A technique is described for rearing successive generations of the insect in numbers from 200 to 40,000 continuously without diapause. All components of the diet are commercially available and the principal ingredients are of plant origin. Survival at four stages of development is given and the causes of mortality are discussed. The per cent survival of insects from instar III to pupation times the percentage of perfect female pupae obtained at harvest gives a factor considered to be the best measure of the worth of an artificial diet. The variability of these statistics is shown by frequency distributions obtained in 50 independent tests of the diet. Overall survival of 84% times 73% perfect females gave a diet worth factor of 61. An analysis of rearing costs is presented. Although 15 continuous generations have been reared, egg production of the highly selected strain has not deteriorated.

In this overview we compare the significance and evolutionary history of two interacting biological systems, the conifer-feeding bark beetles (Coleoptera: Scolytidae) and their host conifers (Gymnospermae: Coniferales and Taxales). Isoprenoid natural products play key roles in the aggregation of the bark beetles and in the defence of the conifers. Our approach is to couple the most recent advances in the biochemical and molecular literature on these systems with ecological and behavioral data to compare monoterpenoid pheromone biosynthesis in scolytids with monoterpene biosynthesis in conifers. This synthesis reveals and evaluates the evolutionary redundancy occurring in the biochemical systems of the insect and host. Although host monoterpenes may be utilized directly or as derivatives in aggregation by scolytids, oxygenated monoterpenes that are behaviorally active for scolytids have been rarely identified from their coniferous hosts. De novo monoterpenoid biosynthesis in the Scolytidae, a process that is likely to be rare among metazoans, is substantially different from monoterpene biosynthesis in the conifers. The pathways appear to be shared only at the late-stage reactions that follow the formation of isopentenyl diphosphate. Little is known of the regulation of monoterpene biosynthesis in conifers, but scolytids positively regulate monoterpenoid biosynthesis using a sesquiterpenoid hormone, juvenile hormone, which does not occur in conifers. Little is known of the subcellular site of synthesis of monoterpenoids in scolytids, but conifer monoterpene biosynthesis is compartmentalized in the plastids, which do not occur in scolytid cells. In addition to bark beetles and conifers, the vertebrate model presents one of the few systems in which isoprenoid synthesis has been studied enough to provide a meaningful comparison. Possible unique features of monoterpenoid pheromone biosynthesis in scolytids relative to isoprenoid biosynthesis in vertebrates include the following: (1) a monoterpenoid end product; (2) a hypothetically scolytid-specific prenyl transferase (= geranyl diphosphate synthase) that catalyzes the condensation of two five-carbon (C5) units, but does not catalyze additional condensation reactions with the C5 monomelic unit; (3) a scolytid-specific monoterpene (myrcene) synthase; and (4) a scolytid-specific, transcriptional-level sesquiterpenoid isoprenoid regulatory mechanism. Features 2 and 3 may be shared with conifers. This review also updates the 1985 landmark scientific paper by John Borden by listing the references and species of coniferophagous Scolytidae for which aggregation pheromones have been identified since 1985.

Carabid beetles were collected with grids of pitfall traps during two seasons in five habitats in the ecotone between aspen parkland and boreal mixedwood forest in central Alberta. The 23 abundant species (54 species in total) were divided into the following four distributional types: (1) Pterostichus adstrictus Eschz. was numerous in all five habitats (habitat generalist); (2) Platynus decentis Say, Calathus ingratus Dej., and Scaphinotus marginatus Fisch. were abundant in all four forest habitats (forest generalists); (3) another 10 species were common in one or two forest habitats (forest specialists); (4) nine species, representing mainly Agonum, Amara, and Bembidion, were restricted to a recently cleared timothy–clover grassland (meadow species). Soil moisture seemed to be important in determining habitat associations of the species among the forest types. Captures of most species were aggregated also within habitats, and the consistency of aggregation among particular traps suggests that it is mainly a response to subtle microhabitat differences. All abundant species, except S. marginatus, showed a peak of capture in May–June. Number of species, corrected for sample size by rarefaction, was highest in the meadow (27.5) and lowest in the dry upland aspen forest (11.9). Species diversity was highest in meadow and the lakeside forest habitats, but carabid assemblages of the four forest habitats were more similar to each other than to the meadow assemblage.

