Female southern pine beetles, Dendroctonus frontalis Zimmermann, may propagate two species of symbiotic fungi in a prothoracic mycangium. Females can carry either Ceratocystiopsis ranaculosus Bridges and Perry or an unnamed basidiomycete or both; some carry no fungi. Thus, females can be categorized into one of four groups based on mycangial content. We examined size and lipid content of emerging brood adult females based on these mycangial fungal classes. Female beetles carrying the basidiomycete, either alone or in combination with C. ranaculosus, were larger, heavier, and contained more lipid than did females carrying only C. ranaculosus. Size and lipid content also varied by season, as did the number of females carrying different fungal combinations. Regression analysis showed that variation in the occurrence of the basidiomycete was significantly related to variation in averages of beetle size and lipid content measurements.

Ips mexicanus (Hopkins) and I. paraconfusus Lanier can transmit a frugal pathogen that causes pitch canker [Fusarium subglutinans (Wollenw, and Reink.) Nelson, Toussoun, andMarasas], a disease recently identified in Monterey pines (Pirns radiata D. Don) in California. In Santa Cruz County, F. subglutinans was recovered from Ips spp. that emerged from pitch canker-in fee ted P. radiata and were captured in multiple-funnel traps baited with racemic Ips spp. pheromones. Ips paraconfusus adults experimentally contaminated with propagules of the fungus transmitted it to seedlings and mature pines. Field transmission was demonstrated when cankers were produced following pheromone-induced beetle attacks on pines. Ips spp. inoculated F. subglutinans into pine slash, thus creating reservoirs of this fungus. Larvae, pupae, and young adults acquired the fungus when their parents introduced it into logs. Ips spp. progeny production and development were not significantly altered by the fungus. In proximity to other bark beetle-associated fungi, growth of F. subglutinans was reduced and patchy. A new association may be developing among native Ips spp. and F. subglutinans.

Sticky stovepipe traps, flight interception traps, and Lindgren multiple-funnel traps were baited with conifer monoterpenes and ethanol to capture conifer-feeding beetles and their associates. Of the more than 6000 beetles captured, 74.6% were caught by stovepipe traps, 14.8% by interception traps, and 10.7% by multiple-funnel traps. Dominant families were the Scolytidae (14.5% of all beetles captured), Elateridae (14.4%), Lampyridae (12.1%), Cerambycidae (12.0%), Cleridae (10.5%), Curculionidae (9.3%), Staphylinidae (4.0%), and Buprestidae (3.4%), with other families accounting for 19.8% of specimens captured. Conifer-feeding species in the families Buprestidae, Melandryidae, Cerambycidae, Scolytidae, and Curculionidae and their predators (Cleridae) were captured in greatest numbers by the sticky stovepipe traps; the interception traps generally captured the fewest specimens. The sticky stovepipe traps may be superior because they offer a distinct vertical silhouette to approaching insects.

The European spruce sawfly, Diprion hercyniae (Htg.), was first discovered in Canada in 1930 and in the next few years attained outbreak proportions in spruce forests over large areas in the Gaspé Peninsula and New Brunswick. The accidental introduction of a polyhedrosis in the early 1930’s was responsible for the rapid decline of the infestation, and under the influence of both disease and introduced parasites, densities throughout the range of the sawfly have been fluctuating at very low levels for the past 20 years. Population studies have been conducted on this insect in New Brunswick since 1938 and data are now available for 50 consecutive generations over a 25-year period. Morris’ key-factor approach, using parasites, disease and weather as the key factors, has been used in the analyses of the data. Although disease obscured the effect of other control factors, during high sawfly densities, larval parasites have been largely responsible for maintaining the low densities experienced in New Brunswick for the past 20 years. A pronounced change in the relative importance of the different parasite species and in the amount of cocoon predation attributable to small mammals and wireworms has occurred during the change from high to low host densities.

An overview of data from five research groups participating in a 3-year pilot test on the efficacy of foliar applications of Beauveria bassiana (Balsamo) Vuillemin for control of Colorado potato beetle, Leptinotarsa decemlineata (Say), populations in the northern United States is presented. Four treatments were used at each site: high and low B. bassiana dosages (5 × 1013 colony forming units (CFU) per hectare (ha) and 5 × 1012 CFU/ha), the recommended insecticide for each region, and an untreated check. The primary response variable was potato yield. For analyses considering test sites as replicates, during all 3 years the highest yields were produced in plots treated with insecticides. Within test sites, yields from plots receiving B. bassiana applications were greater than control plot yields in 8 of 24 trials but in only two of these instances, B. bassiana plot yields also did not differ from insecticide plot yields. Evaluating 1983 data from all states together, no differences were found between either high or low B. bassiana treatments and controls. The 1983 study design allowed no plot replication within states. In 1985, an altered plot design providing within-site replication demonstrated increased yield with increased dosage of B. bassiana when initial egg density was used as a covariate.

