Adults of the rusty grain beetle, Cryptolestes ferrugineus (Stephens), were placed on the surface of grain in plastic cylinders. After 48 hours records were taken of the number passing through a perforated brass screen at the bottom of the cylinders and into petri dishes containing wheat inoculated with different species of fungi. More adults were found in dishes of spoiled grain containing a mixture of fungi than in empty (control) dishes or dishes with water. The largest number were found in dishes containing Penicillium corymbiferum and the second largest number in dishes with Scopulariopsis brevicaulis, Fusarium sp., and spoiled grain. The least number occurred in dishes with Streptomyces sp., uninfected wet grain, or dry grain. The response to fungi is probably induced by olfactory stimuli from volatile compounds in the fungi or by-products of fungi.

It has been shown by Farstad (1940) and Platt (1946, 1948) that resistance in wheat to the wheat stem sawfly, Cephus cinctus Nort., is positively correlated with solidness of stem. Under certain environmental conditions the resistant variety Rescue becomes susceptible to sawfly damage. The nature of this resistance is unknown, but a study of the nutritional requirements of C. cinctus may reveal it and perhaps assist in the development of new resistant varieties. The preliminary phases of this project were conducted with the following objectives: to studv the anatomy of the larval organs of ingestion and digestion; to determine the plant tissues ingested by the larva; and to study the hydrolytic enzymes present in feeding larvae.

The nesting behaviour of the euglossine bee Euplusia surinamensis was observed on the Osa Peninsula of Costa Rica. We found that female bees nest in aggregations, re-use old nests, will take over abandoned nests shortly after the original owner is removed, and will fight off invading bees which attempt to take over their nests. We suggest that the nesting aggregations give bees the opportunity to use old nests and take over partially provisioned nests if the original owner disappears. In this way bees are able to increase their rate of egg laying above that which would be possible with solitary nesting and de novo nest construction.

Sampling procedures for estimating within-tree populations of second-stage larvae (L2) of Matsucoccus feytaudi Duc., infesting maritime pine (Pinus pinaster Ait.), were investigated. These included random sampling without replacement, and systematic sampling with and without a linear model. The relative precision of the sampling was affected by the number, size, and bark thickness of the sample units. Because of symmetrical vertical distribution of within-tree populations, systematic sampling with a linear model did not increase precision when compared with simple systematic sampling. Sampling can be profitably reduced to below the crown portion of the bole, after removal of the part with either smooth or very thick and pyramidal bark. Counting L2 exuviae in the upper 10 cm of each 20-cm-long log, using one in every three logs, provided a relative precision of about 40%. The numbers of male M. feytaudi caught in sticky traps baited with 5 or 30 μg of synthetic pheromone were compared with the numbers of L2 estimated according to the sampling method previously developed. There was a significant positive correlation between number of scales caught and L2 estimates, at the level of individual trees for the lower dose lures, and at the level of groups of trees for the higher dose lures, used in 20-year-old stands. Large captures in younger, weakly infested stands were related to a possible immigration of flying scale insects.

A dual-choice behavioral bioassay and gas chromatography – electroantennogram detection (GC–EAD) were used to determine the effect of host terpenes and nonhost green-leaf volatiles (GLVs) on the oviposition preference of the spruce budworm, Choristoneura fumiferana (Clemens). Some emphasis was placed on assessing the ability of females to distinguish between enantiomers of chiral monoterpenes because (+)-α-pinene but not (–)-α-pinene or (±)-α-pinene had been shown previously to promote oviposition. Headspace volatiles from white spruce, Picea glauca (Moench) Voss (Pinaceae), and balsam fir, Abies balsamea (L.) Mill. (Pinaceae), were sampled using solid-phase microextraction and identified by gas chromatography – mass spectrometry with the aid of a chiral column. Females deposited significantly more egg masses on filter paper substrate treated with host monoterpenes than on controls. Contrary to expectation, substrates treated with several GLVs were also preferred over the controls. None of the GLVs or terpenes was deterrent. Females showed no significant ability in either the behavioral or the GC–EAD bioassays to distinguish between enantiomers of selected chiral monoterpenes, including α-pinene, in contrast to earlier findings. We conclude that host terpenes serve as general rather than host-specific oviposition stimuli for spruce budworm.

