Records of bumble bees from four collecting trips (1977, 1978, 1988, and 1994) in northern Britain show apparent changes in the incidences of two species. Until 1988, Bombus muscorum (Linnaeus) and Bombus pascuorum (Scopoli) were found in the counties of Cumbria, Durham, and North Yorkshire. Only B. muscorum was found in the Orkney Islands in 1978. In 1994, however, B. pascuorum was found abundantly in all of these areas, and in the Orkney Islands we could find only a single B. muscorum. From these data, B. pascuorum appears to have been replacing B. muscorum in some parts of northern Britain.

Larval growth and pupal parameters of the forest tent caterpillar (Malacosoma disstria Hübner) reared on the foliage of two host trees (Populus tremuloides Michx. and Acer saccharum Marsh.) and one nonhost tree (Acer rubrum L.) were quantified. This was achieved by undertaking a larval development bioassay under controlled laboratory conditions, but using fresh leaves collected in two field seasons. Larvae fed foliage of P. tremuloides grew exponentially and began to pupate after 3 weeks. Larvae fed with A. saccharum gained significantly less weight and had a reduced number of larvae pupate, and the pupae weighed significantly less than their counterparts fed on P. tremuloides. All larvae that were fed the foliage of A. rubrum died within 2 weeks. A nutritional utilization bioassay with fourth-instar larvae revealed that the foliage of A. saccharum has a growth-inhibitory component, whereas that of A. rubrum is antifeedant. Reasons are discussed for the discrepancy between the many reports of A. saccharum being a food host for M. disstria in the field and the laboratory results.

Using gas chromatography and gas chromatography – mass spectrometry analyses of sex pheromone gland volatiles, we identified E- and Z-11-tetradecenals (E:Z-11-14:Aid) in an 85:15 blend of E:Z as the primary sex pheromone components of Croesia semipurpurana (Kearfott). Similar chemical analyses of sex pheromone gland extracts indicated the presence of the congeneric acetates (85:15 E:Z-11-14:Ac) and their saturated analogue (14:Ac); in addition, 85:15 E:Z-11-14:Alds were present at 5% of the acetates. The E:Z-11-14:Alds alone elicited trap capture; admixtures of saturated and unsaturated acetate analogues exhibited no significant synergistic or inhibitory effects. PVC rods with an 85:15 E:Z-11-14:Ald blend is recommended as a trap bait for monitoring population trends. It is unknown whether or not the components identified here represent the complete pheromone blend of this species; data from traps suspended 1.5 m above the ground versus those suspended 10 m above the ground suggest that future field studies may need to be conducted with traps positioned in the tree canopy.

Arthropods associated with Populus coarse woody material (CWM) were sampled from aspen-mixedwood stands in north-central Alberta using rearings from wood bolts and flight-intercept traps attached to snags. More than 39 000 arthropod specimens were collected over 3 years, comprised mainly of Coleoptera, Diptera, Hymenoptera, and Acari. Detailed analyses are provided to compare the number of species, standardized abundance, and trophic structure between collecting methods for 257 saproxylic species of Coleoptera. Abundance of beetle species, from both rearings and window traps, and rarefaction estimates of species richness indicate little difference between methods with respect to expected number of species. However the abundance of particular beetle families differed significantly between methods, with the Aderidae, Anthicidae, and Scaphidiidae collected mainly in rearings and the Micropeplidae, Bostrichidae, Cephaloidae, Clambidae, Salpingidae, and Tenebrionidae more commonly collected with window traps. Fungivorous and predatory beetles were more abundant in CWM than wood borers, scavengers, or taxa with undetermined feeding habits, but the two methods revealed similar overall trophic structure. To census the variability in saproxylic arthropod faunas from CWM, a combination of collecting methods is recommended.

Photoperiodic responses are described for five clones of the potato aphid, Macrosiphum euphorbiae (Thomas) (Homoptera: Aphididae), from Manitoba, Canada, a region with a strongly seasonal, continental climate. When exposed to long nights, parthenogenetic wingless females produce winged males and parthenogenetic winged females that subsequently produce mating females. The young adult males and winged females are restless and take flight readily, which is typical of a post-teneral migratory phase that could carry them to a winter host. These traits are characteristic of host-alternating species. However, wingless females also produce mating females, and winged females also produce parthenogenetic wingless females, traits which are characteristic of nonhost-alternating species. Clones differ in the frequencies of phenotypes they produce, some being more host-alternating than others. Critical night lengths are shortest and frequencies of males highest for clones that are closest to the host-alternating type of life cycle. The importance of phenotypic and genotypic plasticity in the life cycle is discussed.

