The world species of Urolepis Walker are reviewed and a key is given to differentiate females of Urolepis singularis (Ashmead) and males and females of Urolepis maritima (Walker) and Urolepis rufipes (Ashmead). Lectotypes are designated for U. rufipes and U. singularis. Biological literature relating to parasitism of house flies and stable flies by U. maritima and U. rufipes is summarized, and known hosts of the three species and collection records within the Nearctic region are given. Urolepis maritima is recorded for the first time from the Nearctic region, and U. rufipes is confirmed from northern Europe (Denmark and Germany).

The North American species of Lauxania Latreille are revised. The genus contains five Nearctic species: L. albiseta Coquillett, L. glabrifronssp.nov., L. kafaristasp.nov., L. nigrimana Coquillett, and L. shewellisp.nov. All Nearctic species are illustrated and keyed. Consistent genitalic differences between Nearctic and Palaearctic specimens of the species usually identified as Lauxania cylindricornis (Fabricius) justify the recognition of the Nearctic specimens as a distinct species (L. shewelli). The male genitalia of Lauxania represent two types: the apparently plesiomorphic type has a simple rodlike phallapodeme, membranous phallus, and pointed unbranched postgonites; the apomorphic type has the phallapodeme expanded into a sclerotized hood surrounding the base of the phallus, a convoluted sclerotized phallus, and branched postgonites. These two genitalic types also occur in the related genus Calliopum Strand, which provides strong evidence that these genera, as currently recognized, may not be monophyletic relative to one another.

New-world leafhoppers with strongly flattened heads are here assigned to three tribes: Deltocephalini (six genera), Dorycephalini (two genera), and Hecalini (seven genera). Revised keys are presented to the new-world genera, and 44 new-world species of the Nearctic genera Attenuipyga Oman (Dorycephalini) and Neohecalus Linnavuori, the Holarctic genera Hecalus Stål and Memnonia Ball, and the widespread new-world genus Spangbergiella Signoret (Hecalini). In Dorycephalini, Attenuipyga (with subgenus Dorycara Emeljanov, stat.nov.) has nine species, including Attenuipyga (s.s.) joyceaesp.nov. from Manitoba and Dorycephalus sinuatus Beamer, 1942b = Dorycephalus minor Osborn, 1920, syn.nov. In Hecalini, 10 species in Hecalus, 3 in Neohecalus, and 15 in Memnonia are recognized, including 20 species formerly in Parabolocratus Fieber, plus Hecalus finnamoreisp.nov., Neohecalus magnificussp.nov., Memnonia anthalopussp.nov., Memnonia maiasp.nov., and Memnonia panzerisp.nov. from the northern prairies and Memnonia leptaleasp.nov. from the Gulf states. Parabolocratus continuus DeLong, 1938 and Parabolocratus planus Shaw, 1932 are reduced to subspecific status in Hecalus montanus, and three names are synonymized: Parabolocratus inflatus DeLong, 1938 = Hecalus montanus (Ball, 1900); Parabolocratus rotundus DeLong, 1938 = Hecalus major (Osborn, 1915); and Parabolocratus elongatus DeLong, 1938 = Memnonia grandis (Shaw, 1932) syn.nov.

A larval population of spruce budworm, Choristoneura fumiferana (Clemens), was monitored for 5 d following aerial application of a commercial formulation of Bacillus thuringiensis Berliner subsp. kurstaki to investigate dose acquisition and expression (larval mortality, recovery, feeding, and growth) in relation to spray deposition and persistence of spray deposits. The main objective was to test if previous laboratory observations on how B. thuringiensis affects feeding and dose ingestion by spruce budworm larvae hold true under field conditions. About 40% of the treated population ingested a lethal dose within 1 d after spray application. Lethally dosed larvae died without further feeding upon transfer from treated foliage to (untreated) artificial diet. Resumption of feeding by larvae that survived the treatment was delayed relative to larvae from the control population during 3 d following spray application; during that time, normal feeding activity and larval weight gain were suppressed. Inhibited feeding by survivors appeared to prevent further dose uptake because the proportion of lethally dosed larvae in daily collections did not increase despite significant residual spray deposits in budworm feeding sites. Restoration of "normal" recovery times by the fourth day coincided with a 65–85% reduction in persistence of the pathogen on the foliage and did not result in further lethal dose acquisition, as treatment-induced mortality dropped to about 20% on the 4th and 5th days. The observations are consistent with previous laboratory observations of how B. thuringiensis affects larval feeding and with the hypothesis that feeding inhibition may be a limiting factor in the acquisition of a lethal dose.

