Larvae of Coquillettidia pertubans (Walker) are found in some marshes of permanent water with stands of aquatic vegetation. Eighty-six marshes, located within a 400-km2 area of Hennepin County, Minnesota, were examined in the fall of 1984 to determine factors that characterize C. perturbans breeding sites. We found that C. perturbans larvae attached to the roots of primarily Typha species although other plant species were also used. The water in sites with larvae was significantly deeper, lower in dissolved oxygen, and contained a significantly thicker layer of organic debris than sites without larvae. Larvae were associated with sites where Typha had specialized structures called water roots, which grow in the water column. Larvae inhabiting floating mats of vegetation were associated with interior openings within the mats.

The most suitable temperature for larval development of Aedes vexans Meigen was found to be 25 °C. At this temperature 86% of the larvae survived and pupated in 7 days. At 10°, 15°, 20°, and 30 °C larval development time was 46, 22, 10, and 8 days and survival rates were 17, 56, 74, and 71%, respectively. At 5 °C mortality was 100% in the first-instar stage, the last larva dying 12 days after hatching. Adults emerged in 2 to 5 days after being transferred into water at 25 °C, males emerging 2 days before the females.

Paired mandibular mycangia are present in both sexes of the bark beetle Dryocoetes confusus Sw. These fungus repositories were not found in either sex of another bark beetle of the same genus, Dryocoetes affaber Mann.

An adult of either Coleomegilla maculata lengi or C. m. medialis ate about 280 mg dry Acyrthosiphon pisum in its lifetime at various constant temperatures. Total food consumption and rate of intake increased with temperature and rate did not vary with age. The average ages attained by field-collected and laboratory-reared adults were greatest at temperatures of 17° and 23 °C, respectively, for C. m. lengi and at 23 °C for C. m. medialis. Neither subspecies laid any eggs at 17 °C, C. m. lengi laid some eggs at 23 °C, and both subspecies laid the largest number of eggs at 25 °C. Fertility as percentage of eggs hatched was lower in both subspecies at 34 °C (30%) than at 23° and 25 °C (100%). Ethanol extracts of teak, cinnamon, clove, guaiacol, and resorcinol were the most effective ovipositional stimulants for C. m. lengi when formulated in water. Exposure to the ethanol extracts of different plants increased the incidence of oviposition by 19% and the number of eggs/♀/day by 36% in C. m. lengi.

Following a 3-year period of high populations of the little spruce sawfly, Pristiphora abietina Christ, a monophagous species infesting Norway spruce, Picea abies Karst., we compared variations in foliar nutrients (nitrogen, water, soluble carbohydrates, starch) and potential defensive compounds (fiber, quinic and shikimic acids, tannins) of trees that had been subjected to high or very low levels of defoliation. During the time of needle expansion a substantial decline in leaf quality occurred: nitrogen, water, and carbohydrate levels decreased, whereas fiber and starch concentrations increased. Allelochemicals such as tannins and organic acids, however, peaked at bud break and then rapidly declined. More heavily attacked trees had higher nitrogen, water, and fiber contents but lower starch and organic acid concentrations than lightly attacked trees. The needle tannin content was significantly lower in heavily attacked trees throughout the period of larval feeding. Needle tannin levels and the nitrogen to tannin ratios seem to be the most probable traits to distinguish sawfly-resistant from sawfly-susceptible Norway spruce trees.

Subsocial behaviour, defined as postovipositional parental behaviour that promotes the survival, growth, and development of offspring, has been reported in diverse orders in insects (Tallamy and Wood 1986). Especially in the order Coleoptera, more that 10 families include subsocial species (Hinton 1981; Brandmayr 1992). For chrysomelid beetles, with the exception of members belonging to the subfamily Cassidinae, such behaviour has been known previously in a few species (Windsor and Choe 1994).

The Colorado potato beetle, Leptinotarsa decemlineata (Say), is distributed throughout the world and is an occasional pest of potatoes in Atlantic Canada. During the course of rearing Colorado potato beetles for behavioral studies at the Fredericton Research Station I obtained a strain of beetles which differs from the normal brown morph in being predominantly white. Similar coloring occurs in larvae and pupae and in young female and male adults. The eggs are light yellow instead of the usual orange-yellow. Such an albinic mutant has been previously reported in the United States by Tower (1906) and named L. pallida. Tower found the white mutant to be true-breeding and widely distributed, occurring both in nature and in laboratory colonies. Such a mutant has not been reported since and this is the first record of a white morph in Canada.