An olfactometer is described in which an attractive zone is established and maintained in a precisely determined location on the floor (or wall) of an observation chamber and also in the air adjacent to it. Insects must therefore manifest their normal behavior in finding their way to it. The attenuation of the attraction by "background odors" can be studied quantitatively.

The eggs of a queen bumblebee are undeveloped when the queen emerges in the spring from winter hibernation. After emergence, the eggs develop while the queen is feeding on available sources of nectar and pollen. It is generally assumed that physiological changes associated with egg development stimulate a queen to search for a nesting place and start a colony. However, there is little information available on the relationship between egg development and the colony-founding behavior of the bumblebee.

First instars of 93 North American species of mosquitoes are studied and 56 are illustrated, 41 for the first time. Generic differences are well marked in this instar and nearly all species are separable.

Two keys to the 11 North American genera are presented; the first is constructed to show similarities between first and later instars. Each genus is described and keyed to species, and notes are given on each species. A supplementary key to the species of the southeastern states is designed for the use of a binocular microscope with magnification up to 60 ×.

Specific and generic differences are as well marked in the first as in the fourth instar. Identifications are as easy or as difficult in the first as in the fourth instar, though usually based on different characters.

An expanded key to the North American species of Aedes, incorporating those previously treated by Bohart and by Price, is attempted. The key reveals several species complexes which have not been discerned from other stages of the life cycle, namely, Aedes canadensis, nigromaculis, punctor, stimulans infirmatus and trivittatus.

A key to the first instars of the 37 species of the world-wide Anophelinae is presented, on the basis of published descriptions and figures of the exotic species.

Podisus sagitta (Fab.) is a small- to medium-sized predatory stink bug, which is distributed from the southern United States into South America. The immature stages and both sexes of the adult insect from a laboratory strain are described and illustrated. Notes on the life history of P. sagitta also are given.

Dryness of either an insect's habitat or its food has often been reported as inducing diapause. This has been well substantiated in Pectinophora (8, 21, 22) and Loxostege (23). Also, a difference in body moisture between forms of the same species, in diapause and not in diapause, has been recorded in Leptinotarsa (9), Lucilia (11), and Carpocapsa (24), there being less water in the insects in diapause. It is significant, though, that in preparing for diapause Leptinotarsa achieves a reduction in moisture content, even when there is an abundance of water outside, by excretion (4).

We examine the implications for intercontinental dispersal of the extinct ant genus, Titanomyrma Archibald et al. (Hymenoptera: Formicidae: Formiciinae), following the discovery of its first fossil in Eocene temperate upland Canada. Modern Holarctic distributions of plants and animals were in part formed by dispersals across Late Cretaceous through early Eocene Arctic land bridges. Mild winters in a microthermal Arctic would allow taxa today restricted to the tropics by cold intolerance to cross, with episodic hyperthermal events allowing tropical taxa requiring hot climates to cross. Modern ants with the largest queens inhabit low latitudes of high temperature and mild coldest months, whereas those with smaller queens inhabit a wide variety of latitudes and climates. Gigantic and smaller formiciine ants (Titanomyrma and Formicium Westwood) are known from Europe and North America in the Eocene. The new Canadian Titanomyrma inhabited a cooler upland. It is incomplete, indistinctly preserved, and distorted in fossilisation, and so we do not assign it to a species or erect a new one for it. The true size of this fossil is unclear by this distortion: small size would support gigantism in Titanomyrma requiring hot climates and dispersal during hyperthermals; if it was large, it may have been cold-winter intolerant and able to have crossed during any time when the land bridge was present.

A study was conducted in Butte County of western South Dakota to determine the relationships between habitat characteristics and spatial and temporal changes in community structure of grasshoppers on mixed-grass rangeland. Detrended correspondence analysis (DCA) of 29 undisturbed grasshopper communities and correlation analysis of DCA axis values and habitat variables denned specific spatial gradients underlying the community structure of grasshoppers. Results indicated that grasshopper communities changed along a primary gradient of percentage of coverage of grasses, particularly Buchloe dactyloides (Nutt.) Engelm., and a secondary gradient of percentage composition of clay and sand in the soil.

