 PIBs in 2 μL of 30% sucrose solution. Only those specimens that completely consumed the dose(s) were transferred to appropriate maintenance conditions for 7–10 days whereupon they were frozen. Samples of macerates of experimental specimens were dot-blotted onto nylon membranes on which whole genomic LdNPV DNA-probing and chemiluminescence techniques were used lo show presence of LdNPV DNA. With reference to positive and negative controls, the 48 nontarget species were diagnosed as nonpermissive of LdNPV but the target species was clearly infected. This study demonstrates a high degree of host-specificity of LdNPV.

We present calculations of droplet sizes and product potencies that are theoretically required to deliver a lethal dose of Bacillus thuringiensis in one droplet to larvae of the eastern spruce budworm in aerial spray applications. The calculations are based on estimates of the dose required for 50% and 95% mortality [4.3 and 26.9 International Units (IU), respectively] and of the lowest dose that caused discernable feeding inhibition (0.5 IU) in force-feeding assays with sixth-instar larvae. For products containing 12.7–16.9 billion IU (BIU) per litre, the most widely used potency range, a 150- to 160-μm droplet is needed to deliver an LD95 and an 80- to 90-μm droplet to deliver an LD50, whereas droplets down to 40 μm are expected to cause extensive feeding inhibition. Our calculations suggest that current application prescriptions result in the delivery of a marginally effective dose to the target foliage and that budworm larvae have to ingest multiple droplets to obtain a lethal dose, a process that is thought to contribute to inconsistent spray efficacy. We predict that dose acquisition can be maximized by increasing product potency to 95 BIU/L, which would enable larvae to acquire a lethal dose by ingestion of only one or two droplets in the size range that is most commonly encountered on coniferous foliage (≤ 80 µm) after aerial application.

Increased seed yields often result when alfalfa fields are burned in spring. The main pollinator of seed alfalfa in Alberta is the alfalfa leafcutter bee, Megachile rotundata (F.), that cuts pieces of leaves to build thimble-like cells. One hypothesis for increased seed yield is that alfalfa leaves from burned fields may be easier for the bees to cut. Cutting of leaf pieces causes progressive wear to the mandibles, which could decrease bee efficiency, resulting in reduced pollination and lower seed yields. An image analysis method was used to measure the mandibular wear of leafcutter bees from burned and unburned alfalfa fields. No consistent difference in the amount of wear between bees foraging in burned or unburned fields was found.

The sensory structures of the cephalic segment of first- and third-instar Arachnidomyia aldrichi (Parker) (Diptera: Sarcophagidae) larvae were examined by scanning electron microscopy. Larvae were prepared by methanol freeze substitution, which effectively preserved the structure of these membranous specimens. Sensilla of first and third instars are described and compared with respect to differences in the sensory requirements of these instars. Sensilla numbers and types were similar in both instars, although the sensilla of third instars were larger than those of first instars. None of the external sensory structures was unique to one or the other instar. The cephalic sensory structures of A. aldrichi are also similar in arrangement and structure to those reported for other saprophagous and herbivorous muscomorph dipteran larvae.

Ten European species of Trichogramma were morphometrically analysed by means of 19 male characters. Multivariate analyses permitted the estimation of interspecific divergences. These studies confirmed that the most discriminant characters are borne by antennae and genitalia; they distinguished all the analysed species except T. brassicae Bezdenko and T. voegelei Pintureau. The minutum and pretiosum groups on one hand, and the pintoi and perkinsi groups on the other, are morphologically very close. The dendrolimi group is more distantly related to the minutum and pretiosum groups than to the evanescens group.

Mass storage of honey bee (Apis mellifera L.) queens over the winter was investigated in colony banks, with each queen held in her own cage within a colony. The major treatments included: (I) a single queen wintered in a small nucleus colony (control); and colony banks with 24 or 48 queens, each held individually in (II) screen cages that prevented workers from entering the cage, but allowed access for queen tending, (III) queen-excluder cages (queen-excluder material has openings of about 55 mm that prevent the larger queen but not the smaller workers from passing through the material), or (IV) screen cages until January and subsequent transfer to mini-nuclei until late March. Queens held in excluder cages showed poor survival in all 3 years of testing, and this system was not viable for commercial use; survival for any 1 year, or any excluder treatment, was never greater than 25%. In contrast, a 2-year average of 60% queen survival was found for queens that were stored in individual screened wooden cages within queenless colony banks. We found no differences in survival of banked queens that were moved between colonies monthly and those that remained in the same colony for 6 months. The success of these systems required the (a) preparation of colony banks that contained large numbers of adult workers produced by maintaining colonies with two queens during the previous summer, (b) removal of laying queen(s) during the storage period, (c) feeding of colonies well, and (d) insulation of colonies in groups of four, to preserve heat and reduce worker clustering in the winter. Surviving queens from winter storage systems were virtually identical in quality and colony performance to control queens the subsequent season. The annual profit for a commercial beekeeper who does his/her own labour for storage and hires workers for queen production was calculated as $16,625 when 4800 queens are stored over the winter, and sold for $10 each in the spring. Thus, mass queen storage using our successful systems is both biologically and economically viable.

