Laboratory studies of diapause induction in the horn fly Haematobia irritans irritans (L.) indicated that the incidence of diapause was unrelated to daylength or the number of day–night cycles. Transfer experiments were conducted to estimate the beginning and end of diapause sensitivity and the required number of days for diapause induction. On average, sensitivity was between the ages 0.10 and 0.82 on a physiological age scale of immature development. The number of days required for 50% diapause was estimated as 19.1 days. A model was developed relating the proportion of insects in diapause to the number of days spent in the interval 0.10–0.82. Additional experiments revealed that diapause in the puparia was related to the mean temperatures experienced by immatures during the interval of sensitivity. An equation relating the proportion in diapause to temperature was also developed and compared with the required day number model. Both models provided similar estimates of the proportion of horn flies entering diapause.

Results are presented for a 4-year (1986–1989) cytological survey of the Simulium venustum/verecundum complex on the Avalon Peninsula, Newfoundland, Canada. Based on 4578 larval identifications from 72 sites, six species in the S. venustum/verecundum complex were found: S. truncatum Lundström (= S. venustum EFG/C), S. venustum CC2, S. venustum CC3, S. venustum AC(gB), S. verecundum Stone and Jamnback (= S. verecundum AA), and S. rostratum Lundström (= S. verecundum ACD). The possibility that S. venustum A/C and S. venustum Say (= S. venustum CC) exist on the Avalon Peninsula in low numbers cannot be excluded, although this is doubtful. Discoveries of EFG/C and CC2 reciprocal sex exceptions support the hypothesis that exceptional individuals are the product of crossover. Cytological results confirm the supposition that S. truncatum, S. venustum CC2, S. venustum CC3, S. venustum AC(gB), S. verecundum AA, and S. rostratum are all distinct species. Results are interpreted within the broader geographic context of the S. venustum/verecundum complex. Three new cytotypes are recognized: one, from Quebec, we place under AC(gB); the other two, from the eastern United States, fall under CC2.

The structure of the parameres (lateral lobes) of aleocharine aedeagi was examined in detail, with special attention to the basal lineages. Paramere structure was compared in the context of a hypothesis of phylogeny of the basal lineages of the Aleocharinae and the Tachyporine Group of subfamilies. The ancestor of all contemporary aleocharines had parameres with the following characteristics: dorsobasal and ventrobasal lobes of more similar size than in extant higher aleocharines; dorsobasal lobe (condylite) continuous with distal lobe (not articulated); a striated velum (velar sac), extended from near the base of the dorsobasal lobe to near the apex of the distal lobe and derived from the dorsal surface of the distal lobe; distal arm entire, without articulations or independently movable parts; and four apical setae on the distal lobe, probably with the most apical and basal ones directed mediad and the two medial ones directed more-or-less laterad. In addition, each paramere was articulated with a separate condyle of the median lobe of the aedeagus near the middle of the condylite of the paramere, and the apices of the dorsobasal lobes of the two parameres articulated with each other substantially distal to the articulation with the median lobe of the aedeagus. The most parsimonious resolution of paramere evolution suggests that aleocharine parameres were derived from structures similar to those found in Trichophyinae, Phloeocharinae, and Olisthaerinae and that they are not de novo structures. Hypotheses about homologous regions between aleocharine parameres and those of these latter three groups are suggested.

Morphological, distributional, and habitat data are presented for North American species of the three genera of the subfamily Neomamersinae, Neomamersa Lundblad, 1953, Arizonacarus gen.nov., and Meramecia Cook, 1963. Neomamersa lundbladi lundbladi Cook, N. lundbladi paucipora Cook, and N. hexapora Cook are redescribed based on examination of types and newly collected specimens, and six new species of Neomamersa from the United States are described, namely N. boultoni sp.nov., N. psammicola sp.nov., N. californica sp.nov., N. chihuahua sp.nov., N. neomexicana sp.nov., and N. cramerae sp.nov. Arizonacarus chiricahuensis gen.nov., sp.nov. is described from the southwestern United States. Meramecia (Meramecia) anisitsipalpis (Cook), M. (Meramecia) perplexa (Cook), and M. (Meramecia) ocularis (Cook) are redescribed based on study of types and newly collected specimens, and M. (Meramecia) occidentalis sp.nov. is described from the western United States. Meramecia (Parameramecia) multipora subgen.nov., sp.nov. is also described from the southwestern United States. Revised diagnoses, keys, and distribution maps are presented for all North American taxa. Phylogenetic relationships of Neomamersinae are discussed, leading to the conclusion that comprehensive reassessment of the families Limnesiidae and Anisitsiellidae is warranted. Consideration of available phylogenetic and distributional data suggests that Neomamersinae originated in Gondwanaland before the separation of India from the rest of the southern supercontinent. Subsequently, the clade evolved and diversified extensively in South America. Neomamersinae apparently first entered North America either by crossing a "filter bridge" during late Cretaceous, Paleocene, or Miocene times or by traversing the corridor established with the formation of the Panamanian Isthmus during the late Pliocene. The group exhibits considerable taxonomic diversity in hyporheic and groundwater habitats in the United States, and the various species represent potentially useful indicators of water quality and the impact of environmental changes on freshwater communities.