I review reports on the genetic basis for species differences in the Lepidoptera. In the six best-studied species complexes, more than half of all ecological, behavioral, or physiological differences among species are controlled by X-linked genes. Because Lepidoptera have about 30 pairs of chromosomes, this finding clearly indicates strong bias toward X-linkage of genes for species differences. The proportion of X-linked species differences ranges from complete X-linkage in Colias butterflies, to almost none in Yponomeuta moths. Four other complexes all have at least one X-linked gene that is crucial to species differences, including the Choristoneura fumiferana Clemens, Papilio glaucus L., and Papilio machaon L. species groups, and Ostrinia nubilalis Hübner pheromone strains. The mechanisms that account for this phenomenon are open to speculation. Nonetheless, an interesting implication of disproportionate X-linkage is that reproductive isolation may frequently arise by selection on linkage complexes, rather than as a random byproduct of evolution in geographically isolated populations. If confirmed, the bias toward X-linked species differences may also help efforts to find characters that distinguish host races and sibling species, as well as provide an avenue by which genes crucial to speciation can be more easily mapped and characterized at the molecular level.

Several species of wireworms were attracted to germinating wheat, air from flasks of germinating wheat, decomposing oatmeal, commercial CO2 and, in addition, germinating seeds of eight other cultivated plant species. Larvae located a biological or experimental source of CO2 by a directed movement along CO2 gradients, from distances up to 20 cm.

Methods and apparatus for measuring small CO2 gradients, using gas chromatography and mass spectrometry, are described. Ctenicera destructor (Brown) larvae apparently responded to CO2 gradients between glass plates, that ascended on the average by 0.002% (soil) and 0.005% (agar)/cm over a distance of from 12 to 16 cm. The "sensitivity threshold" was calculated as being 1–2 ppm over the distance involved in one deflection of the head during klinotactic orientation. Attractancy was observed within a range of CO2 concentration from about 0.036% to 1.5%. Repellent effects did not appear to be only related to concentration, but possibly were due to steepness of the gradient and(or) previous exposure to CO2.

Passing an air stream from germinating grain over a KOH solution eliminated the attractancy of the grain by removing the CO2 and possibly other undetected attractants. A small percentage of C. destructor larvae apparently oriented to an ethylene source, but it was concluded the CO2 was the most important if not the only attractant from germinating wheat seeds.

In field investigations on the relative resistance of varieties of peas, Pisum sativum L., to the pea aphid, Acyrthosiphon pisum (Harr.), the average number of aphids per terminal growth for 13 years (Maltais, 1937, 1950, 1951, and unpublished technical report, 1950-54) for six varieties was as follows: Perfection, 39.6; Daisy, 32.6; Lincoln, 35.6; Laurier (H-103), 9.8; Champion of England, 11.8; and Melting Sugar, 16.8. In a preliminary investigation by Auclair and Maltais (1950), 11 free amino acids were detected in pea plant extracts by paper chromatography. From a visual comparison of chromatograms, the variety Perfection appeared to contain a higher concentration of most free amino acids than the variety Laurier. This is a report on the quantitative estimation of the free and total amino acid contents of the three susceptible varieties (Perfection, Daisy, and Lincoln) and the three resistant varieties (Laurier, Champion of England, and Melting Sugar) by the method of paper chromatography.

Dilemmas in weed biocontrol are wide ranging. Even the term biological control is confusing as meanings may be restricted to the use of parasites and predators or extend to the use of all non-chemical means of control. Another problem is that two-thirds of the agents released do not become numerous enough to inflict major damage to the weed population, although this statistic is misleading as it includes agents costing little in pre-release studies where failure is of little consequence and those costing about two scientist years each, or currently about $400,000. Many of the suggestions for improvement are costly and time consuming. Delay is unacceptable where agent release is seen by sponsors as a mark of progress in a program likely to require 20 years and funding is difficult. Analysis of previous biocontrol attempts for attributes of "success" have been disappointing, partly because there are a number of steps involved, each with its own attributes. This paper recognizes four graded "success" steps and discusses many agent selection methods.

There are public demands for a change in emphasis from chemical to biological control; but in the absence of effective enabling legislation, the practice of biocontrol can be legally and politically hazardous; biocontrol should be carried out by a multidisciplinary team but it is usually assigned to a single scientist; it needs to branch in new directions to remain scientifically stimulating, but this increases the risk of failure. Possible solutions for these dilemmas are discussed.

New observations on parental behavior of the earwig, Forficula auricularia L., are reported and the literature on the parental behavior in the Dermaptera is summarized. The construction of the nest, care of the eggs and nymphs, and the duration of parental care are described. The control of parental behavior and the role of the male in nest establishment are also considered.

Several insect species have life cycles that last more than 1 year, because of very slow growth, repeated or prolonged dormancies, or very long lived adults. These long life cycles are correlated with environmental adversities, such as cold or unpredictable temperatures, patchy, unreliable or low quality food supplies, and natural enemies, as well as with some other properties such as large size. Long life cycles are most prevalent when several of these factors are present simultaneously. Adversities tend to prolong the life cycle of all individuals in the population, whereas unpredictability tends to extend the life cycle of only some individuals. Extreme extensions, such as diapause for more than 10 years, usually affect only a very small fraction of the population. Modest extensions, such as development over 2 years, prolonged dormancy for one additional adverse season, cohort-splitting between 1- and 2-year life cycles, and oviposition over two seasons, are relatively common. Insects with long life cycles provide insights into the nature of adaptations to adverse and unpredictable conditions, and also provide useful material for the analysis of questions related to population and community structure.