Two techniques for sexing adults of the white pine weevil Pissodes strobi Peck are described. Both techniques are based on the external anatomy of the terminal segments of the abdomen as viewed with a dissecting microscope.

Adult Calosoma sycophanta L. (Carabidae: Coleoptera) male and female pairs in a laboratory arena were observed for up to 30 days with a video recorder. Beetles were visible (i.e. not hiding) or in soil (i.e. female ovipositing) especially during night hours. Feeding on gypsy moth larvae occurred any time of the day or night. Male and female beetles were most active during the time when female beetles were ovipositing. Females spent more time eating and staying in soil than did males, but males tended to move around the arena more than did females. Based on results from this study, it is expected that, in the forest, C. sycophanta females will spend most of their time hidden in leaf litter or ovipositing. Males are more likely to be seen because they spend more time moving about, probably seeking mates.

The insecticide Foray 48B (Bacillus thuringiensis var. kurstaki Berliner) was applied undiluted at 30 BIU per ha to control spruce budworm, Choristoneura fumiferana (Clem.), in a mixed boreal forest stand of balsam fir, Abies balsamea (L.) Mill., and black spruce, Picea mariana (Mill.) B.S.P. When the treatment was timed to coincide with the early flushing of balsam fir shoots, the corrected budworm population reductions were 74 and 52% on balsam fir and black spruce, respectively. This treatment resulted in 19 and 8% defoliation on the two respective species. When the insecticide application was timed later to coincide with the late flushing of black spruce shoots the corrected population reductions were 93% on balsam fir and 72% on black spruce. Defoliation of the two species was 29 and 10% respectively, following this treatment. Larval survival on both species after the spray timed for black spruce (0.8 and 2.2 larvae per 45-cm branch on balsam fir and black spruce, respectively) was significantly less (P = 0.05) than that observed after the spray timed for balsam fir (4.6 and 4.2 larvae per 45-cm branch on the respective host species).The data indicate that the spray timed to correspond with the flushing of black spruce was generally more efficacious than the spray timed to impact on newly flushed balsam fir; nevertheless, the results raise the question as to how B. thuringiensis insecticides impact on early-instar budworm larvae when there is no preferred current year foliage on which the insects can feed.

Traps baited with a 95:5 blend of E:Z-11-tetradecenal, the sex pheromone of the spruce budworm, Choristoneura fumiferana (Clem.), were deployed throughout several summers in Ontario to determine what other Lepidoptera were captured that might be confused with the male C. fumiferana. Eight other species of Tortricidae were captured with sufficient frequency to suggest that they were attracted to the traps: Choristoneura conflictana Wlk. (the large aspen tortrix), six species of Acleris, and one Gretchena species. Of these, C. conflictana can easily be confused with C. fumiferana. The evidence suggests that male C. conflictana were not attracted by the pheromone, but blundered into the traps. They are very similar morphologically to male C. fumiferana, but can be differentiated with care.

The North American members of the genus Operophtera Hübner (Lepidoptera: Geometridae) are revised to include three species: O. brumata (L.), O. bruceata (Hulst), and O. danbyi (Hulst). Operophtera occidentalis (Hulst) is now treated as a subspecies of O. bruceata. All species are illustrated and characters to distinguish the species are given. The most useful characters for separating O. brumata from O. bruceata include the following: (1) hindwing dorsal surface with discal dot, which is almost always visible on O. bruceata but absent from O. brumata; (2) forewing colour, which is grey-brown or light brown in O. bruceata but reddish-brown in O. brumata; (3) abdomen colour, which is golden-brown to brown in western O. bruceata but brown in O. brumata; and (4) the costa of the forewing ventral surface, which is usually golden-brown in O. bruceata but brown in O. brumata. The structure of the genitalia of these two species allows hybridization between O. bruceata males and O. brumata females, but not vice versa.Hypothesized species interrelationships between palaearctic and nearctic Operophtera are illustrated in a cladogram. Maps for the distribution of each species are also included.