Developmental rates, lower developmental threshold, host selection among three species of aphid, and head capsule width were determined for the parasitoid Aphelinus sp. nr. varipes (Foerster) (Hymenoptera: Aphelinidae). Aphid species used were Russian wheat aphid, Diuraphis noxia (Mordvilko), western wheat aphid, Diuraphis tritici (Gillette), and corn leaf aphid, Rhopalosiphum maidis Fitch. Developmental rate was determined at five constant temperatures, 11.3, 14.7, 19.0, 25.7, and 30.3°C. Developmental times of the wasp were similar in Russian and western wheal aphids, ranging from 88.7 days al 11,3°C to 11.3 days at 30.3°C. Lower developmental threshold was similar in both species, 9.7°C in Russian wheat aphid and 9.4°C in western wheat aphid. Because of the low number of corn leaf aphid s parasitized, it was not possible to compute a parasitoid development threshold in that host. In the host selection test, there were no significant differences in numbers of Russian and western wheat aphids attacked; corn leaf aphid was seldom attacked. The western wheat aphid is a native species that also causes leaf-rolling; we believe it was the primary host of the parasitoid before the arrival of the Russian wheat aphid. Wasps emerging from Russian wheat aphid were consistently larger than those emerging from western wheat aphid. Mean head capsule width for 30 female wasps from Russian wheat aphid was 0.33 mm; from 30 female wasps from western wheat aphid mean head capsule width was 0.20 mm.

Acephate implanted in trunks of black spruce, Picea mariana (Mill.) B.S.P., trees in the fall, 3 weeks before female bud flush, and at female bud flush reduced insect damage to cones and increased seed yields for 1 year. Second-year effects of the implants reduced insect damage to cones, but without increased seed yields. In the 2nd year, cones from trees treated at bud flush had the least insect damage and the highest residues of acephate and its toxic metabolite, methamidophos. Damage to treated cones by the spruce cone maggot, Strobilomyia neanthracina Michelson, the dominant insect in untreated cones, was insignificant in the 1st year and was reduced in the 2nd year.

This review article starts with the discovery of Bacillus thuringiensis Berliner in Japan at the turn of the century and notes that the observations of the early Japanese workers clearly show that they were aware of the toxin-mediated nature of the activity of B. thuringiensis toward insect larvae. The early work in Europe with B. thuringiensis against Ostrinia nubilalis (Hubner) showed that the bacterium had promise as a microbial control agent. The commercial development of B. thuringiensis in France in the late 1930s, and in Eastern Europe and the United States in the 1950s, is traced.

High volume sprays of azinphosmethyl, chlorpyrifos, fenvalerate, permethrin, and phosmet in various concentrations and formulations were simulated on loblolly pine (Pinus taeda L.) foliage in a pine seed orchard in northern Georgia. Persistence of these insecticides under field conditions was determined by weekly bioassays with adult leaffooted pine seed bugs [Leptoglossus corculus (Say)] and gas–liquid chromatography. Fenvalerate was the most persistent insecticide tested. In the first experiment, 0.2% AI fenvalerate caused virtually 100% seed bug mortality in bioassays through the 4th week after treatment, whereas mortality from azinphosmethyl dropped to ca. 14%. By the 6th week, mortality in the fenvalerate treatment was still 91%, even after 10.5 cm of rain. The permethrin treatments persisted for 2 weeks, then mortality declined below 40% at 3 weeks. In the second experiment, fenvalerate at 0.15% AI and 0.075% AI caused 95 and 90% mortality, respectively, after 3 weeks and 16 cm of rain, and the toxicity of the 0.038% and the 0.019% AI fenvalerate treatments lasted only 2 weeks with 12 cm rain. Permethrin in Ambush® EC at 0.2% AI had initial residues of about 150 ppm and caused ca. 84% mortality for 2 weeks with 12 cm rain. Azinphosmethyl WP at 0.2% AI had initial residues of ca. 104 ppm and persisted for 1 week. Seed bug mortality from phosmet at 0.4% AI diminished quickly after 1 week in the field.

Impact of the flower- and shoot-tip-feeding beetle, Brachypterolus pulicarius (L.), on growth, flowering, and seed production of common toadflax, Linaria vulgaris (L.) Mill., was investigated using potted plants. Brachypterolus pulicarius had no effect on root or shoot biomass of attacked plants. Adult feeding by B. pulicarius delayed onset of flowering by 27 days relative to controls. Flowering of attacked plants was suppressed from mid-June until mid-July, but by mid-August flowering was similar to that of control plants. Total seed weight, individual seed weight, and percentage germination were all reduced significantly on attacked plants, resulting in a 74% reduction in number of viable seeds produced. Brachypterolus pulicarius is univoltine in Alberta, overwintering mainly as pupae.

Morphological and distributional data are presented for North American species of the family Chappuisididae, including members of the genera Chappuisides Szalay (subfamily Chappuisidinae), Uchidastygacarus Imamura (subfamily Uchidastygacarinae), and Morimotacarus Imamura and Yachatsia Cook (subfamily Morimotacarinae). The phylogenetic relationships of mites in these subfamilies with other Arrenuroidea are discussed, leading to the conclusion that mites previously placed in the families Chappuisididae and Uchidastygacaridae Imamura probably represent a single, holophyletic group. As a result, the family Chappuisididae is redefined, and four subfamilies are recognized, namely Chappuisidinae, Uchidastygacarinae Imamura, Tsushimacarinae Cook, and Morimotacarinae Imamura. The name Uchidastygacaridae is placed in synonymy with Chappuisididae. New diagnoses are proposed for the family and subfamilies.