One of the most essential procedures in the identification of many Lepidoptera is an examination of the genitalia, and for a most critical examination of these organs slide mounts must be prepared. In many cases, the preparation of slides is one of the most neglected arts in lepidopterology. This is to be deplored, for a well-prepared slide is not only handsome but also much more valuable taxonomically than a messily prepared one. For large and medium-sized specimens, I have found the following technique very gratifying in producing slides of uniformly high quality. Certain phases of the technique are not particularly well adapted for working with smaller moths.

Surveys in unsprayed orchards showed that the wild flowers that are food sources for adult parasites influence the extent to which host Lepidoptera are parasitized. Proportionately about 18 times as many tent caterpillar pupae were parasitized in orchards with rich undergrowths of wild flowers as in orchards with poor floral undergrowths. The corresponding figures for tent caterpillar egg parasitisms were about 4 to 1, and for codling moth larvae about 5 to 1. Orchards with average undergrowths of wild flowers produced intermediate figures.

Many attempts to establish introduced parasites in Canada failed though the climatic conditions at their release points were apparently similar to those of their native habitats (Thorpe, 1930; Baird et al., 1947). It is known that many adults of hymenopterous parasites feed on flowers, aphid honeydew, host body fluids, and other substances (Jackson, 19 37; Thorpe and Caudle: 1938; Schneider, 1939; Györfi, 1945, 1951; Zoebelein, 1956). This brings up the possibility that nourishment from one or more of the above sources is necessary for surviial and reproduction, and that some of the failures may have been because of the absence or scarcity of suitable adult food (Clausen. 1956). At present data on the food preferences of adult hymenopterous parasites are scarce. Except for a few field and laboratory observations, there are no experiments that demonstrate distinct preferences for one food over another. The results of the experiments described in the present paper demonstrate that adults of the species studied have preferences for some flowers and food substances tested.

An appraisal of population processes in the Colorado potato beetle, Leptinotarsa decemlineata (Say), on its principal host plant showed that the insect has no natural agents that act in a manner that prevent it from overshooting its food supply. It is little affected by weather conditions or predators, and its only parasite, the tachinid Doryphorophaga doryphorae (Riley), is inversely density dependent in its action. Once the beetle has exploited its food resource, the larvae starve and the adults emigrate in quest of other hosts.The analysis of age interval survivals showed that populations are both regulated and disturbed by the principal key factor, adult migration, which is density dependent but overcompensating. A predictive model based on density relationships explained 94% of the variance in population trend.

This is an analysis of the attempts to colonize at least 208 species of parasites and predators on about 75 species of pest insects in the field in Canada. There was colonization by about 10% of the species that were introduced in totals of under 5,000 individuals, 40% of those introduced in totals of between 5,000 and 31,200, and 78% of those introduced in totals of over 31,200. Indications exist that initial colonizations may be favoured by large releases and by selection of release sites that are semi-isolated and not ecologically complex but that colonizations are hindered when the target species differs taxonomically from the species from which introduced agents originated and when the release site lacks factors needed for introduced agents to survive or when it is subject to potentially-avoidable physical disruptions. There was no evidence that the probability of colonization was increased when the numbers of individuals released were increased by laboratory propagation. About 10% of the attempts were successful from the economic viewpoint. Successes may be overestimated if the influence of causes of coincidental, actual, or supposed changes in pest abundance are overlooked. Most of the successes were by two or more kinds of agents of which at least one attacked species additional to the target pests. Unplanned consequences of colonization have not been sufficiently harmful to warrant precautions to the extent advocated by Turnbull and Chant but are sufficiently potentially dangerous to warrant the restriction of all colonization attempts to biological control experts. It is concluded that most failures were caused by inadequate procedures, rather than by any weaknesses inherent in the method, that those inadequacies can be avoided in the future, and therefore that biological control of pest insects has much unrealized potential for use in Canada.

Species in the family Aphidiidae (Hymenoptera) parasitize exclusively ovoviviparous aphids. Females use a variety of information to detect and evaluate suitable hosts. Olfactory cues associated with aphids, or the aphids’ host plant, are important for host location. Visual cues including aphid colour, shape, and movement can be evaluated from a distance without physical contact; aphid movement may act as a releasing stimulus for attack. Contact chemosensory cues (gustatory cues) are evaluated by antennation of the host cuticle and during ovipositor probing. A potential host must conform to the wasp’s response profile and satisfy minimum physiological and dietary requirements for immature development and growth. Host quality is determined in part by attributes specific to each aphid species and in part by each aphid’s individual-specific growth potential. Host quality for male and female progeny may vary as a result of different patterns of resource allocation and sexual size dimorphism. For an encountered aphid to be accepted as a host, its perceived value must exceed the wasp’s response threshold for oviposition. Host value, as opposed to host quality, varies dynamically with parasitoid state variables such as age, egg load, and prior experience. A conceptual model of host choice by aphidiid wasps is presented.

