The occurrence and abundance of larvae of Chironomus tentans Fabricius in saline lakes in central British Columbia were studied with respect to: (1) physico-chemical properties of the lakes, (2) physical composition of the bottom muds, (3) food availability, and (4) co-occurrence with other species of chironomids. The study was done to determine the ranges of environmental conditions to which the larvae are adapted and to identify specific environmental factors which might be of particular significance to natural selection. Abundance was significantly correlated with the amount of food available; the numbers of individuals of other Chironomus present; the percentage of mud particles in the 0.59–0.83 mm range; pH; conductivity; and the concentrations of potassium, magnesium, chloride, sulfate, and dissolved oxygen. In general, occurrence was affected by the same factors which affect abundance. Additionally, larvae did not occur when hydrogen sulfide was greater than 0.3 p.p.m. The ecological data are particularly relevant since they provide a basis for studying the evolutionary significance of ecological adaptation in C. tentans.

A new classification of dormancy in insects is proposed on the basis of the evolutionary nature of dormancy, its synchronization with the aetiology of the species for their phenological advantage, the nature of ecological adversity, and the consequent physiological and biochemical adjustments. The roles of the above factors in the induction and termination of dormancies are discussed. The inadequacies of all the previous systems of describing various conditions of dormancy are pointed out.All instances of dormancy are divided into three major groups: hibernation, aestivation, and athermopause. Each of these classes is further subdivided into three categories representing a sequence of evolutionary adaptations: quiescence, oligopause, and diapause, in that order of evolutionary development. Depending upon the physiological condition of diapausing individuals or populations, two diapause states are recognized: teleodiapause and ateleodiapause. Each term is defined and discussed with examples.

Between 1961 and 1965, 15 species of predators from India and Pakistan were introduced into North Carolina for use in biological control experiments on the balsam woolly aphid. Recovery studies of these species have been made, but to date there is no evidence that any has become established. Lack of establishment is attributed largely to important differences in climate between the old and new environment and also to poor prey acceptance on the part of predator larvae and ovipositing adults.

Pine root collar weevil damage is least on red pine plantations in cooler areas of northern Lower Michigan, and is inversely related to distance of the host from the nearest weevil infestation. Three hazard zones are suggested based on temperature. A high hazard zone occurs in the western part, a moderate zone in the central, and a low zone in the eastern part of the Lower Peninsula of Michigan.

Two general models are presented to describe the relations between the average number of insects bisected by sampling unit boundaries, the per cent edge-effect bias of mean-brood-density estimates, the shape and size of the average individual, and the shape and size of the sampling unit. The two general models, when expanded specifically for sampling late-stage mountain pine beetle broods, gave excellent fit to experimental data. The expanded equations are approximations since individual insects were considered as being rectangular in shape and the angles of the long axes of their orientation relative to the sampling unit boundary were considered to have a uniform frequency distribution. Edge-effect bias was a function of the size and shape of the organism and those of the sampling unit. Edge-effect bias resulting from faulty sampling-unit-area delineation is also considered, and suggestions are made for its reduction in sample surveys of sub-cortical insects.

The number of molted head capsules of Pissodes nitidus is four, but the frequency distribution of the head-capsule widths and lengths of the weevil larvae do not always show four clear separations. It is necessary for more reliable determination about larval instars to count the molted head capsules in the larval gallery.

A technique for rearing Hyssopus thymus is described by which easy observation of behaviour and development is possible. The life history and observations on paralysis, oviposition, host-feeding, and mating in this species are given. Complete development takes about 17 days at a constant temperature of 24 °C. Because H. thymus is common and widespread, shows no selection for attack at different tree crown levels, and has been responsible for up to 37% parasitism of overwintering Rhyacionia buoliana larvae, it is concluded that it is the most effective native parasite of R. buoliana in Ontario.

Female midges were reared in isolation and allowed to produce unfertilized eggs. Some egg batches of Chironomus atrella, C. attenuatus, and C. stigmaterus showed evidence of parthenogenesis. In C. attenuatus 733 unhatched embryos and 191 hatched larvae were counted among approximately 9771 eggs produced by 12 females. In attempts to rear them, some of the parthenogenetic larvae attained the fourth instar.

A Berlese–Tullgren funnel is described which features a 600-w heating element, a tray having a single bottom of new design, and ventilating screens below the tray to prevent condensation of moisture on the inner wall of the funnel. The funnel efficiently extracts grassland arthropods from coarse plant matter. Also described is a salt-water flotation separator, which extracts any arthropods from the fine litter and soil that may pass through the funnel screens.

A method is proposed for rapidly estimating the population levels of European pine sawfly in young red and Scotch pine plantations. On the hypothesis that the numbers of larval colonies per tree are distributed within a stand according to a negative binomial series, it is shown that an estimate Y of the mean sawfly count per tree in any relevant pine stand may be predicted from knowledge of the proportion p of trees infested, by means of the equation

in which k is an estimate of a distribution parameter. The estimate k is derived beforehand, by Maximum Likelihood from a series of insect populations representative of those in which predictions are contemplated.Approximate 95% confidence limits for estimated densities are computed from a variance estimator reflecting two sources of error. The plotted confidence bands pertaining to samples of various size furnish a simple criterion for judging directly from the proportion of infested trees whether or not suppression measures are needed in a plantation.