Adults of Chappuisides eremitus Cook are redescribed, and adults of seven new species, namely C. anomalus sp.nov., C. neomexicanus sp.nov., C. acadianus sp.nov., C. cooki sp.nov., C. occidentalis sp.nov., C. californicus sp.nov., and C. oregonensis sp. nov., are described for the first time. Deutonymphs of C. acadianus, C. cooki, and C. occidentalis are also described. A new diagnosis is proposed for the genus Chappuisides and subgeneric concepts are reviewed critically.

Adults of Uchidastygacarus (Imamurastygacarus) ovalis Cook, U. (s.s.) imamurai Cook, and U. (s.s.) acadiensis Smith are redescribed, largely on the basis of recently collected specimens including the first known adult males of U. (I.) ovalis. Adult males of U. (s.s.) magnificus sp.nov., adult females of U. virginiensis sp.nov., and deutonymphs and adults of both sexes of U. appalachianus sp.nov. are described for the first time. New diagnoses are proposed for the genus Uchidastygacarus and its subgenera.

Adults of Morimotacarus nearcticus sp.nov., the first known nearctic species of the genus, are described and adults of Yachatsia mideopsoides Cook are redescribed. Deutonymphs of both of these species are described for the first time. The name Yachatsia euforma Habeeb is placed in synonymy with Y. mideopsoides based on study of type specimens and assessment of variability within populations. New diagnoses are proposed for the genera of Morimotacarinae.

A phylogenetic framework for Chappuisididae is outlined and discussed. New distributional data are presented for North American species, permitting the first comprehensive attempt to assess the zoogeography of the family. The family probably differentiated from early derivative mideopsiform arrenuroid stock similar to Nudomideopsidae in Laurasia during the late Cretaceous or early Tertiary. Extant subfamilies apparently originated early in Tertiary times, and the clades that include modern genera dispersed throughout western North America and eastern Asia, and in some cases more extensively on both continents, between the early Tertiary and the Pleistocene. Climatic cooling in late Tertiary times, culminating in glacial episodes during the Pleistocene, resulted in displacement of chappuisidid taxa to various refugial areas south of continental ice sheets. Modern species are in the process of invading recently deglaciated areas in both eastern and western North America, but at differing rates that reflect their vagility, cold-tolerance, and ability to colonize newly established interstitial habitats. Chappuisididae have considerable potential value as indicators of the impact of environmental changes on interstitial freshwater ecosystems.

The Eurasian nabid Himacerus apterus (Fabricius) is reported for the first time for North America. Several individuals have been collected between 1943 and 1989 in eastern Nova Scotia. Generic and specific diagnoses are given, and the genus is inserted in Slater and Baranowski’s (1978) key to the genera of North American Nabidae. The geographical distribution and bionomics of the species are briefly discussed.

A gynandromorph of Rachispoda subpiligera (Malloch) is described. The specimen exhibits both bilateral and anterior/posterior division of male and female genitalic components. Abdominal segment 5 is male, segments 6 and 7 are bilaterally divided into male (right) and female (left) halves, and segments 8–11 are female. Comparison of male and female components supports the view that the large, asymmetrical sclerite posterior to sternite 5 in male Sphaeroceridae is synsternite 6 + 7. Circumversion of the genitalia, normally seen in male segments 8–11, is absent, although male components of segments 6 and 7 exhibit asymmetry normally associated with circumversion. This suggests that asymmetry of sternites 6 and 7 is a developmental process independent of circumversion, not a direct consequence of circumversion.

Eggs of western tent caterpillars hatch just as leaves of their food plants are developing. To determine the impact of asynchrony between leaf development and egg hatch during a year of peak density and the initiation of decline, egg masses were introduced to four study areas after the time of normal egg hatching. Survival of caterpillars was not significantly influenced by delays of 3–6 weeks in hatching. Populations composed primarily of introduced insects and control populations declined following the summer of the experiment. Although hatching of deployed eggs was delayed, caterpillar development during warmer temperatures later in the spring was sufficiently rapid that caterpillars from all groups reached the fifth instar by mid-June, and parasitization of caterpillars from control and experimental areas was similar. Tent caterpillar survival was apparently resilient to substantial delays in egg hatch which suggests that cyclic population declines are not likely to be associated with minor variation in the synchrony of leaf development and egg hatch.

The genus Parasimulium Malloch holds a position of special interest within the family Simuliidae. Not only is it the sister group to all remaining members of the family (Wood and Borkent 1982; Cume 1988), but the four described species of the genus are known only from northern California to Washington State. The genus was considered to be very rare until the rediscovery of a population of P. crosskeyi Peterson by Wood and Borkent (1982) in northern Oregon. Since then, the egg, first and second larval instars (Borkent and Wood 1986) of P. stonei and the nearly mature larva and pupa (Courtney 1986) of P. crosskeyi have been described. Larvae and pupae of P. crosskeyi have been collected from the hyporheic zone of a seep near a larger creek (Courtney 1986). The immatures were found among debris retained by a net held below the outlet while excavating the seep by hand. Finally, Currie and Walker (1992) have discovered fossil larval fragments of Parasimulium from Marion Lake, B.C., (50 km east of Vancouver) that were dated at 10 500 – 11 000 years before present and these represent the first records of the genus from Canada.