An investigation into the use of thresholds based on Cabbage Looper Equivalents (CLE) was conducted on Brussels sprouts, Brassica oleracea var. gemmifera (L.), cv. Valiant, grown in Prince Edward Island in 1991 and 1992. The CLE model was used to equate foliage consumption by larvae of the imported cabbageworm, Pieris rapae (L.), the diamondback moth, Plutella xylostella (L.), and the cabbage looper, Trichoplusia ni (Hübner). Management strategies included the following: (1) an untreated check; applications of insecticides after thresholds of (2) 1.0 CLE; (3) 0.50 CLE; or (4) 0.25 CLE per plant were exceeded; (5) bi-weekly applications of insecticides; and (6) applications of insecticides according to the grower’s spray schedule.In 1991, the imported cabbageworm was the most abundant species in the complex attacking the crop and high yields were obtained in all treatments. However, in 1992, the diamondback moth was the principal species and significantly reduced marketable yields in all treatments. Use of CLE as a model for threshold determination in the crop of Brussels sprouts underestimated the potential of the diamondback moth for damage and resulted in improper timing of applications of insecticide for adequate control of the diamondback moth.

Two new species of metallic-green Coleophora are described from the Nearctic region: C. alabama Landry from coastal Alabama, U.S.A.; and C. mexicana Landry from the state of Tamaulipas, Mexico. Modifications to the key to adults of the Nearctic species of metallic-green Coleophora from Landry and Wright (1993) are provided to account for these new species. Larval host plants and natural history are unknown. Both species are tentatively placed in the ramitella group. Coleophora mayrella (Hübner), originally from the Old World but long established in North America, is recorded for the first time from South America (Chile and Argentina).

The contact toxicities of 11 insecticides were determined with a Potter spray tower using adults of crucifer flea beetles (Coleoptera: Chrysomelidae) collected from three locations over a 3-year period. Flea beetles collected from an experimental farm at London, Ontario, where no insecticides had been used, were compared with those from canola-growing areas near Saskatoon, Saskatchewan, and Winnipeg, Manitoba. Lindane, in a seed dressing, is widely used in both Saskatchewan and Manitoba whereas carbofuran, as in-furrow granules, has been more heavily used in Manitoba than in Saskatchewan. The flea beetles from Winnipeg were significantly less susceptible to all three carbamates tested (carbofuran, carbaryl, oxamyl) than those from Saskatoon or London. Both the Winnipeg and Saskatoon flea beetles were significantly less susceptible to methamidophos than the London population but not to the other organophosphates, the organochlorine (endosulfan), or the pyrethroids that were tested. These differences may indicate resistance in the Manitoba population, but this low level would not affect the efficacy of the currently recommended insecticides. The results emphasize the need to develop control strategies that will minimize the chances that the level of resistance will increase.

In laboratory wind tunnel studies, quiescent Korscheltellus gracilis (Grote) females initiated wing fanning as light intensity was reduced to 25–11 lx at the end of a 16-h, 450-lx photophase. Males downwind of a wing-fanning female initiated wing fanning, rapid walking, or both, and upwind flight toward the female typically ensued shortly thereafter. Wing-fanning females whose abdomens had been removed, and excised hind wings of females evoked the same male responses, but females whose hind wings had been removed evoked no male response. The sex pheromone of K. gracilis evidently is released from the female’s hind wings, a so far unique site of pheromone release in female Lepidoptera. The importance of this finding to understanding the mating system of hepialids and the ancestral form of pheromone release among the Lepidoptera is considered.

