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.

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.

Adult ♀.—Length, 5 mm.; width, 3 mm.; many are smaller than this, but this seems to be the average size of the adult containing eggs. Colour yellowish-gray, although they appear light gray, from the mealy secretion which covers the body.

Shape, ellipsoidal, dorsal surface quite convex, ventral surface flat, extremities rather pointed. segmentation quite distinct to naked eye. Extremely short lateral appendages, little projections just visible; caudal appendages a little longer.

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.

After about 20 years of wide usage in integrated pest management (IPM) programs on peach in the Niagara Peninsula of Ontario, populations of Oriental fruit moth, Grapholita molesta (Busck), resistant to azinphosmethyl and phosmet have been selected. Resistance, as expressed in first-instar larvae, was only two- to four-fold to azinphosmethyl or phosmet, but up to 45% fruit infestations have been documented in commercial blocks. Resistance to azinphosmethyl was not well expressed in adult Oriental fruit moths. In tests with larvae, cross-resistance occurred to most other organophosphorus insecticides except acephate and chlorpyrifos. Acephate was more toxic to resistant than to susceptible larvae. Resistance was higher (> 100-fold) to the methyl carbamates carbaryl and carbofuran but was approximately fivefold to the carbamoyl oxime methomyl. Cross-resistance to pyrethroids was not observed. Tests with field-collected material, either from crosses on mating trays in the field or from pupae collected in cardboard bands attached to trees, indicated that resistance was widespread across the Niagara production area but that the resistance was not uniformly expressed at all locations. Resistance was expressed in F1 larvae from crosses of susceptible females with field-collected males, indicating that the genetic change in resistant larvae was unlikely the effect of a single recessive gene. Field tests in replicated two-tree plots and in larger (0.25–0.6 ha) plots treated with up to five applications as a season-long control program indicated that neither chlorpyrifos nor acephate were as effective as a pyrethroid (deltamethrin). The sustainability of these IPM programs and potential resistance management strategies are discussed.

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.

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.

Bumble bees rely on stored nectar to maintain high colony temperatures. This study examines some of the costs associated with exhausting stored nectar for a day in confined colonies of Bombus occidentalis Greene and B. melanopygus Nylander. Workers from energy-deprived colonies ceased incubating and allowed brood temperatures to drop to ambient levels. Workers from energy-rich colonies responded to a simulated vertebrate predator by actively moving about and buzzing loudly (apparently searching for the source of disturbance), but those from energy-depleted colonies mostly remained stationary on the comb. Workers from energy-rich colonies responded to an intruding social parasite (a Psithyrus insularis Smith queen) by chasing and attacking it, whereas those from energy-depleted colonies adopted stationary threat postures. In both cases, the more successful defensive strategy of simultaneous attack by several workers was not employed by nectar-depleted colonies. Cooling of final-instar larvae and pupae added to their development times (disproportionately so in the case of pupae), but low temperature per se did not affect their probability of survival. Hence, the costs of short-term energy shortfall include increased susceptibility to predators and parasites and a lengthened period of development. These costs probably relate to energy stores in a nonlinear manner, providing the foundation upon which risk-sensitive foraging decisions can be based.

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.

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.

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.

Our objective was to assess the potential of carabid beetles (Coleoptera: Carabidae) as effective bioindicators of the effects of forest management at a Canadian national scale. We present a comparison of carabid beetle assemblages reported from large-scale studies across Canada. Based on the initial response following disturbance treatment, we found that carabid assemblages consistently responded to disturbance, but responses of individual species and changes in species composition were nested within the context of regional geography and finer scale differences among forest ecosystems. We also explored the relationship between rare and dominant taxa and species characteristics as they relate to dispersal capacity and use of within-stand habitat features such as coarse woody debris. We found no relationship between life-history characteristics (such as body size, wing morphology, or reported associations with downed wood) and the relative abundance or frequency of occurrence of species. Our results suggest that carabids are better suited to finer scale evaluations of the effects of forest management than to regional or national monitoring programs. We also discuss several knowledge gaps that currently limit the full potential of using carabids as bioindicators.

Supercooling point, biochemical metabolites, and water content of the larvae of Choristoneura fumiferana (Clem.) were measured during pre-diapause and diapause development under laboratory conditions. Supercooling point dropped significantly, from a mean value of −22.9 °C to −31.7 °C during the 3-week pre-diapause development. Supercooling point continued to decline down to −34.5 °C after the beginning of diapause. Water content also dropped significantly during pre-diapause development and was maintained at a low level during diapause. Significant amounts of glycerol were detected only when the larvae were 5 weeks into diapause and the glycerol level continued to increase until week 20 when it was almost 10 times its original level. Glycogen was nearly depleted after diapause, but lipid remained at a relatively high level. Little change in glucose and trehalose content was found during diapause in spite of their initial rise before diapause. Larvae could survive low temperatures close to their supercooling point without freezing but none survived freezing, suggesting that this species is freeze-intolerant. First-instar larvae were found to excrete green material out of their body within 5 days after emergence. Removal of this material from the insect body coincided with a significant drop in supercooling point, indicating that a potential nucleating factor might be involved in the green material. The implications of these results for the overwintering strategy of C. fumiferana are discussed.

Females of the polyphagous ichneumonid parasitoid, Exeristes roborator (F.), that were conditioned for 10 days to hosts in a specific habitat demonstrated associative learning by responding with ovipositor probes into the habitat alone. Females conditioned immediately after eclosion showed a higher participation rate, intensity, and duration (approximately 7 days) of learned behavior than those conditioned 5 or 10 days after eclosion, despite the fact that newly eclosed females did not probe for hosts with their ovipositors until 4 or 5 days after eclosion. The reduction in the learning ability of females within a short time after eclosion may impart a selective advantage to E. roborator by reducing the costs of learning. It could also reflect developmental constraints on the process of learning. The results suggest that carefully controlled associative learning could be exploited to improve the efficiency of host location by parasitoids released in biological-control programs.

Data on the parasitic associations of larval water mites with imaginal aquatic insects are reviewed. Documented associations now are known for larvae of 47 genera of water mites in 23 families representing all seven superfamilies. The particular importance of the nematocerous Diptera, and especially the Chironomidae, as hosts of larval water mites is demonstrated, primarily on the basis of new data. New insights into the evolution of parasitic behaviour patterns in larval water mites are discussed.