Body size and mass variation of queen bumble bees (Bombus Latr. spp.) were analyzed in relationship to hibernation survival and optimal body size. Body mass and size (measured by radial cell length) were significantly correlated in six of eight species. Also, spring queens of B. occidentalis Greene were, on average, significantly larger yet lighter than young fall queens. These observations were consistent with weight loss known to occur during hibernation coupled with greater mortality of small queens over the winter. Thus large queens may be at an advantage for this and other reasons (e.g. foraging efficiency, usurpation). However, an optimality model showed that an intermediate body size was optimal if the reproductive success of a colony (foundress queen and workers) was considered. The assumptions were that fitness did not increase linearly with body size but was a convex function, and that colonies only had a fixed amount of energy to invest in reproductive offspring leading to a trade-off between size and number.

The larvae of the European pine shoot moth, Rhyacionia buoliana (Schiff.), feed on several species of hard pines, of which the most economically important are red pine, Pinus resinosa Ait., and Scots pine, Pinus sylvestris L. Approximately one hundred million trees of each species mere planted in southern Ontario since 1905, most of them since 1925. Many pure and mixed stands are now infested by R. buoliana which has no apparent preference for either host tree.

Studies on the biology of Encarsia pergandiella Howard, a solitary, arrhenotokous endoparasite, revealed that fertilized eggs, which give rise to females, are deposited in whitefly nymphs preferably in second, third or fourth instar, while unfertilized eggs, which give rise to males, are deposited in Encarsia larvae at whose expense they develop. The parasite adults were observed to feed on body fluids of whitefly nymphs. Both sexes have a pupal and three larval stages, and development from egg to adult at approximately 75° F. takes 15 days for the females and 13 to 14 days for the males. Mean longevity of the females at constant and fluctuating temperatures was studied. Actual mean fecundity at 75 ± 4° F. was 48.5 eggs per female, all of which were deposited during the first 70% of her life, provided hosts were abundant. Field observations revealed that E. pergandiella was present throughout the year, reaching highest numbers in the spring and summer. The parasite does not have an obligatory period of dormancy for all of its individuals. E. pergandiella was not able to prevent whiteflies from causing heavy damage to plants. The reason may be in the discrepancy between the rate of increase of the whitefly and the parasite.

This paper deals with the orientation reactions exhibited by larvae and adults of the spruce budworm, Choristoneura fumiferana (Clemens), (12) in response to stimulation by light. The insect is an important pest of the coniferous trees, Abies balsamea Mill, and Picea spp., which compromise the pulpwood stands of the forests of northeastern North America. Hence, at present, it is the subject of many investigations. The work reported here is part of an investigation designed to provide data for the development of studies of the effects of weather and climate upon the spruce budworm.

A new species of sarcophagid, Colcondamyia auditrix, is described, which locates its cicada host by sound. The fly was shown to respond to the mating song of the male cicada, and the majority of parasitized cicadas were male. Parasitism of females occasionally occurs when they are attracted to males simultaneously with the parasite. Levels of parasitism varied from 18.6% in 1962 to 0.2% in 1967 to 14.1% in 1973. Male cicadas lost their sound producing capability following parasitization, rendering them inaccessible to further female flies and thus apparently preventing multiple parasitism.

Field, glasshouse, and laboratory tests showed that deposits of polyhedra of the nuclear polyhedrosis virus of the cabbage looper, Trichoplusia ni (Hübner), on foliage are practically non-infective after a 1-month exposure to weathering. Inactivation by sunlight appeared to be more important than removal by washing by rain in causing this loss of activity. The virus was readily inactivated by exposure to ultraviolet light. Virus exposed in aqueous suspensions of polyhedra or in wetted deposits was inactivated by shorter exposures than was virus in dry deposits of polyhedra.

The effects of fiood od the fecundity and longevity of the adults of hymenopterous parasites vary remarkably, not only between species that are host feeders and those that are not host feeders, but also within these groups. It is known, for example, that the females of Itoplectis conquisitor (Say) develop only few eggs without feeding on body fluids of their host. In the present investigations it is shown that the females of Scambus buolianae (Htg.) are not able to deposit any eggs without first feeding on the tissues of their host. Such information is important for the successful establishment of newly-imported parasites.

