Bathyplectes anurus (Thoms.) has displaced B. curculionis (Thorns.) as the main larval parasitoid in populations of the alfalfa weevil, Hypera postica (Gyll.), in eastern Ontario. Following its belated spread to the Bay of Quinte dairy belt, it used a combination of r and K strategies to assert its superiority: a greater reproductive capacity, more rapid search and handling, and more aggressive behaviour. Also, it is not subject to encapsulation by the host and reduces direct competition with the entomopafhogenic fungus Zoophthora phytonomi (Arthur) by laying its eggs in older hosts that have a greater probability of escaping death from disease. Taken together, these factors have enabled it to perform better than B. curculionis and to displace it in the host–parasitoid community. Moreover, it may have the potential to stabilize weevil populations during years when the fungus is enzootic.

Leafy spurge (Euphorbia × pseudovirgata [Schur]) is an herbaceous perennial and serious weed of European origin that has been accidently introduced into North America. The European anthomyiid flies Pegomya curticornis (Stein) and Pegomya euphorbiae (Kieffer) are found on several spurge species in Europe and also attack leafy spurge. The two flies induce identical galls on the subterranean stems of their host plants, and the shoots wilt and die. Eggs are laid on the shoot tip, and the larvae bore into the stem by eating pith which is later replaced by callus. This is a rare example of an insect with both boring and gall-inducing feeding strategies. Galls are induced when larvae feed on the ring of vascular tissue. There is no proliferation of nutritive cells but instead thick layers of gall parenchyma are produced. The vascular connections are broken at the gall level and concentric vascular bundles appear in the cortical and gall parenchyma. After pupation an inner periderm differentiates around the chamber surface.

Body weights were measured for Podisus maculiventris (Say) (Heteroptera: Pentatomidae) given low prey inputs. Predators were fed green bean slices ad lib and a single mealworm larva (Tenebrio molitor L.) of one of two size classes, for a 24-h period every 1, 2, 4, 8, or 16 days. Other treatments included predators fed to excess of daily attacks, predators given only green bean slices, and predators given no food. Results showed that predators fed bean slices maintained body weight after an initial decline, whereas predators given no food lost weight continually until death. Predators maintained weight when fed prey ad lib, and when fed prey of either size daily. Those fed at longer intervals lost weight between feedings, and weight fluctuations increased as the interfeeding interval increased. Slopes of weight change between feedings did not differ significantly for predators fed at 2- through 16-day intervals. During oviposition, predators lost about 15 mg of body weight. Egg clutches comprised about 60% of the weight lost. Egg weights did not differ among treatments. The results suggest that P. maculiventris can survive long periods without prey, and adjusts its weight loss by reducing reproductive effort when prey become scarce. The importance of these adaptations for P. maculiventris to sustain populations in agricultural systems is discussed.

Neosensoriaphis gen.nov., type-species N. parva sp.nov., Subiziphya gen.nov., type-species S. clauseni sp.nov., and Thripsaphis unciniae sp.nov. are described. The taxonomic position of these aphids is discussed.

Chaetocnema concinna (Marsham, 1802), a European flea beetle, is reported for the first time from Canada. Preliminary collection data indicate that it may feed on the same host plants as in Europe. It has been collected to date in Prince Edward Island, Nova Scotia, and Maine.

The development of spruce cone axis midge, Dasineura rachiphaga Tripp, and its parasitoids, Platygaster lucida Fouts and Torymus sp., was studied in relation to the availability and development stage of black spruce, Picea mariana (Mill.) B.S.P., cones.

Spruce cone axis midge inhabiting black spruce cones appeared to undergo an extended diapause. This phenomenon probably was related to the production of cones. Platygaster lucida also appeared to undergo extended diapause and the proportion of P. lucida extending their diapause paralleled that of spruce cone axis midge which suggested a close dependance to their host.

Spruce cone axis midge, P. lucida, and Torymus sp. emerged from mature cones about the same time and were closely synchronized with the availability of black spruce flowers.

External morphological characters of the spruce cone axis midge that separate the two sexes in the pupal stage were described.

The effects of trap design, lure concentration, lure age, and trap maintenance on the catch of western spruce budworm moths, Choristoneura occidentalis Freeman, in pheromone traps were tested in light to moderate infestations near Ashcroft, B.C. High cumulative moth catches reduced the trapping efficiency of both the sticky traps and the non-sticky Uni-traps relative to traps from which the moths were removed every 2 days. Correlations between the total season’s catch and larval density per plot in the same and following generations were not significant (P>0.05) for any of the eight combinations of trap design, lure concentration, and maintenance regimen tested. However, by dividing the mean moth catch in Uni-traps by either the basal area or foliage biomass per hectare in each plot, correlations with the following year’s larval density were significant (r 2 = 0.77–0.98; P<0.05; n=5).