DCA of 24 grasshopper communities sampled in 1986 and 1987, multiple regression analysis, and factor analysis were used to determine the relationships between specific habitat characteristics and changes in communities of grasshoppers treated with either a nonselective insecticidal spray (malathion) or a selective insecticidal bait (bran bait with carbaryl). Results indicated that between-year change in community composition, or the difference between post-treatment communities in 1986 and 1987, was positively correlated with percentage of coverage of total grasses and forbs. Community malleability, defined as the tendency of a community to return to its predisturbed state, was greater in habitats with high coverages of Agropyron smithii Rydb. and Carex spp., low coverage of Bouteloua gracilis (H.B.K.) Lag. ex Steud., and low species richness of grasses. Our results emphasize the importance of habitat characteristics in structuring undisturbed grasshopper communities and in community change after perturbation with insecticides.

The morphology of haemocytes of Blaberus giganteus (L.) was studied in vivo in adult insects, and in stained films of blood from all stages. The study included the measurement of cells and the application of several histochemical tests. It was concluded that four categories of haemocytes exist, prohaemocytes, plasmatocytes, granular haemocytes, and spherule cells, and that the last two categories are closely related, both having the capacity to concentrate neutral mucopolysaccharides in their cytoplasm. Criteria for separating the categories are given.

The frequency of insemination of females in laboratory swarms of Chironomus riparius Meigen was investigated using autoradiographic techniques. In swarms in which the sexes were nearly equally represented the majority of females were invariably inseminated. The frequency of inseminations for a given population of males declined with aging. There was variation among individual males in the numbers of females inseminated and the timing of inseminations in a succession of eocrepuscular swarms. Unmated females appeared to be receptive to insemination throughout most of their adult life. Insemination or injection of extracts of males rendered the females unreceptive to subsequent inseminations. Unmated females held in cages for longer than 48 hr were found to resorb the eggs in one of their ovaries.

Field observations of Rhagoletis pomonella (Walsh) adults on apple and hawthorn trees revealed that mating encounters occur on leaves in early-season and shift to fruit with the onset of oviposition. Most matings on leaves are initiated from a male frontal approach to the female and most of those on fruit from a rear approach while the female is engaged in some phase of oviposition behavior. This suggests that matings on fruit may be forced matings with unreceptive females.

Females of Alydus eurinus (Say) release an attractant pheromone from their metathoracic scent gland. Conspecific males and, to a lesser extent, females and nymphs were attracted to blends containing the female-specific essential pheromone components 2-methylbutyl butyrate and (E)-2-methyl-2-butenyl butyrate, whereas individuals of Alydus pilosulus Herrick-Schaeffer were not attracted. When attacked, however, alydid adults emit chemicals for defense—butyric and hexanoic acids in A. eurinus—from the metathoracic scent glands. Mimicry is actually the first line of defense for most broad-headed bugs, including the common North American species studied here, whose nymphs are remarkable ant mimics and whose adults strongly resemble spider wasps (Hymenoptera: Pompilidae). The possibility that disparate heteropterans (Hemiptera) produce sexual pheromones in their metathoracic scent glands must be considered in future pheromone research on heteropterans, especially for species with the specialized lines of defense indicated by aposematism or mimicry.

Cohort life tables are seen to provide the basis for an analytic and insightful approach to the rational management of crop pests. A life table is presented for a typical planting of early market cabbage, and dx values appraised in the light of potential dollar revenues.

Capacity to adjust to variable resources of food is a useful criterion for assessing the regulatory influence of predators on the population of prey. Anatis mali Auct. was better adapted than Coleomegilla maculata lengi Timberlake to tolerate a shortage of food. When the food supply was increased, survival and adult weight increased in both species – adult weight to a much greater extent in A. mali than in C. maculata, and developmental time decreased in A. mali, but was unchanged in C. maculata. C. maculata was better able to withstand regularly occurring periods of intermittent feeding than a shortage near the end of its development.

The conversion ratio of third-instar A. mali larvae and the growth rate of C. maculata larvae were higher when individuals were fed on Acyrthosiphon pisum (Harr.) than on Rhopalosiphum maidis (Fitch). Between the minimum food requirement and the maximum quantity eaten, the conversion ratio of A. mali decreased whereas that of C. maculata remained constant except at the highest quantities of food where the rate of intake increased and the ratio decreased. Relative food intake rate is an accurate criterion for comparing stages and species of predators that are fed on various foods.