Effects of temperature and resin on hatch of mountain pine beetle eggs were investigated. Per cent hatch was related to total degree-hours above 40°F, the average being 5113 for 50% hatch under field conditions. Average supercooling point was 1.3°F. Higher temperatures in the freezing range were lethal with long exposure. Atmosphere saturated with volatiles from liquid resin had very little effect on egg hatch, but direct contact with liquid resin greatly reduced egg hatch.

A generalized competition model for predators or parasites was developed from data obtained from a specific parasite–host system. It was structured in three parts. The first simulates the effects of exploitation, where the number of attacks and their distribution among prey or hosts determine how many prey or hosts survive. Since the negative binomial distribution described these distributions consistently, the exploitation submodel was developed from it. The second portion of the competition model concerned interference between searching predators and parasites. Although interference is a universal phenomenon, we were able to show that its effects become important only at predator densities much higher than those that occur in nature. Thus the interference component can be essentially ignored. The third and final component concerned the outcome of competition between parasite progeny within their host. It was developed from Fujii’s competition model which allows for the simulation of both scramble and contest types of competition.These three submodels of competition were combined and coupled with a previously published model of the effects of prey density on attack. In this way the full consequences of different prey and predator densities could be simulated using a model whose constituent parts had been carefully tested for descriptive adequacy. The simulations showed the way individual predator attack, per cent predation, and progeny production were affected by different degrees of contagion in the distribution of attacks, by scramble vs. contest competition, and by the degree to which parasites could avoid hosts already attacked.

A simple model for growth and development of the ladybird beetle (Hippodamia convergens G-M.) which partitions aphid biomass eaten into components of excretion, assimilation, growth and/or reproduction, and metabolic costs associated with searching and maintenance respiration is reported. All parameters in the model were estimated from simple minimal laboratory experiments, and have biological and/or physical meaning. The effects of predator nutrition on aging, survival, and emigration were also modelled. Most rates in the model for growth, reproduction, and respiration are controlled by the interplay between prey consumption and maximum prey biomass demands. The model for biomass flow is related to standard predator/prey theory.

The sexual behavior of 11 species of Pyrota is described. Analysis of the functional significance of anatomical secondary sexual characters in these species and a survey of similar modifications in others indicates that the general pattern observed is characteristic of the genus. Adults exhibit little aggressive behavior, and courtship involves prolonged physical contact between the sexes. Male courtship activities follow a regular cyclic pattern, as he alternately mounts above the female to perform one series of acts (palpation, dorsal antennation, and rocking) and orients behind her to perform another (leg grasp, palpal insertion beneath her elytra, lifting of her body, posterior antennation, abdominal curvature and stroke, and genital hold). Copulation entails abdominal pumping by the male.

As a prelude to comparative studies, a new classification of the Meloidae is proposed. Characters of sexual and related behavior at the subfamilial level and anatomical characters associated with them are discussed in an evolutionary context. Nemognathinae and, by inference, Eleticinae have simple courtship behavior, copulate dorso-ventrally for short periods of time, and do not prepare sites for oviposition. Meloinae have more elaborate courtship, copulate in a linear position for extended periods, and oviposit in specially prepared cavities in the ground.

Compared with that in other Meloidae, courtship behavior in Pyrota is both complex and highly distinctive. Interspecific differences, considered in detail for six species, involve variation in the precise manner of performance of acts and their temporal relationships. Systematically the ethological data are in reasonable accord with those from other sources except that the courtship behavior of P. concinna is more divergent from that of its presumed relatives than would be expected on the basis of anatomical and ecological characters. An explanation of this discrepancy is proposed in terms of the evolutionary reinforcement of ethological differences functioning in interspecific reproductive isolation.

Hot spots may develop quickly in farm stored grain under Canadian winter conditions. Heavy infestations of mites, insects and fungi may accompany such hot spots (Stirrett and Arnott, 1933; Watters, 1955). Once the heating process is initiated, whatever its cause, it brings about a rapid deterioration of grain, tluough charring of kernels, and reduction of their germinability, and by providing optimum conditions for the growth and reproduction of storage fungi, insects and mites.