Potato yields greater than control plot yields were noted with a minimum of 5.39 and 6.62 × 1011 CFU/ha B. bassiana. The lowest B. bassiana concentration producing yields not significantly different from insecticide plot yields was 6.62 × 1012 CFU/ha (Rhode Island, 1984). Defoliation ratings did not differ between B. bassiana treatments and controls in 1984 and 1985, although variability was found between yields.

A faunal list of 362 sub-fossil Coleoptera obtained from 33 published and 24 unpublished sites of Pleistocene age in Canada and the neighbouring United States is given. A table indicates the distribution of families, with the number of species encountered, through discrete intervals of Pleistocene time. Seven species representing members of the Carabidae, Hydrophilidae, Staphylinidae, and Scolytidae have been used to illustrate distribution changes through the last interglacial/glacial/present interglacial cycle. The maximum distance so far recorded is a shift of over 9000 km for Anotylus gibbulus (Epp.), a staphylinid, found fossil in Toronto during the last interglacial, and today recorded only from Eurasia and Asia. A number of other species whose modern ranges are confined to northwestern North America have been found fossil in the Great Lakes – St. Lawrence region, over 4000 km distant. A similar shift is noted in species which today are found only in the eastern Canadian Arctic. Aspects of ice build up, marginal conditions outside the Laurentide Ice Sheet limits, Pleistocene climates, paleoecology, and sub-fossil insect localities are used to formulate hypotheses about three refugia around the perimeter of the Late Wisconsinan ice.

The effect of conservation and conventional tillage on carabid communities was compared using pitfall trapping in two commercial barley (Hordeum vulgare L.) fields located 4 km apart on similar soils. Carabid abundance was significantly higher under conventional tillage but abundances of individual species varied between the two fields. Agonum placidum Say and two Amara Bonelli species were more abundant at the conventional tillage farm whereas Pterostichus adstrictus Eschscholtz and three Bembidion Latreille species were significantly more abundant at the reduced tillage farm. Slightly more carabid species were collected in this latter field and species diversity and evenness were significantly higher.

In Rhodnius, a volatile substance produced by mating pairs is attractive to male insects. The pheromone acts also as a sexual stimulant; males respond in the absence of females by attempting copulation with other males. Air swept over mating pairs and conducted to a cage at a considerable distance proved to be highly attractive to males. Proximity of the sexes, without opportunity for actual contact, does not stimulate production of the pheromone. Since males and females will copulate only after a blood meal, feeding is a prerequisite to pheromone production. Also, unfed males will not respond to the attractant. Males of this nocturnal species were stimulated only in complete darkness.

As a result of alar tagging migrating specimens of the monarch butterfly (Danaus p. plexippus L.) in North America over a period of 25 years, it was possible to plot the migration routes establishing two large overwintering colonies, one located in California and the other in mountains of the Sierra Madré Occidentale in Mexico. Photographs of the two overwintering populations are presented together with release–recapture lines showing the direction of migration from breeding areas to the two overwintering sites. Data, presented for the first time, show the migration routes of the Western population from the breeding areas in the mountains and west of the mountains to California.

Schizocosa Chamberlin, 1904, with type-species Lycosa ocreata Hentz, 1844, comprises 20 species occurring in southern Canada, the U.S.A., and Mexico: S. ocreata (= Lycosa charonoides Montgomery, 1902, SYN. N.); S. crassipes (Walckenaer, 1837); S. floridana Bryant, 1934; S. saltatrix (Hentz, 1844); S. humilis (Banks, 1892) (= Lycosa episima Chamberlin, 1924, SYN. N.); S. duplex Chamberlin, 1925; S. salsa Barnes, 1953; S. bilineata (Emerton, 1885); S. segregata Gertsch and Wallace, 1937; S. aulonia Dondale, 1969; S. crassipalpata Roewer, 1951; S. mimula (Gertsch, 1934) (= Lycosa coahuilana Gertsch and Davis, 1940, SYN. N.); S. minnesotensis (Gertsch, 1934); S. retrorsa (Banks, 1911); S. avida (Walckenaer, 1837); S. maxima sp. n.; S. chiricahua sp. n.; S. cespitum sp. n.; S. communis (Emerton, 1885), comb. n. (= S. heasmani Dondale, 1969, SYN. N.); S. mccooki (Montgomery, 1904), comb. n. (= Lycosa pacifica Banks, 1904, SYN. N. = S. wasatchensis Chamberlin and Ivie, 1942, SYN. N).