A review of the Nearctic genera and Canadian and Alaskan species of the Ocalea group is presented. Ten genera are treated, with five erected as new: Alfocalea Klimaszewski gen. nov. (type species: A. montana Klimaszewski sp. nov.), Betocalea Klimaszewski gen. nov. (type species: B. pacifica Klimaszewski sp. nov.), Gennadota Casey (reinstated), Longipeltina Bernhauer, Megocalea Klimaszewski gen. nov. (type species: M. lemieuxi Klimaszewski sp. nov.), Metocalea Klimaszewski gen. nov. (type species: M. lindgreni Klimaszewski sp. nov.), Neoisoglossa (Casey) (nomen novum), Neothetalia Klimaszewski gen. nov. (type species: N. nimia (Casey)), Ocalea Erichson (restricted definition), and Parocalea Bernhauer. Twenty-four species of the Ocalea group are here recognized in the Nearctic region, fourteen of which occur in Canada. Six new species are described from western Canada and Alaska: Neothetalia smetanai Klimaszewski sp. nov. (Canada: British Columbia), Neothetalia canadiana Klimaszewski sp. nov. (Canada: British Columbia, Yukon Territory; United States: Alaska), Betocalea pacifica (Canada: British Columbia), Alfocalea montana (Canada: Alberta, British Columbia), Metocalea lindgreni (Canada: British Columbia), and Megocalea lemieuxi (Canada: British Columbia). The first record of Neoisoglossa agnita (Casey) in Alberta is provided. Two nominal species, Atheta (Athetalia) bicarniceps Casey (= Neoisoglossa) and Isoglossa grandicollis (Casey) (= Neoisoglossa), are here synonymized with Neoisoglossa arcuata (Casey). Aleochara pallitarsis Kirby has been transferred to the genus Neothetalia and is newly recorded from Alaska and British Columbia. Ocalea columbiana Klimaszewski has been transferred to Neothetalia and is newly recorded from Alaska. Neothetalia pallitarsis was formerly recorded from an unknown locality in North America and Neothetalia columbiana from the Carmanah Valley on Vancouver Island. Neothetalia nimia is newly recorded from Alaska. A new generic classification is proposed to accommodate species of the Nearctic Ocalea group. New data are provided on the systematics, relationships, bionomics, and distribution of the Nearctic species and genera of America north of Mexico. Diagnoses, colour images of entire bodies, and line illustrations of genital features are provided for those Canadian and Alaskan species that were not formerly illustrated, and their collection localities are plotted on maps. A key to Nearctic genera of the Ocalea group and the species occurring in Canada and Alaska is presented. The lectotypes have been designated for the following nominal species because the original series consisted of syntypes or represented mixed species or both sexes but with males bearing a better diagnostic set of characters: Aleochara picata Stephens (= Ocalea), Atheta (Athetalia) bicarniceps, Atheta (Athetalia) nimia Casey (= Neothetalia), Atheta (Athetalia) repensa Casey (= Neoisoglossa), Isoglossa arcuata Casey (= Neoisoglossa), Ocalea agnita Casey (= Neoisoglossa), Ocalea franciscana Casey (= Neoisoglossa), Ocalea fusca Fenyes (= Neoisoglossa), Ocalea grandicollis Casey (= Neoisoglossa), Pyroglossa grossa Bernhauer, Rheobioma disjuncta Casey (= Neoisoglossa), Rheobioma marcida Casey (= Neoisoglossa), and Rheobioma terrena Casey (= Neoisoglossa).

We describe the calling posture of the brown spruce longhorn beetle, Tetropium fuscum (F.), and demonstrate, using solid-phase micro-extraction and gas chromatography – mass spectrometry, that this posture is positively correlated with the release of fuscumol, a male-produced long-range pheromone. The posture is observed only in males and is characterized by an extension of the legs that raises the body entirely off the substrate at an angle of approximately 10°, with the posterior end higher than the head. Characterization of the calling posture is a useful diagnostic tool for future research on the reproductive biology of T. fuscum, since a simple visual assessment can be used instead of chemical analysis to determine when males are emitting fuscumol. In addition, we demonstrate that the presence of conspecific males stimulates calling behaviour in T. fuscum. This study contributes much-needed data on the biology and mating behavior of this invasive wood-boring species.