The fauna of the sporophores of the perennial bracket fungus Fomes fomentarius (L. ex Fr.) Kickx were examined in a 3-year study. One species of molluscs and more than 152 species of arthropods excluding mites, representing 13 orders, 70 families, and 5400 individuals, emerged from or were found on or in, 1448 sporophores detached from dead birch trees; the sporophores were collected each year in Gatineau Park, Que., kept individually in screen-topped glass jars in a laboratory, and examined for several months. Mites, which were recorded quantitatively only in the final year, added 4 orders, 19 families, and 30 species to the preceding totals. Mites were the most frequently occurring and probably the most numerous arthropods, followed by Coleoptera, Psocoptera, Collembola, Hymenoptera, and Diptera.The key organisms of the fauna were five species of beetles that were primarily responsible for tunnelling and destruction of the sporophores and would therefore exert great influence on the composition of the community. Their tunnels provided shelter and food for many smaller arthropods or facilitated their feeding. Some beetle species tunnelled the sporophores for one season and others, for several, but many living sporophores and most dead ones tunnelled by beetles were tunnelled in the same season by more than one species of beetles.There was considerable latitude in types of sporophores inhabited by various arthropods but some species were particularly attracted to living or dead, to younger or older, and to smaller or larger, sporophores. Some species were also attracted to certain regions of the sporophore more than were other species.Possible economic implications of observations made in the study are discussed.

Baker and Wharton (1952) elevated the Phytoseiidae, formerly a subfamily in the Laelaptidae, to family rank and included two subfamilies: the Phytoseiinae and the Podocininae. Evans (1957) subsequently elevated the latter to family rank also, leaving only the subfamily Phytoseiinae in the Phytoseiidae.

Both Evans (1958) and Chant (in press) characterized the Phytoseiidae as having a two-tined palpal claw, a single dorsal shield in the adult, not more than 21 pairs of setae on the dorsal shield, and a ventrianal shield, or remnant thereof, in the adults of both sexes. One of the present authors (H.A.D.) recently collected specimens of a mite that has this combination of characters except that the dorsal shield of the adults is divided into two sub-equal parts instead of being single. Most of the features of this mite indicate that it cannot reasonably be separated from the Phytoseiidae and that the presence of two dorsal shields justifies the erection of a new subfamily, described below.

The reactions of resistant and susceptible Abies grandis to attacks by Scolytus ventralis are described. Resistant reactions were characterized by the production of secondary resin in the cells of the phloem parenchyma and the formation of callus tissue and traumatic resin cavities at the cambium–sapwood interface. S. ventralis exhibited varying degrees of gallery establishment on resistant hosts. Some individuals were repelled by phloem resinosis before reaching the vascular cambium while others were able to construct galleries of varying length before they were repelled by resin flow from the phloem and traumatic cavities. The degree of gallery establishment appeared to be inversely associated with the rapidity of the host’s response. Necrotic resinous lesions developed around the attack and extended vertically to various distances from the attack. Callus tissue, produced at the margins of this lesion, eventually grew over and healed the wound. Vulnerable grand firs were characterized by the lack of resinosis in the phloem parenchyma, and the absence of extensive callus production and traumatic cavity formation.

A mark–release–recapture study was conducted with dye-marked eastern subterranean termites, Reticulitermes flavipes (Kollar), at two sites in metropolitan Toronto. Interconnected termite galleries were found to extend up to 79 m and to cover areas of 266 and 1091 m2. Colony foraging populations at the two sites were estimated at 2.1 and 3.2 million termites. These foraging distances and population estimates exceed those reported for R. flavipes in other regions.