We monitored eclosion patterns of adult Coquillettidia perturbons (Walker) in the Minneapolis – St. Paul region of Minnesota directly using emergence traps (1983, 1984, and 1992), and indirectly using CO2-baited adult traps (1987–1992) and larval sampling (1988 and 1989). Most mosquitoes eclosed in a unimodal pulse during June although peak eclosion periods varied among years and sites. It required 26.6 ± 1.5 days for 90% of individual populations to eclose. Temporal abundances of host-seeking females also suggested unimodal eclosion with peaks typically occurring in June and July. Most larvae overwintered in the fourth instar and pupated in early summer, as expected from adult data. However, many larvae overwintered in the third instar and did not molt into the fourth until July, which was after most eclosion was completed. These individuals may eclose in autumn or may spend a second winter as larvae.

Adults and larvae of Eustilicus relictus sp.nov. are described from the Edwards Plateau of Texas. The species is brachypterous and lives in deep leaf litter. Morphological characters of both stages indicate that E. relictus belongs in its own group and has a near-basal phylogenetic position in the genus. I infer that the group to which E. relictus belongs was in the United States before formation of the dry belt which currently separates mesic areas of the United States and Mexico. All other species of Eustilicus in the United States belong to younger groups that spread north from Mexico much later.

The response of the western balsam bark beetle, Dryocoetes confusus Swaine, to subalpine firs, Abies lasiocarpa (Hook.) Nutt., baited with (±)-exo-brevicomin (EXOB) or 9:1 blends of EXOB and endo-brevicomin (ENDOB), in two chiral combinations: (+):(±) and (+):(+), was assessed in a heavily infested stand in British Columbia. Unbaited control trees were not attacked, and the proportion of mass-attacked baited trees was similar for all other treatments. However, trees baited with the (+):(+) blend had the highest number of attacks per square metre, and they were also surrounded by the most attacked trees. The (+):(±) blend was intermediate in attractancy, and (±)EXOB was the least attractive bait. Pheromone-based management of D. confusus infestations may be more effective with the 9:1 blend of (+)EXOB:(+)ENDOB than with the previously used (±)EXOB baits.

The pterin age-grading method was applied to natural populations of stable flies sampled for 3 years from diverse locations in Minnesota and Iowa. Significant differences were detected among years in mean degree-day ages per fly. Fly ages, in degree-day units, were exponentially distributed. A two-parameter Weibull distribution closely fit the fly survival distributions. Mean expectations of life did not differ significantly between males and females and were estimated to be 86.6 degree-days above a 6.5 °C threshold. Conventional age-grading techniques based on ovarian morphology applied to Iowa females showed that large fractions of the populations experienced delays in vitellogenesis. The reproductive rate, in terms of lifetime ovipositions, was less than the maximum sustainable rate suggested by ambient temperatures.

Salignus distinguendus tahoensis (Knight) is raised to species status. All published records of the name S. distinguendus (Reuter) from North America are in error and are correctly associated with the name S. tahoensis. A diagnosis and key are provided to distinguish S. tahoensis from the Palearctic S. distinguendus and S. duplicatus (Reuter). The male and female genitalia and distribution of S. tahoensis are illustrated. The relationship between Oreolygus Linnavuori, Orthops Fieber, Pinalitus Kelton, and Salignus is discussed.

Conioscinella zetterstedti Andersson, a Palaearctic chloropid fly with polymorphic wing reduction, is recorded for the first time from the Nearctic region. The known range of the species is also expanded in the Palaearctic region, with records from the Novosibirsk region of Russia. The male and female terminalia are described and illustrated. Although previously known only from supralittoral areas on the shores of the North and Baltic seas, collection data in the Nearctic and central Palaearctic regions indicate that C. zetterstedti may be abundant in various decay communities including peatlands, swamps, lake shore debris, mammal nests, forest leaf litter, and around the bases of vegetation.

Larvae of the Australian fossorial carabid Carenum anthracinum Macleay are described from reared material and compared with the reared larva of C. elegans Macleay and eight different unassociated larval types belonging to the complex. These larvae exhibit an extraordinary range of character states indicating clearly that their placement in the tribe Scaritini cannot be retained. An examination of adult characters and, in particular, the fore tibial dentition confirms that Carenum and allied genera form a separate tribe, the Carenini, which appears to be a sister group of the remaining Scaritini (including Clivinina).