Experiments were conducted using balsam fir twigs treated with Bacillus thuringiensis Berliner to examine the influence of temperature and exposure time on mortality of spruce budworm, Choristoneura fumiferana Clemens. Twigs were sprayed with a commercial formulation (8.4 BIU/L) using droplets of 40–70 μm diameter at densities, ranging from 0.5 to 5.5 droplets per needle. Temperature affected progression but not the level of cumulative mortality during 14 days of feeding on sprayed foliage. The LT50 decreased from 12–17 days at 13°C to 2–4 days at 25°C, depending on droplet density. Temperature between 13 and 25°C had a limited effect on dose acquisition because 40–60% of the larvae were able to acquire a lethal dose within 1 day of feeding on foliage with 0.5–1.5 droplets per needle, regardless of temperature. Under these conditions dose acquisition was not limited by temperature-dependent consumption of foliage, but rather by feeding inhibition associated with the dose initially ingested. This also limited the influence of exposure time; a 7- or 14-fold increase in exposure time increased larval mortality at most by 25%. Implications of these findings for improving efficacy of B. thuringiensis in forestry applications are discussed.

Larvae of Arrenurus bartonensis Cook, Arrenurus birgei Marshall, Arrenurus neobirgei Cook, and Arrenurus rotundus Marshall are described for the first time. Larvae of A. rotundus can be distinguished reliably from the other three by differences in morphology. Larvae of A. bartonensis, A. birgei, and A. neobirgei are very similar, but can be separated by comparing shape and size of the excretory pore plate, and by measurements of the dorsal plate and the tarsus of the third leg.

Twenty-one species of fleas, seven of which are considered true ground squirrel fleas, were collected by various means from Spermophilus richardsonii (Sabine), S. tridecemlineatus (Mitchell), and S. franklinii (Sabine) in Manitoba. Opisocrostis tuberculatus tuberculatus (Baker), O. labis (Jordan and Rothschild), Neopsylla inopina Rothschild, and Rhadinopsylla fraterna (Baker) are ground squirrel fleas reported from Manitoba for the first time. These, in addition to Oropsylla rupestris (Jordan) and Thrassis bacchi bacchi (Rothschild), were restricted to the southwestern region of the province, but Opisocrostis bruneri (Baker) was collected throughout the range of the ground squirrels, irrespective of location. Fourteen species collected were considered accidental on ground squirrels, one of which, Tamiophila grandis (Rothschild) (an eastern chipmunk parasite), was recorded for the first time in the province.

The male meiotic karyotypic formula of Conophthorus coniperda (Schwarz) (Coleoptera: Scolytidae) is 9AA + XY. This karyotype differs from C. resinosae Hopkins and C. banksianae McPherson, both of which have the karyotypic formula of 8AA + XY. Supernumerary chromosomes were found in different populations of C. resinosae and C. banksianae but were absent in C. coniperda. No geographic variation in the karyotypes of the three species was observed. The karyotypic formulae confirm the designations of C. coniperda and C. resinosae by morphological characters, but do not support the designation of C. banksianae as a distinct species.

The structure, distribution, and type of sensory hairs on the palptarsus of female Varroa jacobsoni Oudemans were examined by scanning electron and phase contrast microscopy. The two large, peg-like setae with apical pores are chemoreceptor sensilla chaetica. The seven slender, round tipped setae, stained with crystal violet at the hair cuticle, are considered to be the chemoreceptor sensilla trichodea. A number of long hairs that did not stain with crystal violet are trichoid tactile setae. The possible functions of these sensilla were discussed.

Gyrinus cavatus sp.nov. (type locality: Floral, Saskatchewan, Canada), from across Canada, is compared with G. minutus Fabricius. The two species are broadly sympatric in the northern boreal and transition forests, but G. cavatus is more abundant southward into the northern United States. Therefore, the subgenus Gyrinulus Zaitsev is not monobasic, but has three species in North America, including G. rockinghamensis LeConte.