Avicosa Chamberlin and Ivie, 1942 and Epihogna Roewer, 1960 are synonymized under Schizocosa. Fourteen of the species of Schizocosa are represented only in the southeastern United States, the northeastern U.S., and eastern Canada, or are widespread in the eastern half of the continent; three are represented only on the prairies, and the remainder in the Rockies or the Pacific coast.

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is a major worldwide pest of cruciferous vegetables (Talekar and Shelton 1993). Male and female adults of this species can be accurately identified by visible differences in their external genitalia. According to Robertson (1939), the sex of pupae can also be identified, but, in our experience, this approach is more difficult. For some types of research, determination of larval sex would be useful. For example, one could determine sex-specific responses of larvae to a treatment by observing mortality, development rate, or behavior of male and female larvae separately. In studies requiring hybrid mating between different strains of diamondback moth (Tabashnik et al. 1992), one could isolate groups of male larvae separately from female larvae to avoid mating within a strain. Some lepidopteran larvae can be sexed by the gonads being visible through the cuticle of the fifth abdominal segment or by the position of external pits marking the location of the genital discs in the eighth and ninth abdominal segments (Stehr 1987). But, because of their small size, it is not practical to sex diamondback moth larvae by external pits and we have found no studies in which male and female larvae were identified by gonadal form. Herein we report that third- and fourth-instar larvae of diamondback moth can be sexed efficiently and reliably.

The susceptibility of 31 species of agricultural insect pests representing 7 families of Lepidoptera, 3 of Diptera, and 3 of Coleoptera to the entomogenous nematodes Steinernema feltiae Filipjev and Heterorhabditis bacteriophora Poinar, were investigated in the laboratory. Of the 27 species found susceptible to S. feltiae, 19 are reported for the first time. Of the 21 species killed by H. bacteriophora, 15 are reported for the first time. The Lepidoptera as a group were highly susceptible to the nematodes. On the basis of larval mortality caused by the nematodes, of nematode reproduction in insect cadavers, and of the known economic importance and life histories of the test insects, S. feltiae was judged to warrant further research as a possible biological-control agent against Euxoa ochrogaster (Guenée), E. auxiliaris (Grote), Agrotis orthogonia (Morr.), Actebia fennica (Tauscher), Mamestra configurata Walker, Delia radicum (L.), D. antiqua (Meig.), and Zygogramma exclamationis (F.).

Choristoneura fumiferana (Clemens) and C. pinus pinus Freeman are redescribed, and the following five forms are described as new: C. biennis, British Columbia; C. occidentalis, Washington; C. orae, British Columbia; C. viridis, California, Oregon; C. pinus maritima, Pennsylvania, Massachusetts, New Jersey, Kentucky.

Nymphs and adults of Podisus maculiventris (Say), reared on four sizes (diet levels) of live larvae of Galleria mellonella (L.), captured prey, consumed food, and grew at rates varying with the size of larvae supplied. For nymphs, a direct linear relationship was obtained between rate of food consumption and daily growth and rate of food consumption and daily development. For adults, male and female, age did not affect food intake significantly, but for females alone, food intake differed significantly at different diet levels. A significant difference was also obtained for both sexes between body weight and diet level. Males and females lived longest on diet 1, apparently because of reduced metabolic activity.The number of eggs laid by each female corresponded to its food consumption for the first 35 days but decreased thereafter with age. The mean dry weights for fertile and infertile eggs at different diet levels did not differ significantly irrespective of the amount of food consumed by egg-laying females.For each nymph in each of instars 2 to 5 and for adults, the consumption quotient, an index of metabolic activity, increased as the rate of food consumption increased. For nymphs, the quotient decreased during ontogeny at each diet level, and for adults, decreased with age at diet levels 2, 3, and 4. The quotient remained constant for adults of both sexes at diet level 1.Results show that nymphs and adults of P. maculiventris can survive and mature satisfactorily for extended periods on small prey but needs larger prey to accelerate development, increase growth, and maintain a high reproductive potential.