Emergence from hibernacula of 2nd instars of Choristoneura occidentalis was more variable but later than that of C. retiniana. However, early-instar development was faster in C. occidentalis and compensated for the difference in emergence times so that both species entered the 6th instar simultaneously. There were no species-related differences in development beyond the 6th instar. Though they have different resource-tracking patterns early in their life cycle, temporal isolation between these species is unlikely. No developmental morphs were found in either species but there were several instances where individuals that developed at an increased (or decreased) rate in one stage developed slower (or faster) than the mean rate in a substantial stage. Negative correlations between development times were indicative of this. These correlations reduced variation in adult eclosion times induced by extended spring emergence and are indicative of homeostasis in development within populations. Negative correlation coefficients between development periods were more common in C. occidentalis, which also had the more variable spring-emergence pattern. Hybrids were intermediate in almost all development traits.

This paper contains a description of a species of Leucopis Meigen, subgenus Leucopella Allalloch (1927), and a note on occurrence of the subgenus in the New World (previouslv known only from Africa). Also a key is given to all the known genera and subgenera of the Chamaemyiidae.

Nymphs of the clear-winged grasshopper, Camnula pellucida (Scudd.) have been observed to evacuate local habitats by marching (11). Except for a few stragglers, apparently all occupantsof the habitat moved in the same direction. Rarely, if ever, did these marches continue for more than 300 yardsin one direction, nor did the insects show much tendency to maintain identity as a band; nevertheless, the capacity of this species to march was clearly shown. The marches always occurred during the day and when the temperature was above 20°C. (8). In all recorded cases the nymphs moved into a cooler and more humid area. The authorhas not observed, or received reports of, instances of marching in the comparatively sluggish two-striped grasshopper, Melanoplus bivittatus (Say).

Three new species, two in the genus Amblyseius Berlese and one in the genus Typhlodromus Scheuten, collected in Canada are described. Three additional Amblyseius species and one Typhlodromus species are recorded for the first time in Canada. The previously unknown males of 9 species are described. These new records bring the total numbers of species in the genera Amblyseius and Typhlodromus in Canada to 53 and 22 respectively.

Estimates of the numbers of the western pine beetle, Dendroctonus brevicomis LeConte, in Pinus ponderosa Laws, bark samples were made by radiographs of 25 bark samples and by dissection counts of the bark. High correlations (r = >.9) between the two methods were found for (a) live larvae, (b) live plus dead larvae, (c) live of all stages combined, and (d) live plus dead of all stages combined. The bark dissection method took eight times as long and was 4⅓ times as expensive as the radiographic interpretation method of estimating bark beetle numbers.

The present carabid beetle fauna (sensu Lindroth 1955, including Carabidae and Cicindellidae) of Newfoundland is compared with that observed by C. H. Lindroth 30 years ago. Five additional species are now known bringing the faunal total to 171 species. Two of these additional species, Chlaenius alternates and Lebia moesta are Nearctic while Carabus granulatus, Leistus ferrugineus, and Bembidion properans are of Palaearctic origin. The known ranges of an additional seven introduced species have increased. The patterns of these range changes support two models of Palaearctic species establishment in Newfoundland: by direct human-assisted introduction onto the island; and through flight across the Cabot Strait by winged species initially established on the North American mainland.

The following is a description of a new species of predacious mite of the subfamily Phytoseiinae. It is found in orchards in Nova Scotia on the bark of apple trees, but in no instance has it been taken from the foliage. This species is similar in structure to Typhlodromus tiliae Oudmus. (Nesbitt, 1951), but its habits differ. In this paper the differences between T. tiliae and the species herein described are noted and details of a laboratory study of the life-histories and food habits of these species are given.