The genus Parabrochymena Larivière is reviewed. Parahrochymna inbio and P. ruckesi are newly described. Parabrochymena barberi dituta (Ruckes) is given specific rank. Two synonymies are established: Brochymena aculeata Distant = P. haedula (Stål), Brochymena cuspidata Distant = P. haedula (Stål). A lectotype is designated for P. haedula (Stål). Species groups are characterized, and a key to all taxa is presented for the first time. As appropriate, for each species of Parabrochymena, the following are provided: citation of original description, synonymies, type material, description, geographical distribution, taxonomic comments, natural history, and illustrations of important structural characters. Choroiogical affinities are presented and systematic relationships are hypothesized. A biogeographic analysis of Parabrochymena and Brochymena Amyot and Audinet-Serville is also presented.

Four species of Cruciferae [canola species Brassica rapa L. and Brassica napus L., and mustard species Brassica juncea (L.) and Sinapis alba L.], and various cultivars of each species, were evaluated for susceptibilities to infestation by Delia spp. (Diptera: Anthomyiidae) under field conditions in central Alberta, Canada. Susceptibility was measured throughout the season by recording numbers of eggs of Delia spp. laid on or near individual plants, and at the end of the season by a semi-quantitative determination of injury inflicted by larvae on taproots. Differences in susceptibility occurred among and within canola and mustard species. Plants of B. rapa were most susceptible to Delia spp.; both mean eggs per plant and mean damage ratings per plant on B. rapa significantly exceeded those of all other species studied. Intermediate susceptibility was observed for plants of B. napus and B. juncea; plants of S. alba were least susceptible. In general, differences in susceptibility were greater among species than among cultivars within species. Root damage generally correlated with oviposition among and within species, suggesting that the mechanism of resistance by cruciferous species to infestation by Delia spp. is antixenosis or nonpreference. Results of this study indicate that canola growers in regions infested annually by high population densities of Delia spp. should seed B. napus or B. juncea rather than B. rapa. However, if a short growing season necessitates seeding B. rapa, then growers should select the more resistant cultivars of this species.

Spruce bud moth adults eclosed in mid-July and completed oviposition within a period of 2 weeks at 8- and 11-year-old white spruce plantations and at an old-field site in northern New Brunswick. Parasitism of bud moth eggs by Trichogramma sp. started less than 14 days after the beginning of adult bud moth eclosion and increased until the middle of August. The temporal patterns of egg parasitism and predation of viable bud moth eggs were similar in 1988 when most mortality occurred during the 2 weeks following the end of oviposition. At two sites studied in 1989, most parasitism occurred during the 4–5 weeks, and predation during the 1–3 weeks following the end of oviposition. Examination of temporal patterns of parasitoid eclosion and of the incidence of parasitism suggests that second-generation parasitoids attacked bud moth eggs at two of three sites. Depending on site and collection date, predators either showed a strong preference for unparasitized eggs or ate similar proportions of unparasitized and parasitized eggs. The incidence of egg parasitism and predation was not influenced by egg density in 1988. In 1989, a weak negative relationship between the number of eggs per cluster and the incidence of egg parasitism was not significant. However, a significant proportion of the variation in percentage egg parasitism was attributable to the interaction between egg density per shoot and collection date.

The life cycle of Strobilomyia appalachensis Michelsen, a maggot exploiting black spruce seed cones, was studied in two plantations in northern Ontario in 1987 and 1988, and two seed orchards in New Brunswick in 1991 and 1992. Oviposition by S. appalachensis occurs slightly later than the white spruce cone maggot, S. neanthracina Michelsen, relative to seed cone development; otherwise the life cycles of the two species are similar. Adults were trapped near host foliage in May and early June. Eggs were laid between the scales of seed cones during early June, starting when the scales on most cones were closed and ending 1 week after cones were fully pendant. Up to five eggs per cone were observed but single eggs were most common. The first larval molt occurred within the egg chorion and second-instar larvae emerged from the egg. Second-instar larvae were found in the cones during the 2nd and 3rd week of June, and third instars from the 3rd week of June until mid to late July. Larvae tunneled around the cone axis and destroyed an average of 60% of the total seed per cone before exiting and dropping to the soil. Larval drop occurred from late June to late July and was significantly correlated with periods of rainfall. Mature larvae moved into the duff and overwintered in the soil as pupae. Aspects of the maggot’s life history are discussed in relation to pest management strategies.

A study of different biometrie data of populations of Uroleucon (U.) picridis (F., 1775) sensu lato using canonical discriminant analysis resulted in the separation of two morphological groups. Exchange of host plants allowed us to conclude that the two groups correspond to two different species: Uroleucon (U.) picridis and Uroleucon (U.) mierae sp.nov. This latter species was described and a key to the identification of both species was given.