The biogeography of 171 North American species of Euxoa (Lepidoptera: Noctuidae) is reviewed. For biogeographical analysis, species are arranged in groups according to habitat; these are 62 aridland species, 69 forest species, 19 widespread species, and 21 species with special or unknown habitat requirements. Aridland species are distributed primarily in grassland areas in the Great Plains and in sagebrush areas or piñon–juniper woodland in the intermontane region. Ranges in these two regions are connected in arid corridors through the Rocky Mountain region. Forest species in western North America are arranged in two groups: those that occur in both conifer forests and piñon–juniper woodland (17 species), and those that occur only in conifer forests (40 species). Species in the former category occur throughout the mountain ranges of the west including those of the Great Basin wherever suitable habitat occurs. Those of the latter category occur in conifer forests on mountain ranges around the Great Basin but do not occur in the Great Basin, even in mountain ranges that support suitable habitat. Most forest species that occur in the Rocky Mountain region also occur in disjunct woodland areas in the Great Plains.

The effect of Wisconsinan glaciation on the biogeographic regions of western North America is reconstructed from a review of fossil pollen and plant macrofossil studies. From this synthesis it is suggested that during the Wisconsinan glacial maximum, forest species were widely distributed in the Great Plains south of the Laurentian ice sheet, and at low elevations in the Sierra Nevada and Rocky Mountain regions. Piñon–juniper woodland species were widespread in the Great Plains. Forest species that do not occur in piñon–juniper woodland were distributed around the Great Basin but were prevented from reaching suitable habitat in mountain ranges within the Basin by unsuitable habitat in the intervening lowlands. The ranges of aridland species were greatly reduced during Wisconsinan time, particularly in the Great Plains. Aridland corridors through the Rocky Mountains were eliminated during the Wisconsinan glacial maximum.

The possibility of speciation during Wisconsinan time is reviewed. Although the distribution of many sister-species are what would be expected from speciation during the Wisconsinan, the distributions may reflect allopatric distributions during Wisconsinan time and not speciation.

Bacillus thuringiensis var. israelensis (serotype H-14) and B. sphaericus strain 1593 were tested against Aedes stimulons larvae in the laboratory and in 38-cm-diam, open-ended cylinders embedded in the bottom detritus of a woodland pool. Estimates of LC50 were lower against fourth instars in the field at a mean temperature of 15.9 °C than in the laboratory at 21.1 °C. The greater efficacy in the field was attributed to high daytime water temperatures (mean 20.5 °C) following treatment and exposure of the larvae to substantially greater amounts of toxic material in a larger volume of water than in the laboratory. The regression of probit on log10 concentration was not linear over the entire range of mortality caused by B. sphaericus, increasing the difficulty of estimation of LC values. Bacillus sphaericus was significantly less active than B. thuringiensis.

Leptocera (Thoracochaeta Duda), a subgenus of sphaerocerid flies associated with marine supralittoral habitats, is revised for the Nearctic Region. Keys are provided for separation of the nine Nearctic species. L. (T.) teskeyi, L. (T.) flaminuta, L. (T.) calminuta, and L. (T.) bajaminuta are described as new and L. (T.) zosterae is recorded from the Nearctic for the first time. The larvae of three species (zosterae, seticosta, and brachystoma) are described.

Yellowjackets (Vespidae: Vespula and Dolichovespula spp.) are painfully familar to most people. Many of these wasps are scavengers and are readily attracted to foodstuffs or food wastes. They also frequently nest in and around human habitations. These insects are generally considered of significant medical importance because of the allergic reaction in some people following a sting. Yellowjacket abatement programs have been conducted in many parts of the United States, usually associated with high wasp densities in orchards or recreation areas (McDonald et al. 1976).

Spores of the microsporidium Pleistophora schubergi were fed to second- and fifth-instar larvae of the spruce budworm, Choristoneura fumiferana. A treatment of 2 × 108 spores applied to the surface of the host's diet resulted in 100% mortality to second- and 60% to fifth-instar larvae. Suceptibility of the host to the parasite decreased as the larvae became older. Other effects on host development were not significant at the dosages tested.

Diapause development in Culex tarsalis Coquillett has been characterized by reduced blood-feeding to complete termination of ovariole development at or before stage IIa (Bennington et al. 1958; Schaefer and Washino 1970; Schaefer et al. 1971; Bellamy and Corbet 1973; Mitchell 1979). The role that diapausing Culex species have in overwintering arboviruses has been examined (Eldridge 1966, 1968; Eldridge et al. 1972; Reeves 1974; Eldridge and Bailey 1979; Mitchell 1979). Gonotrophic dissociation and its implications for survival of the vector and virus has been reviewed by Washino (1977). Eldridge (1966) indicated gonotrophic dissociation was possible in Culex pipiens L. incubated at low temperature and short daylength and later reported failure of ovarioles of prehibernating C. pipiens to mature following a blood meal (Eldridge and Bailey 1979). Eldridge et al. (1972) reported that Culex restuans Theobald exhibited gonotrophic dissociation in response to conditioning by short daylength and low temperature. Mitchell (1981) has reported blood-feeding and gonotrophic dissociation in a significant portion of diapausing Culex tarsalis from Colorado, when females were kept at 15°C and at short daylength conditions.

Since its initial introduction into North America (Saunders 1916) the European skipper Thymelicus lineola (Ochs.) has been found attacking timothy grass throughout much of eastern Canada and the United States reaching pest status in Ontario (Arthur 1966), Prince Edward Island (Thompson 1977), and Quebec (Doyle and Richard 1971; McNeil et al. 1975). Bucher and Arthur (1961) examined skipper larvae, collected near Princeville, Ontario, for naturally occurring pathogens and reported the presence of a nuclear polyhedrosis virus, a cytoplasmic polyhedrosis gut virus, and a spore forming bacterium. They stated that such pathogens represented a possible means of biological control if the skipper became economically important. An epizootic caused by an NPV in dense skipper populations near Normandin, Quebec (Smirnoff 1974), led to a series of experiments evaluating its efficacy as a microbial insecticide (Smirnoff et al. 1976; Duchesne 1980), its long term impact on the population dynamics of T. lineola (Duchesne 1980), and its possible effects on non-target organisms (Smirnoff et al. 1979).

Bioassays of Bacillus thuringiensis (Bt.) are commonly performed by applying a serial dilution of the test sample to either foliage or artificial diet (Burges and Thompson 1971). In these assays the ingested dose is not measured directly, but is assumed to be proportional to the concentration of the sample applied to the diet. This assumption is valid only if the total amount of food ingested during the experiment is the same at all dosage levels. However, this assumption may not be true because Bt. inhibits feeding of some lepidoptera larvae (Burges and Thompson 1971). Furthermore, artificial diets usually contain nutrients and possibly antimicrobial agents which may interact with Bt.