The potato aphid, Macrosiphum euphorbiae (Thomas) (Homoptera: Aphididae), is a host-alternating species and an important pest of Canadian flax. Populations of this aphid are highest in flax when the weather is warm and dry in July. Field-plot studies show that populations of the potato aphid increase rapidly in late July and early August and decline rapidly in mid-August. In some years potato aphids die because of a fungal epizootic or drought-induced senescence of the crop, but usually these factors do not account for the population decline. Field cage studies show that the potato aphid emigrates from the crop in mid-August. The photoperiodic response of the potato aphid and resulting emigration explain the population decline in flax, which occurs in mid-August each year regardless of the growth stage of the crop, population density, or average temperature at the time of the photoperiodic cue. Male and mating female potato aphids, born at the end of August, have time to develop, mate, and lay eggs before temperatures drop below the developmental threshold. The population decline assures that farmers need not sample or control the potato aphid in flax after mid-August.

Laboratory assays and field surveys showed that Ascosphaera larvis (Bissett) is a pathogen of alfalfa leafcutting bee larvae, capable of causing high mortality in commercial populations. In one population, over 21% of bees were found to be infected by A. larvis. However, overall levels of the disease are low and it is unlikely that this pathogen poses an immediate threat to commercial leafcutting bee populations in Canada. The LD50 was determined to be 1.9 × 105 spores/bee. Elevated levels of CO2 are required for in vitro spore germination. The disease can easily be diagnosed within bee cells by X-ray radiography, thereby enabling disease levels to be monitored using conventional methods utilized by the industry to monitor leafcutting bee quality.

The mature larvae of three species of Hoplitis, namely Hoplitis anceyi (Pérez), Hoplitis anthodemnion Michener, and Hoplitis nitidula (Morawitz), are described and compared with the other known larvae in the genus. The morphology of the spiracles, antennal discs, and antennal papillae, the absence of a seta on the mandibular basis, and the shape of the vertex permit the characterization of each species. Furthermore, H. anthodemnion has the integument covered by setiform spicules. Nevertheless, there is no clear separation between the three species studied and those previously known, and larval morphology does not support the consideration of Anthocopa and Hoplitis as separate genera.

Seasonal abundance of Sitobion avenae (F.) and Rhopalosiphum padi (L.) was monitored in Nova Scotia winter wheat plots. Rhopalosiphum padi was the more common aphid species during "heading out." Winter wheat cultivars differed in their resistance to R. padi development; the highest reproductive rate was on ’Absolvent.’ The effect of chemicals used in intensive cereal management on R. padi and Coccinella septempunctata (L.) was assessed. Dimethoate and carbaryl caused similar high mortality to both insects, but pirimicarb was more toxic to the aphid than to its predator. Over a 2-year period, field plots that received regular pirimicarb treatments for selective aphid control early in the growing season showed a 9% increase in wheat yield, compared with the checks and plots that received carbaryl. Wheat yield increased 18% when pirimicarb was used later in the season; when applied in both periods, pirimicarb gave a total yield increase of nearly 30%. Late applications of carbaryl alone, or in combination with pirimicarb, increased yields by only 9% over the controls. Half of the yield increase (18% vs. 9%) with late season control by pirimicarb was lost with the addition of carbaryl, which minimized the C. septempunctata population for nonselective insect control. Rhopalosiphum padi numbers from June 20 to July 15 had the greatest impact on yield in these plots, and natural control agents including C. septempunctata accounted for a 9% increase in yield.

Blanchardia gen.nov. and its type species Blanchardia poikila sp.nov. are described and the new combination Blanchardia capitophoroides is established for Macrosiphum capitophoroides Blanchard, 1944. The new genus forms part of the Macrosiphum group and it is characterized by the presence of one to three poorly defined rows of cells on the apex of siphunculus. Both species live on Senecio in Patagonia, Mendoza Province, Argentina.

An evolutionary model was constructed for the white pine weevil (Pissodes strobi Peck). This weevil attacks Sitka spruce [Picea sitchensis (Bongard) Carriere], and Sitka spruce trees have two forms, one being susceptible to the insect attacks and the other being resistant to attack. There is a fear that insects may develop tolerance to the resistant trees. The strategy of interplanting susceptible and resistant trees to minimize the likelihood of the insects developing tolerance mechanisms to circumvent the resistance is examined. It is found that if only one gene locus is involved, the development of tolerance occurs more quickly than if resistance is governed by two independent loci. The rate of evolution of tolerance to tree resistance is retarded by increased adult survivorship, the degree of recessiveness of the gene, preferential attack of susceptible trees, redistribution of intolerant insects from resistant to susceptible trees, and the immigration of wild-type insects.