From 1976 to 1978, 1300 mated females of Olesicampe geniculatae Quednau and Lim were released near Quebec City during a severe infestation of the mountain ash sawfly, Pristiphora geniculata (Hartig). Both cage and open releases were made. The interactions among the mountain ash sawfly, the imported primary parasite O. geniculatae, and the indigenous hyperparasite Mesochorus globulator (Thunb.), and the effect of O. geniculatae on the host population during and after the establishment phase, are reported. In 1984, O. geniculatae was recovered from all over southern Quebec. Parasitism ranged from 6 to 94%. Concurrently, infestation levels by the mountain ash sawfly declined significantly, and since 1985, the insect has almost disappeared in Quebec. With an annual spread of about 50 km per year after successful establishment, O. geniculatae now covers an area 1000 km in diameter. No major infestation by the mountain ash sawfly has been recorded in Quebec during the past 7 years. The introduction of O. geniculatae is rated as a complete success in classical biological control.

The 70 species of Platycheirus (including Carposcalis, Pyrophaena, and much of Melanostoma of North American authors) occurring in the Nearctic Region north of Mexico are revised. Twenty-three species are described as new and new names are proposed for two species. Eighteen new synonyms and 14 new combinations are proposed; one variety name is given specific status. Six palaearctic species are recorded from North America for the first time, and one nearctic species from Europe, for a total of 23 holarctic species.

Laboratory bioassays and field tests demonstrated that the (+) enantiomer of endo-brevicomin is an antiaggregation pheromone for the western balsam bark beetle, Dryocoetes confusus Swaine. (+)-endo-Brevicomin significantly reduced the response of beetles of both sexes to the aggregation pheromone exo-brevicomin in laboratory bioassays and in field experiments using multiple-funnel traps. It also prevented attack on subalpine fir, Abies lasiocarpa (Hook) Nutt., trees baited with exo-brevicomin. The (−) enantiomer of endo-brevicomin was inactive. These results suggest that (+) or (±)-endo-brevicomin has potential for protecting selected trees from attack, or suppressing western balsam bark beetle activity in high hazard or infested stands.

The responses of Ips latidens (LeConte) to multiple-funnel traps baited with various monoterpenes were determined in stands of lodgepole pine in British Columbia. β-Phellandrene was attractive to I. latidens in the absence of the pheromone ipsenol. β-Phellandrene increased the attraction of I. latidens to ipsenol-baited traps while α-pinene, 3-carene, terpinolene, and myrcene reduced trap catches. Differential responses by males and females to sources of ipsenol with or without β-phellandrene suggest that the information conveyed to males differs from that conveyed to females. Species-specific responses to monoterpenes by I. latidens and three sympatric species of scolytids suggest that unique combinations of kairomones could be important in facilitating matings with conspecifics. Pheromones need not be the sole constituent of species-specific chemical messages.

Data from larval head capsule measurements are used to determine allometry of size for final-instar siblings Simulium truncatum (Lundström) (= EFG/C) and S. rostratum (Lundström) (= ACD) of the S. venustum/verecundum complex (Diptera: Simuliidae). Measurements were evaluated using principal axis and major reduced axis regression. Isometry of size was accepted for only some ratios and it is argued that a character’s “environmental stability” should be assessed before it is considered as a taxonomic character.

Two exotic species of Xyleborus (Coleoptera: Scolytidae) of Asian origin have recently been detected in the United States. Xyleborus pelliculosus Eichhoff has been collected in Pennsylvania and Maryland, and X. atratus Eichhoff from Tennessee, Georgia, Maryland, Virginia, and West Virginia. Descriptions of both species and a revised, illustrated key to members of the genus Xyleborus in eastern North America are presented. An explanation is proposed for the large numbers of recent introductions of exotic ambrosia beetles from eastern Asia into eastern North America.

The performance of unbaited emergence traps and attractant-baited pitfall and flight traps was compared on the basis of suitability to produce population indices for two beetles, Steremnius carinatus (Boheman) and Hylastes nigrinus (Mannerheim), colonizing roots of Douglas fir in northern California. These beetles transmit Ceratocystis wageneri Goheen and Cobb, the fungus causing black stain root disease in Douglas fir. Trap sites were near stumps along transect lines through recently logged areas. Pitfall traps were judged the most promising for both species based on their relatively high catches and low expense. Although catch by emergence traps was low for both species, they appeared to catch the majority of S. carinatus. For both species, pitfall trap catches varied with date, study area, trapping line within study area, and stump within line. A number of variables, such as diameter of stump or type of ground cover, were significantly correlated with trap catch, and made significant contributions to linear models with catch as the dependent variable. Differences between study areas in the effect of variables on catch, and the possibility that pitfall trapping is subject to artifacts, suggested that the results of pitfall trapping need to be carefully scrutinized if they are to be used as a population index.