Sweetman (1940) suggested that unfavourable spring weather is probably the most important natural check for the forest tent caterpillar, Malacosonza disstria Hbn. He observed that warm weather in April or early May that induces hatching, followed by a week or more of cool weather, frequently destroys the caterpillars. Blackman (1918), Tomlinson (1938), and Hodson (1941) have reported similar observations.

This is the third paper in a series dealing with investigations, initiated in 1956, to determine if the codling moth, Carpocapsa pomonella (L.), might be eradicated in the Okanagan and Similkameen Vallevs of British Columbia by the release of sexually sterile moths. In the first twoe papers exposure to heat (Proverbs and Newton, 1962) and to gamma radiation (Proverbs and Newton, 1962a) were examined as methods of inducing sexual sterility. Heat was not satisfactory. However, exposure of fully developed pupae to 40,000 rads of gamma radiation induced almost complete sexual sterility (used in the broad sense) in the male moth without causing undesirable side effects. The female was more easily sterilized than the male.

This paper describes a method of rearing the spruce budwom, Choristoneura fumiferana (Clem.) under laboratory conditions. The development of such a method has been necessary as a preliminary step in a program of investigations into the genetics of the spruce budworm. The method therefore attempts to satisfy primarily the requirements of genetical studies but, since these are as exacting as may be necessary for any biological investigation, a wider applicability may be anticipated.

Worker-male conflict in different bumble bee species is strongly associated with tendency, toward inbreeding. It is hypothesized that the major cost imposed by inbreeding arises from the production of diploid males in place of workers, during the early phases of colony development. The consequent dilution of the labour force slows down colony growth and leads to ultimate reduction in reproductive success. An experiment to test this hypothesis is described, using consanguineously mated queens of B. atratus Fkln. Colonies yielding a 1:1 mixture of males and workers grew significantly more slowly than normal all-worker producing colonies, providing support for the hypothesis.

Females of Monoctonus paulensis (Ashmead), a solitary parasitoid of aphids, generally select the relatively smaller over equally available larger instars of the pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphidoidea: Aphididae). Large hosts contain more resources for parasitoid development and hence have presumably higher quality; however, they require more time to subdue and are more likely to escape. We tested the hypothesis that a female’s choice among first (L1), second (L2), third (L3), and fourth (L4) instars of the pea aphid is based on the optimal balance between fitness costs in terms of time and fitness gains in terms of offspring number and size. Prepupal mortality did not vary with host instar, but pupal mortality was greater among parasitoids developing in L4 than in any younger instars. Offspring mortality was not influenced by clutch size in that mortality risk did not differ between parasitoids developing alone and counterparts developing in a clutch. The sex ratio, measured as proportion of daughters among offspring, was female-biased on all four host instars; the degree of bias increased from 0.70 (in L1) to 0.92 (in L4). Parasitoid body size was a function of aphid size at parasitism. Females were larger than males; the magnitude of the difference in body size was constant and independent of host and hence parasitoid size. A female’s potential fecundity as measured by the number of ovarial eggs at eclosion varied with her size and larval ontogeny. The four instars of the pea aphid were ranked in the order L1 > L2 > L3 > L4 both in terms of the number of offspring produced per encountered host and in terms of a female’s time costs; first instars are easier to handle and are more abundant in the field than older instars. The four host types were ranked in the order L2 > L3 > L1 > L4 in terms of the proportion and potential fecundity of daughters among offspring. The observed preference pattern (L1 > L2 > L3 > L4) suggests that, in choosing hosts, females of M. paulensis maximize the number of offspring per unit of search time rather than simply offspring quality.

That insect parasites regulate and, in the case of newly introduced species, sometimes reduce the average density of insect pests has led to an exmination of the properties of parasites in general. Consideration has been given to the manner in which parasites select hosts for oviposition and to the physiological and psychological basis of this selection. The distribution of parasite progeny among suitable hosts has been analysed in many cases, for the fewer the hostS that are superparasitized for any given number of parasite eggs laid the greater the efficiency of the parasite in reducing host density. It is obvious that before the factors of host selection and superparasitism become important in host-parasite interaction the parasite must find the host individuals. When the hosts are confined to a relatively small area the potential oviposition of the parasite, subject to discrimination among hosts and restraint in oviposition, often determines the level of parasitism. As distance between individuals of the host population becomes greater, however, it is necessary for the parasite to search the environment more extensively. Therefore, the ability of the parasite to find hosts is a factor of prime importance in determining its influence on the density of its host. The success with which a parasite discovers hosts in relation to host density is determined, of course, by several characteristics of the parasite species and by the modification of these characteristics through variations in the physical environment.