Diplolepis nodulosa (Beutenmüller) induces small, monothalamous, prosoplasmic galls in stem tissues of Rosa blanda Aiton. Adults and galls are redescribed and notes on distribution, host records, morphological variation, and a comparison with related species are presented. Galls are commonly attacked by the inquiline Periclistus pirata (Osten Sacken). Data on life history and mortality of inducers and inquilines, along with seasonal variation in gall density, were obtained from a study site near Sudbury. Ontario, in 1993 and 1994. Inquilines killed 55% of the inducer population in 1993 and 65% in 1994. The abundance and density of galls fluctuated over the 2 years; however, the proportion of galls modified by inquilines remained constant. Six species of parasitoids caused an additional 17% inducer mortality. Aprostocetus sp. was the dominant parasitoid of D. nodulosa, whereas the other five species were incidental. The assemblage of parasitoids associated with galls modified by P. pirata caused 13% inquiline mortality and include seven species, of which Eurytoma spp. and Caenacis sp. were dominant. The unique aspects of the D. nodulosa gall system are discussed.

Two new species of Diapheromera, D. kevani and D. petita, are described from Mexico, the first record of these species and of the genus from Baja California. They were found while studying the stick insects (Phasmatoptera) of the Baja California Peninsula.

In two-choice laboratory feeding trials in Petri dishes, adult carabid beetles, Pterostichus corvus (Leconte) and Pterostichus femoralis (Kirby), ate a higher percentage of grasshopper eggs, Melanoplus bivittatus (Say), than of cat food. Pterostichus corvus ate more eggs than did P. femoralis. Grasshopper eggs buried in soil in terraria were eaten by P. corvus adults at more than twice the rate of eggs exposed on the soil surface; predation rates at depths of 2.5 and 5 cm were the same. In plant-propagation trays, predation by P. corvus of buried grasshopper eggs was studied under three types of ground cover: Nicotiana seedlings, with rosette-form growth habit; barley seedlings, which exhibited upright growth; and bare ground. A significantly higher percentage of eggs was eaten under the Nicotiana than beneath the other types of ground cover, and predation rates did not differ between the barley and bare-ground treatments. Pterostichus corvus appears to be a suitable candidate for enhancement of natural biological control of grasshopper eggs, and manipulation of vegetation cover in grasshopper egg beds may be an effective technique for enhancing predation rates.

A redescription of Myzocallis (Lineomyzocallis) melanocera Boudreaux & Tissot is given, and Myzocallis (Lineomyzocallis) neoborealis sp.nov. and Myzocallis (Lineomyzocallis) atropunctatus sp.nov. are described. Lectotypes for M. (L.) melanocera and Myzocallis (Lineomyzocallis) walshii (Monell) were designated. Myzocallis (Lineomyzocallis) occultas Richards is declared a new synonym of M. (L.) walshii. The taxonomic affinities of these aphids are discussed.

Two opposing hypotheses are tested regarding the choice of oviposition sites by female Aedes togoi (Theobold) mosquitoes: (i) conspecific avoidance—females discriminate against sites harboring conspecifics to reduce intraspecific competition for their offspring and (ii) conspecific attraction—females prefer sites with conspecifics because their presence indicates suitable conditions for larvae. Under laboratory conditions, A. togoi females laid many more eggs on rearing water (LRW) containing conspecific larvae, their waste, bacteria, and food supplements than on rearing water alone (RM). In another experiment, females showed an oviposition preference for LRW sites that were devoid of A. togoi eggs compared with those harboring 50 (0.3 eggs/mL) conspecific eggs. Further, it was discovered that females laid their eggs at several sites rather than at a single suitable site. Possible reasons for such choices are discussed.

The nun moth (NM), Lymantria monacha (L.), is one of the most important defoliators of coniferous forests in Eurasia (Bejer 1988). It was reportedly established near Brooklyn, New York (Holland 1941), but according to Ferguson (1978) “either the report was wrong or monacha did not persist, as there is no evidence of its presence now.” The potential entry of NM to North America poses a severe threat to the vitality, biodiversity, and stability of coniferous forests. The economic and environmental costs of existing exotics and the potential entry of new ones, such as NM, justify proactive management and heightened international quarantine efforts.

Recent identification of an attractive and species-specific pheromone blend in NM from the Czech Republic (Grant et al. 1996; Gries et al. 1996) provides the opportunity to develop pheromone-based NM detection surveys in North America. However, as has been demonstrated for other moth species (Klun et al. 1975; Thompson et al. 1991; Tóth et al. 1992), pheromone blends of geographically wide ranging species, such as NM, may be regionally specific. Therefore, attraction of Asian NM males to the European NM pheromone blend needed to be tested.

The lengths of the scale bars were left off three of the figures. On page 727 for Figs. 18–21 the caption should read: Scale bar = 0.5 mm; on page 728 for 13gs. 22–25 the caption should read: Scale bar = 0.2 mm; and on page 730 for Figs.31–35 the caption should read: Scale bar = 0.5 mm.