The genera Leptohyphes Eaton and Tricorythodes Ulmer are confined to the New World, and the Nearctic limits of Leptohyphes has been extended from Texas to Maryland and Utah. Useful nymphal characters are presented for both genera, and descriptions and figures are included for 22 new species of Leptohyphes Eaton, and 7 new species of Tricorythodes Ulmer.

A study currently under way required non-attractant traps to collect and preserve for taxonomic identification flying insects inhabiting the crown and shrub layers of a slash pine (Pinus elliottii var. elliottii Engelm.) and pondcypress (Taxodium distichum var. nutans (Ait.) Sweet) forest. We concluded that an omnidirectional flight trap was appropriate. After failing to find a satisfactory design in the literature, we developed the trap illustrated in Fig. 1. Our design combines an original upper collecting unit with a modification of the trap described by Hines and Heikkenen (1977).

The program of biological studies and experiments in chemical control of mosquitoes at Churchill, Manitoba, in 1947 and 1948 (Twinn et al., 1948; Twinn, 1950) was extended in 1949 to include Goose Bay, Lahrador. The program at Goose Bay was primarily designed to develop control measures for the northern species of biting flies. since the control experiments were scheduled for definite periods during the summer in 1949 (Twinn et al., 1950), limited biological studies were carried on as circumstances permitted. These field studies produced information on the species of mosquitoes present and their development and ecology. Data obtained in 1949 from field observations, collections, identifications of adult and immature forms. and limited laboratory rearings are summarized in this paper. Additional data obtained by officers of the Division of Entomology in 1950 under similar circumstances have been included, in some cases as confirmation of observations in 1949.

In Eastern Canada, aphids cause serious losses in the potato crop–directly by injuring heavily infested plants and indirectly as vectors of viruses. A field study of factors affecting populations of potato aphids necessitates a method of estimating population that allows comparisons of results from different varieties of potato and from potatoes grown under different conditions. Davies (1934) described one of the first methods of estimating aphid populations in the field; he counted the aphids on lower leaves chosen at random, and expressed the opulation as aphids per 100 leaves. Simpson (1940) reported that the species of aphids on potatoes in Maine differed in their distribution on the plant; to obtain a better estimate of the population, he modified Davies' method and counted the aphids on equal numbers of leaves selected at random from the top, middle, and bottom portions of the plants. Other workers (Joyce, 1938; Hansen, 1941; Whitehead, 1943; Thomas and Jacob, 1943; Staniland, 1943; Jacob, 1944; Doncaster ana Gregory, 1948; Münster, 1948) used various methods of selecting leaves for the sample but continued to express the population as aphids per 100 leaves. Much of the earlier work was in the form of surveys to determine the population of aphids above which the maintenance of healthy seed stock was not a practical proposition.

Periodic outbreaks of the large aspen tortrix, Choristoneura conflictana (Wlkr.) severely defoliate trembling aspen, Populus tremuloides Michx., in parts of Manitoba and Saskatchewan. The inadequacy of information on the insect prompted further investigation of its life history and the factors affecting its abundance. Field studies were conducted in Northern Manitoba and Saskatchewan, where from 1950 to 1954 the insect was found at various population levels.

The efficacies of cypermethrin, deltamethrin, permethrin, endosulfan, methoxychlor, carbofuran, chlorpyrifos, dimethoate, and malathion were evaluated against the wheat midge, Sitodiplosis mosellana (Géhin). Methods are described for evaluating damage and protection in individually collected wheat heads and whole plants. Weighted values from whole plants provided the best indication of kernel protection and yield response.

Whole plants contained three main types of wheat heads (primary heads, first tillers, and second tillers) which differed in their frequencies, kernel numbers, and developmental times. The latter indicated that the chronology of midge attack, status of midge infestations during spraying, and spray coverage also differed in the head types.

Insecticides provided different levels of kernel protection within and among the various head types. The majority of primary heads emerged before spraying and harbored midge eggs at spraying. In these wheat heads, chlorpyrifos, endosulfan, and malathion provided significantly better kernel protection (60–75%) than permethrin, deltamethrin, and cypermethrin (<7%). The results suggested that the more effective kernel protectants permeated the spikelet and controlled the eggs and/or newly hatched larvae. Kernel protection in the primary heads was closely related to insecticide volatility. Conditions were different in most first tillers and second tillers which emerged after spraying. In these wheat heads, poor spray coverage and short residual activity against adult midge appeared to limit kernel protection by all insecticides.