When a host-regulative ectoparasite and a host-regulative endoparasite compete for the same host population (multiple parasitism) the former largely replaces the latter when the host’s density is high, the ectoparasite then being relatively numerous and the endoparasite scarce. However, after the ectoparasite has reduced the host population to a low density the converse is true, the endoparasite being more numerous. This difference is an effect of the endoparasite being able to operate at lower host densities; an essential adaptation if it is to survive competition with a host-regulative ectoparasitic population. The above conclusions are based (1) on the statistical analyses of numerous population samples of ectoparasitic and endoparasitic species of the family Aphelinidae (Chalcidoidea: Hymenoptera) imported into California while inhabiting host coccids (Diaspididae: Homoptera); (2) on field observations by the writer and the reports of others on the numerical status of such hosts and their specific parasites in gardens and orchards in various countries, those in which the species are indigenous as well as in those where they are exotic; (3) on the principles of multiple parasitism as elucidated by Harry S. Smith; and (4) on multiple parasitism by an ectoparasite and a host-specific endoparasite being characterized by the ectoparasite always destroying the endoparasite when both are attacking the same host individual and the endoparasite replacing the ectoparasite when populations of both are subsisting on a low density host population.

The oribatid mite genus Zachvatkinibates, found in littoral, forest canopy, and forest litter habitats, includes some species showing distinct sexual dimorphism in the octotaxic system of dermal glands, and others lacking this dimorphism. Three new species in this genus are described on the basis of adults, each of which shows species-specific sexual dimorphism: Z. nortonisp. nov. and Z. schatzisp. nov. from beach debris in British Columbia, Canada, and Z. shaldybinaesp. nov. from the littoral in eastern and northeastern Canada. We discuss the association of sexual dimorphism with the littoral habitat of species in this genus and, more generally, the expression of sexually dimorphic porose areas in Ceratozetoidea. We revise the diagnosis for the genus Zachvatkinibates and present a revised key for adults of Zachvatkinibates species of North America north of Mexico.

First- and second-instar tent caterpillar larvae are acceptable prey for many native species of ants. The amount of predation which occurs is normally related to ambient temperature. A warm period in early spring allows ants to forage actively and often leads to destruction of the caterpillar colonies whereas a cool spring curtails ant activity and allows the caterpillars to develop beyond the vulnerable period free from predation by ants. In latter instars the caterpillars are protected completely against ants by their dense setae.

The insect fauna of the Canadian prairies is composed of elements recruited from surrounding biomes. Most species appear to have invaded from the southeastern United States following the retreat of the last glaciation. Other distinct centers of origin are the eastern boreal forest, the Rocky Mountains, the Alaskan-Beringian refugium, and the Sonoran or interior basin of the southwestern United States. Because of the youthfulness and instability of the prairies as a biome, true prairie endemic species are rare. While an inventory of prairie insects is far from complete, enough information is available to detect basic patterns of immigration.

Oviposition site selection by Tenebrio molitor L. was studied in cylindrical cages 10 cm in diameter × 28 cm in height using females up to 16 days old. Oviposition site selection is not a haphazard process. The adults are surface dwellers and the females normally enter the foodstuff to oviposit. The distance travelled into the foodstuff was age-related; the females went gradually deeper until the 9th day after eclosion. Physical and chemical factors (i.e. type and quality of foodstuff) and biological factors (i.e. adult density and presence of T. molitor eggs and larvae) were assessed when oviposition sites were selected by this insect. The females attempted to avoid poor quality food when selecting oviposition sites and usually laid fewer eggs and died sooner when poor quality food was present. As adult density increased, the females went deeper to oviposit. The females also went deeper to oviposit when eggs and larvae were present, but the effects of eggs and larvae were small and there seemed to be threshold densities as far as both factors were concerned. The behavioural significance of the data is discussed.

Several species of Lygus (Hahn) that occur in Saskatchewan are serious and continuing pests of alfalfa grown for seed. They are readily controlled by any one of several insecticides, but the efficiency of this control is dependent upon knowing their seasonal development and occurrence on the crop.

In the years 1976 and 1978, at three locations in Saskatchewan, populations of Lygus in alfalfa seed crops were sampled at 5- to 7-day intervals throughout the period of insect activity. In 1979 and 1980 samples of bugs were taken occasionally from the same locations, and in all years from other locations in the province. A sample consisted of 0–700 specimens collected by either a 38-cm sweepnet in not less than 25 and as many as 200 random sweeps, or a D-Vac sampler in not less than 3 m2 in spring and after harvest when sweep-sampling was not possible. Collected specimens were preserved in alcohol, sorted, and identified. Additional data, not previously published, were available from a similar mid-1950's study of Lygus seasonal occurrence in alfalfa seed crops in the Torch River district of northeastern Saskatchewan.