Esterase banding patterns in native polyacrylamide gel electrophoresis, squash silver leaf (SSL) induction, and tomato yellow leaf curl begomovirus-Sardinia (TYLCV-Sar) transmission capability were investigated to evaluate variations among populations of Bemisia tabaci (Gennadius) from Italy and to relate their distribution to their geographic origin. Adults of the B biotype, adults of the Q-like biotype (which is similar to a Spanish biotype), and adults without esterase bands were found. The B biotype has been found in Italy since 1989. Two populations, including mainly B and Q-like biotypes, showed similar TYLCV-Sar transmission efficiency, independent of esterase banding pattern. Only populations from Liguria and Sardinia, which contained almost exclusively B-biotype individuals, were able to induce SSL. We observed that adults of the B biotype are widespread in greenhouses of northern Italy and Sardinia, whereas those of the Q-like biotype are present only in fields of southern Italy. These results suggest that the B biotype of B. tabaci was introduced into Italy likely while trading ornamental plants, whereas the Q-like biotype is native to the Mediterranean region.

Three white spruces, Picea glauca (Moench) Voss (30–35 cm diameter at breast height), felled in central Alberta, were colonized by Ips perturbatus (Eichhoff) beginning in late May 1999. The mean (±SE) density of breeding galleries on the trees was 217 ± 23/m2 (n = 30). Harem size ranged from one to four females per gallery, with a mean of 2.1 ± 0.6 (n = 90). Tunnel excavation and oviposition occurred primarily during the first 3 weeks after gallery initiation. Individual females laid 48.9 ± 2.5 eggs (n = 30) in galleries that reached 10.0 ± 0.3 cm in length (n = 45). Males assisted their mates by removing frass and woody debris from the tunnels. Males remained in their galleries for at least 1 week, although there was gradual attrition such that < 15% of males remained after 6 weeks. Large males abandoned their galleries sooner than small males. In contrast, females were present in almost half of the oviposition tunnels examined after 6 weeks, and there was no significant relationship between female size and residence time. Mortality from egg to adult was high (98%) during this 1-year study, likely a result of the intense crowding of galleries. Adult offspring were found beneath the bark in mid-July, although the main emergence did not begin until mid-September. Because such late emergence would be too late for these individuals to reproduce before winter, I conclude that I. perturbatus has only one generation per year in central Alberta.

Cohorts of Pieris rapae (L.) (Lepidoptera: Pieridae) were reared at different temperatures on three substrates: plants in growth chambers, plants in field cages, and artificial medium. Pupal weight and larval development times were measured. The data were analyzed to determine the effect of temporal changes in substrate on pupal weight. When cohorts were reared on whole plants, average pupal weight declined with increasing time to pupation. For cohorts on potted plants in growth chambers, the rate of decline decreased as temperature increased from 15 to 27 °C. But, for cohorts on plants in field cages, the rate of decline increased as temperature increased from 16 to 25 °C. We speculate that the former trend resulted from plant deterioration, especially at low temperatures, and the latter from larval competition at high temperatures. When larvae were reared on potted plants to the late II or early III instar and then transferred to artificial medium, deterioration of the medium at temperatures below 20 and above 27 °C caused pupal weight to decline significantly with increasing time to pupation, whereas between 20 and 27 °C, pupal weight was constant or increased with increasing time to pupation. Development times of larvae from cohorts reared on plants in growth chambers showed no consistent differences from those of larvae from cohorts reared on artificial medium, at any temperature (overall averages: 187 and 184 day-degrees above 10 °C, on plants versus medium). Pupal weights are determined by the ratio of growth rate to development rate (Appendix). Therefore, the observed differences in pupal weight reflect differences in growth rates rather than differences in development rates. The results show that, depending on temperature, substrate deterioration may seriously affect laboratory studies of herbivore growth and that there are important interactions between temperature and host-plant growth conditions that may make extrapolation of laboratory estimates of herbivore growth to field conditions tenuous.