Intensive studies on the damage and losses of flue-cured tobacco caused by the dark-sided cutworm, Euxoa messoria (Harris), were carried out in the field at Delhi, Ont., during 1967 and 1968. A new method for estimating the accurate tobacco crop losses is illustrated. Assessment of damage of the tobacco plant and the population density in relation to the yield are described. The yield was significantly related, negatively, to the dark-sided cutworm density, and was reduced in the cutworm-damaged blocks in comparison with the yield in the undamaged check blocks. Assessment of average losses caused by the species was 17% of marketable tobacco, which, based on the average current prices, would amount to 200 dollars per acre or approximately 25 million dollars over the country as a whole every year.

Larvae of Wyeomyia smithii (Coquillett) were collected in Saskatchewan from pitcher-plants in swamps near Nipawin, Little Sandy Lake, and Waskesiu. Pupae and adults also were collected at Nipawin. No trace of W. smithii was found in pitcher-plants in a swamp near Duck Lake. Inconclusive evidence was obtained concerning the presence of W. smithii in a pitcher-plant swamp at Prince Albert.

Species of the genus Trigonotylus Fieber are revised for North America. A new species, mexicanus, is described from Mexico and British Honduras. Synonyms proposed are: californicus Carv. = longipes Slat. & Wagn., and montanus Carv. and viridis (Prov.) = ruficornis (Geoff.). Redescriptions are given for 15 previously described species known from North America: americanus Carv., antennatus Kelt., brooksi Kelt., canadensis Kelt., coelestialium (Kirk.), confusus Reut, dohertyi (Dist.), flavicornis Kelt., longipes Slat. & Wagn., pulcher Reut., ruficornis (Geoff.), saileri Carv., slateri Carv., tarsalis (Reut.), and uhleri (Reut.). A key to species, additional records on distribution, and illustrations of the male genitalia of all the species are given.

The results of systematically conducted field observations revealed that the site of male:female assembly for mating in apple maggot flies, Rhagoletis pomonella (Walsh), was exclusively on the fruit of the larval host plant. Laboratory observations were in strong agreement with this finding.

Laboratory feeding experiments on Celerio euphorbiae (L.) showed that each larva consumed about 2.7 g dry weight of Euphorbia cyparissias L. Laboratory-reared and field-collected larvae produced pupae of similar weights and the close similarity between the fresh and dry weights of control-fed larvae and larvae allowed to feed freely indicates that laboratory results are readily extrapolated to field conditions. On one infested site, at Braeside, Ont., the amount of spurge foliage was measured and the density of larvae needed to graze it fully was estimated at 14/m2 completing development. Preliminary data on an energy budget of the larva are discussed in relation to possible damage to the plant.

A new genus, Archepiolus, and a new species, schmidi, belonging to the family Neopseustidae and suborder Dacnonypha are described in this paper. This genus and species occupy a very primitive position in the Neopseustidae. The venation shows the most primitive features in all the Dacnonypha; also the male genitalia show a more primitive condition than that of Neopseustis meyricki Hering. Some aspects of the male genitalia are close to Mnesarchaea paracorma Meyrick of the Mnesarchaeidae.The discovery of this moth provides new morphological evidence on the problem of the ancestors of the Dacnonypha and of all Lepidoptera.

The results of behavioural, chemical, and histological studies are reported showing the presence of a sex attractant in female Orgyia leucostigma J. E. Smith. A method of bioassaying the attractancy of the female moths by the use of 4-ft-long glass tubes is given. Extraction of female abdominal tips with dichloromethane yields material biologically active when tested against male O. leucostigma.The pheromone-producing gland is a dorsally situated, crescent-shaped structure formed by modification of the epidermal cells in the intersegmental membrane between the eighth and ninth abdominal segments. The glandular cells are goblet-shaped and are arranged in an unusual manner.

The balsam woolly aphid, Adelges piceae (Ratz.), in Newfoundland is dimorphic and has three generations a year in the crowns of balsam fir trees. Two generations of the sistens, or diapausing form, predominate. Progredientes are more common than elsewhere in North America and occur on nearly all parts of a branch. They do not mature on current needles. The ratio of progredientes to sistentes is about 1:40 in balsam fir flowering years and 1:80 in non-flowering years. Aphid development in the spring is earliest at flowered internodes, 11 to 14 days later at 2-year-old nodes, a further 4 to 8 days later at older nodes, and latest at the shoot tips. Intra-crown and inter-tree differences in aphid development are small but measurable. Stratification of the tree crown is required for sampling during the first aphid generation.

Range extensions and habitat data are given for two species of Chironominae: Chironomus (Chironomus) atrella (Townes) and Chironomus (Einfeldia) paganus (Meigen) from Saskatchewan. The first is a new record for Saskatchewan; the second is new for Canada.

Sexupara production in the pear root aphid, Eriosoma pyricola Baker & Davidson, was closely associated with the cessation of shoot growth of its host in the field in irrigated and non-irrigated plots in two successive, but phenologically different years. Neither the environment nor the host plant were unfavorable at the time the sexuparae were formed, indicating that the aphid uses the host plant as a source of seasonal information.

The nature of synchronization between active development of univoltine insects and trees is discussed. It is concluded that the initiation of dormancy in trees and diapause in insects is not likely to be synchronized by a common set of environmental factors. Either regulation of insect diapause by host trees is more common than is currently recognized, or environmental and age differences in tree growth have favored selection for obligate diapause.