The spruce beetle, Dendroctonus rufipennis (Kirby), has possible life cycles of 1 or 2 years. Empirical and experimental evidence suggest that temperature is the primary regulator of these life-history pathways. These different life cycles potentially result in substantial differences in population dynamics and subsequent spruce mortality. A multiyear field study was conducted in Utah, Colorado, and Alaska, to monitor spruce beetle development under a variety of field conditions with concurrent air temperature measurements. This information was used to model the tree- or stand-level proportion of univoltine beetles as a function of air temperature. Temperatures were summarized as averages, cumulative time, and accumulated heat units above specified thresholds over various seasonal intervals. Sampled proportions of univoltine insects were regressed against the summarized temperature values in logistic models. The best predictive variable, as evaluated by Akaike’s Information Criterion, was found to be cumulative hours above a threshold of 17 °C elapsed from 40 to 90 days following peak adult funnel-trap captures. Because the model can be used to forecast trends in spruce beetle populations and associated spruce mortality, it is a tool for forest planning.

Exotic ambrosia beetles (Curculionidae: Scolytinae) in the tribe Xyleborini include destructive pests of trees growing in horticultural cropping systems. Three species are especially problematic: Xylosandrus compactus (Eichhoff), Xylosandrus crassiusculus (Motschulsky), and Xylosandrus germanus (Blandford). Due to similarities in their host tree interactions, this mini-review focuses on these three species with the goal of describing their host-selection behaviour, characterising associated semiochemicals, and assessing how these interactions relate to their management. All three of these Xylosandrus spp. attack a broad range of trees and shrubs. Physiologically stressed trees are preferentially attacked by X. crassiusculus and X. germanus, but the influence of stress on host selection by X. compactus is less clear. Ethanol is emitted from weakened trees in response to a variety of stressors, and it represents an important attractant for all three species. Other host-derived compounds tested are inconsistent or inactive. Verbenone inhibits attraction to ethanol, but the effect is inconsistent and does not prevent attacks. Integrating repellents and attractants into a push–pull management strategy has been ineffective for reducing attacks but could be optimised further. Overall, maintaining host vigour and minimising stress-induced ethanol are keys for managing these insects, particularly X. crassiusculus and X. germanus.

The fecundity of first-generation adult Pholetesor ornigis (Weed) increased when individuals were confined with flowers of creeping "Charlie" (Glechoma hederacea L.), dandelion (Taraxacum officinale Weber), and apple (Malus domesticus L.), but not with blossoms of chickweed [Stellaria media (L.) Cyrillo] or Shepherd’s purse [Capsella bursa-pastoris (L.) Medic]. Longevity of P. ornigis was little affected. The fecundity of second-generation P. ornigis increased when individuals were confined with terminal leaves of apple with honeydew of the aphid Aphis pomi DeGeer, but not when confined with terminal leaves without honeydew or with flowers of round-leaved mallow (Malva neglecta Wallr.) or red clover (Trifolium pratense L.). Longevity of P. ornigis adults also increased when they were provided with aphid honeydew. There were significant differences between the total number (oviposited and ovarian) of eggs produced by second-generation females given different food sources. Those given aphid honeydew oviposited a greater proportion of their eggs than those confined with apple leaves without honeydew or with flowers of M. neglecta or T. pratense, Adult P. ornigis fed an aqueous solution of honey (50:50, v/v) lived longest and produced more eggs than those provided with any other food source.

During the 1977–1986 outbreak of mountain pine beetle (Dendroctonus ponderosae) in southwestern Alberta and Saskatchewan, populations of this beetle developed in lodgepole pine and limber pine stands, and threatened to spread northeasterly to the extensive jack pine forests in the central parts of the two provinces. To assess jack pine as a potential new breeding host, I compare egg galleries, brood production, and adult characteristics of D. ponderosae reared in lodgepole, limber, and jack pine logs. Brood productivity, beetle size, sex ratios, and egg gallery characteristics are described for beetle populations reared from naturally infested limber pine logs from southwestern Alberta, and from artificially infested jack pine logs from east-central Alberta and central Saskatchewan. In a field experiment where logs of the three hosts were placed together, adult beetles and their gallery characteristics are described and compared on the three hosts. The results confirm that jack pine is a viable host, that D. ponderosae’s attack characteristics, survival, and progeny on jack pine all appear comparable to those characters observed for beetles reared on lodgepole pine, and that limber pine is highly productive of beetle brood.