Alternatives to synthetic insecticides are desirable for management of diamondback moth, Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae), an insect pest of global importance. Many essential oils derived from aromatic plants have demonstrated toxicity and behaviour altering effects on insect pests, and are considered low-risk alternatives to synthetic insecticides. We conducted laboratory experiments to determine the biological activity of several low-cost, commercially available essential oils against P. xylostella. Experiments testing ovicidal effects, larvicidal effects, larval feeding deterrence, and adult oviposition deterrence were done with essential oils derived from Artemisia abrotanum Linnaeus (Asteraceae), balsam fir (Abies balsamea Linnaeus (Pinaceae)), black pepper (Piper nigrum Linnaeus (Piperaceae)), eucalyptus (Eucalyptus polybractea (Baker) (Myrtaceae)), garlic (Allium sativum Linnaeus (Amaryllidaceae)), rosewood (a blend of different oil constituents), tansy (Tanacetum vulgare Linnaeus (Asteraceae)), and thyme (Thymus zygis Linnaeus (Lamiaceae)), using concentrations of 1, 2.5, and 5% v/v. Although all essential oils had some level of bioactivity against certain P. xylostella life stages, essential oils from garlic, rosewood, and thyme were most effective overall, demonstrating significant ovicidal and larvicidal activity, as well as deterrent effects on larval feeding and settling behaviour, and adult oviposition. Although variable phytotoxicity was observed with essential oils at 2.5% and 5% v/v concentrations, the results suggest that rosewood, garlic, and thyme essential oils have potential in management of P. xylostella.

Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), populations were studied on white fir at four areas in central Sierra Nevada mountains of California during 1971–73. Life tables were constructed for four populations in El Dorado County. The number of eggs per egg mass decreased and the percentage eggs parasitized doubled with declining moth populations. Hymenopterous parasitoids were collected from all immature stages of the moth: one egg parasitoid, Telenomus californicus Ashmead, six species of larval parasitoids, principally, Hyposoter sp., and 13 species of larval–pupal parasitoids. Tachinids were predominant and accounted for 73% of the parasitoidism of the cocoons in 1971. The apparent mortality of female pupae due to the parasitoid complex was greater than 97% in 1971 and 75% in 1972. One population in Placer County collapsed in 1971 apparently due to a combination of heat exhaustion and low levels of virus infection. Other defoliators, spiders, and several predatory insect species were collected from the foliage samples simultaneously with the tussock moth during larval sampling. Twelve species of "free living" spiders which could be capable of preying on the defoliator complex of white fir were collected. Parasitoids and predators appear to be potentially important biotic factors at low to moderate host population levels. This is the first recorded case where an agent other than the nucleopolyhedrosis virus has been responsible for the collapse of a Douglas-fir tussock moth population.

Almost 40% of the cells of Megachile rotundata (F.) from the earliest completed tunnels in the hives produced as second-generation bees. This percentage rapidly decreased in the later completed tunnels. The difference between wing venation of bees that emerged in spring and of second-generation bees that emerged in summer appears to be related to voltinism.

We investigated pollen and nectar foraging of honey bees, Apis mellifera L., from pollen-poor and pollen-rich, small and large colonies in blooming highbush blueberry, Vaccinium corymbosum L. cv. Bluecrop fields. The proportion of pollen foragers differed significantly between pollen-rich and pollen-poor colonies after storage levels were manipulated, but foraging and pollen stores returned to similar levels within a week. No differences were found in small colonies, although the proportion of pollen foragers was high (46% and 45% from pollen-rich and pollen-poor colonies, respectively). Only 7.6% of pollen foragers carried Vaccinium sp. pollen in their loads independent of treatment, day, and colony size, whereas 60.8% of nectar foragers carried up to 100 tetrads of Vaccinium sp. pollen on their bodies. The average proportion of Vaccinium sp. pollen carried by nectar and pollen foragers per day and treatment was less than 10%. Our research indicates that when colonies are placed in fields of blooming blueberry flowers, pollen foraging is stimulated in large colonies with stores that are pollen poor, but predominantly for pollen types other than blueberry. This research indicates that nectar foragers are the major visitor of highbush blueberry cv. Bluecrop and suggests that increasing the number of nectar foragers rather than pollen foragers would result in more honey bees foraging on highbush blueberry, in particular cv. Bluecrop.

The concept of degree-day summation was employed in three models of malthusian growth predictive over a range of temperatures. When supplied input data from life table studies conducted at five constant temperatures, the models were able to predict the magnitude and pattern of growth of populations of Tribolium confusum Duval reared under malthusian conditions. The stochastic model, moreover, revealed that the series of chance events found in the course of population growth could explain differences between one population and the next. When computer experiments on the importance of various life table parameters were run, the models revealed the overwhelming importance of time taken to mature on the rate of population growth. The level of fecundity was next in order of importance while population growth was least sensitive to changes in survivorship.