The predators of phytophagous mites are being studied at Vineland Station as part of an investigation of the causes underlying the increase of these mites that foIlows the use of DDT and some orher pesticides in peach orchards (Putman and Herne, 1959). Phytoseiid mites, especially Typhlodromus (T.) caudiglans Schuster, are among the commoner predators.

The relationship of pheromone trap catch to emergence and oviposition of the codling moth was defined for the two-generation climate of Michigan. Catch anticipated emergence and oviposition during spring flight when the trap displayed greatest efficiency, but lagged behind emergence and closely followed oviposition during the second generation. Trapping efficiency declined towards the end of the first generation and was generally lower during summer flight. Factors which possibly relate to this efficiency loss are discussed. First catch and the catch peaks in both generations were evaluated as reference points for the prediction of phenological events (particularly egg hatch) in both generations Of four forecasting methods, degree day and developmental unit summations, starting from first catch, for the preoviposition and incubation period were most reliable in predicting the beginning of spring brood egg hatch.

The diamondback moth, Plutella maculipennis (Curt.), is one of three species of Lepidoptera that annually cause serious commercial damage to cabbage and related crops in Ontario. It has long been underrated as a pest of cruciferous crops, possibly because of its small size; in eastern Ontario, it is much more numerous than the other two species and ranks second in importance to the imported cabbageworm, Pieris rapae (L.) (Harcourt et al., 1955). Its biology in eastern Ontario was investigated from 1951 to 1956. The history, distribution, and synonomy of the insect and general descriptions of the stages were given earlier (Harcourt, 1956). This article presents the life-history, behaviour, and host relationships.

The higher classification of the families of the Noctuoidea with a quadrifid forewing (Nolidae, Strepsimanidae, Arctiidae, Lymantriidae, Erebidae, and Noctuidae) is reviewed from the perspective of recent classifications and the distribution of derived character states. On the basis of recent morphological and molecular studies, we propose a more inclusive definition of the family Noctuidae that adds the subfamilies Nolinae, Strepsimaninae, Arctiinae, Lymantriinae, and Erebinae to the subfamilies more traditionally included in the Noctuidae. Consequently, the superfamily Noctuoidea comprises the families Oenosandridae, Doidae, Notodontidae, Micronoctuidae, and Noctuidae. The tribe Cosmiini, currently in the subfamily Xyleninae, is downgraded to the status of subtribe Cosmiina and placed in the tribe Xylenini. The tribe Balsini, currently in the subfamily Xyleninae, is elevated to the status of subfamily Balsinae. The tribe Phosphilini is transferred from the subfamily Psaphidinae to the Xyleninae.

Inactive moths of Malacosoma pluviale (Dyar) oviposit near their birthplaces, and most of their offspring also are inactive. More active moths can travel farther before they oviposit, and always have a higher proportion of vigorous individuals among their progeny.

Such polymorphism allows the insect to cope with environmental diversity; e.g., inactive residents exploit favourable habitats, and active migrants colonize more severe habitats, or replenish the vigour of other populations.

Because the most active moths usually export the most vigorous progeny, the population left behind becomes less vigorous during successive generations. This steadily decreasing vitality eliminates local populations that are not replenished by vigorous immigrants.

Qualitative changes in Malacosoma populations follow this basic pattern, but the rate of deterioration is affected by the habitat. Departing migrants fly too high to be stopped by small trees in farmland, bur many are stopped near their source by tall trees in forests. Deterioration therefore is slower in forests. Forests also delay return migration to nearby farmlands, and thus allow some farmland populations to deteriorate unchecked.

In a fluctuating climate, the size of the area tolerable for the species varies annually. When it begins to expand, the vigorous progeny of active moths can take immediate advantage of slight local improvements. Consequently, they are the first to exploit each marginal habitat that becomes tolerable. But while better climate persists, some less active descendants of these pioneers appear in all occupied habitats.

When the regional climate deteriorates, the tolerable area contracts, and most marginal populations are totally destroyed. Moreover, even within the contracted tolerable area, the harsher climate becomes intolerable for any deteriorated stock. In the next generation, therefore, the only regional survivors are vigorous colonies deposited in the tolerable area by some of the few migrants that escaped the widespread destruction of the preceding generation in the margins. Their descendants recolonize depopulated sections of the refuge, and so preserve the species in the region while the climate remains severe.