A field study was carried out to determine the intracrown distribution of the balsam fir sawfly, Neodiprion abietis Harris (Hymenoptera: Diprionidae), throughout the season on balsam fir, Abies balsamea L. (Pinaceae), during the first 2 years of an outbreak in western Newfoundland. Eggs were usually laid one per needle on current-year shoots, and the following year, newly emerged larvae usually initiated feeding on the same shoots. Balsam fir sawfly larvae were gregarious on needle and shoot levels in the early instars but gradually became solitary as larvae developed. The process of becoming solitary was not due to the increased physical area required for the growing larvae as some older individuals, in mainly solitary stages, were seen feeding together. Unlike the continuous change from gregarious to solitary at the needle and shoot levels, the seasonal variation in larval density among whorls varied in an inconsistent manner. The majority of early-instar larvae were found in the middle crown, but on at least one date in both years the majority of late instars were in the lower crown. Seventy-five percent of crawling larvae trapped within the crown were third and fourth instars, suggesting that changes in the intra-tree distribution are due to larval movement.

Laricobius nigrinus Fender is being reared for release as a biological control agent for hemlock woolly adelgid (HWA), Adelges tsugae Annand. HWA is an introduced insect lethal to hemlock trees (Tsuga canadensis (L.) Carr. and T. caroliniana Engelm.) in the eastern United States. In nature, the predator (Laricobius nigrinus) and its prey (HWA) undergo a dormant period in the summer (aestivation). In the laboratory, the aestivation of L. nigrinus has not been synchronized with that of HWA, resulting in significant predator mortality. Four factors (genetics, temperature, photoperiod, and moisture) were investigated for their effects on aestivation in L. nigrinus. Both the number of individuals and the time at which they emerged from aestivation were measured in response to these factors. Temperature was the most important cue for termination of aestivation, and photoperiod was a modifying factor. High temperature and long day length delayed emergence and high moisture levels resulted in greater emergence but did not affect emergence time. Genetics, as represented by broods, was not a major factor in aestivation termination. These results have led to improvement in rearing L. nigrinus, since emergence from aestivation can now be synchronized with the active period of HWA. Increased success in rearing has expedited field releases of L. nigrinus in the eastern United States.

Available information on the interaction between Sitka spruce weevil, Pissodes strobi (Peck), and its host Sitka spruce, Picea sitchensis (Bong) Carr., is examined. Based on a theoretical consideration of this information, a new mechanism is proposed to explain the resistance exhibited by some of the genetically distinct individuals of some provenances of this species. Experimental evidence is presented to show that resistant trees can sufficiently affect P. strobi reproduction and progeny development and survival to reduce this pest’s ability to kill the leaders of these trees when challenged with weevils containing already mature eggs. Our mechanism also provides an explanation as to how weevils are able to avoid attacking and reproducing on resistant trees in which their progeny would fail.

In the course of recent field studies in southern Alberta on the behaviour of adults of the sugar-beet wireworm, Limonius californicus (Mann.), it has been observed that the males spend much of their time after emergence resting on small clods of earth with their heads pointed upward into the breeze and with their antennae waving as though testing for odours. When they appeared to scent a female they moved into the breeze, crawling or flying, depending on the velocity of the wind. As they neared the female they became increasingly agitated, but when in close proximity to her they seemed confused and often passed within an inchof her. Eventually one of them located her and mating occurred almost immediately. The remaining males finally dispersed after crawling repeatedly around and over the copulating pair. These observations suggested that the females, soon aftcr emerging, release a sex attractant.

The signs of an Empusa muscae Cohn infection in dead flies were described over two centuries ago by de Geer (Kirby and Spence, 1826), who, however, attributed the cause to some factor other than a microorganism. Though the validity of the name Empusa has often been questioned, it is used in this paper following the suggestion by MacLeod (1956).

The following account deals with the transmission of E. muscae to species of Diptera under controlled laboratory conditions.

This study examined the dose-dependent effects of synthetic honey bee queen mandibular pheromone on the inhibition of worker ovary development. The range of doses examined was from 10−3 to 10 queen equivalents (Qeq) per day for 43 days; 1 Qeq was the amount of pheromone in an average pair of queen mandibular glands. Ovary class and ovariole number scores were used as estimates of worker ovary development. Queen mandibular pheromone did not inhibit ovary development in workers at any dose.

Predators that have fed on Panonychus ulmi (Koch) and Bryobia arborea Morgan and Anderson can be distinguished by the orange and reddish carotenoid biochromes derived from the prey. Predation on the two species of mites cannot be clearly separated. The predators are squashed on filter paper and the pigments separated by circular chromatography in a mixture of one part of zylene to four parts of white kerosene. The mite pigments are considerably altered during digestion in the predators. The method does not reveal the number of mites consumed by a predator, owing to differences in the pigment content of the various stages of the prey and in the time the pigments are retained in the predators.