Populations of two abundant coccinellid species, Coleomegilla maculata lengi Timberlake and Hippodamia tredecimpunctata tibialis Say, responded rapidly to corn leaf aphid populations [Rhopalosiphum maidis (Fitch)] once the aphids became exposed to predation when the plants tasselled. Coleomegilla m. lengi oviposited at lower densities of aphids than did H. t. tibialis but H. t. tibialis was shown to have a greater numerical response than C. m. lengi at high densities of aphids due to its greater fecundity. The numerical response of the coccinellids by oviposition was linear with a lag of 1/2 week behind the aphid population.

Average duration of the larval stage of Syrphus corollae Fab. reared at 20 ± 1 °C decreased linearly with increase in amount consumed from 9.2 days with 40.9 cal consumed/larva to 7.9 days at 78.1 cal/larva. Mean weight of pupae and percentage emergence of adults increased with calories consumed. No eggs were laid by flies developed from larvae which consumed less than 54.6 cal of energy, equivalent to 38 aphids. Average fecundity increased linearly with consumption up to 81.6 cal/larva (= 58 aphids). Mean reproductive output was 3.2% of larval consumption above 55 cal but decreased as larval consumption increased. When food was scarce, fecundity decreased because pupae, and therefore ovaries, were smaller. Larvae consumed as much as possible in the time available rather than pupating after consuming a minimal amount.

The trails of Camponotus modoc Wheeler follow perennial routes. The ants orient along these using both chemical and visual cues. If the chemical cues are disrupted the ants reform the trail while orienting by visual cues. They can respond to the same visual cues after at least 12 h, and since no evidence was found that the chemical cues survive the winter, probably after 6 months.

Spray and feeding bioassays of acephate and carbaryl were conducted with each of the six instars of the western spruce budworm, Choristoneura occidentalis Freeman. Dose-mortality regressions were used to estimate overall relative susceptibility. Small differences in overall susceptibility of the six instars to acephate and large differences to carbaryl were observed. Application of carbaryl so that it would be present when second instars emerge from their hibernacula may maximize efficacy by minimizing the tolerance-instar effect. The efficacy of acephate may be relatively unaffected by instar-related changes in tolerance.

In Hemiarctic northern Quebec (55°00′N; 69°55′W), one of the three main herds of woodland caribou (Rangifer caribou) of Central Ungava, cross the lake Delorme area. During their annual migration, caribou make many persistent tracks which serve as mosquito larval breeding sites for four species of snowmelt Aedes. There are no appreciable differences in species composition, the relative abundance and the density of the mosquito populations in these tracks, and in the natural shallow pools of the two bog plant associations (Carex oligosperma and Chamaedaphne calyculata) crossed by the caribou trails.

Culex pipiens (L.) and Culex restuans Theo. populations were monitored at Guelph, Ontario, throughout the summer of 1978, by egg raft collections from artificial pools and adult collections using CO2-baited, CDC light traps. Three to four major generations of C. pipiens were evident with first oviposition on 17 May and last on 15 October. C. restuans was abundant during the spring and early summer while C. pipiens was most abundant in mid-July and August. Neither species showed greater attraction to pools containing a reported ovipositional attractant, decanoic acid. The use of oviposition pools was found to be an efficient, inexpensive, and sensitive technique for monitoring populations of Culex spp.

An assessment of toxicological responses among the Choristoneura species occidentalis, viridis, and fumiferana indicated that within-species variation in response to acephate may be as large as between-species variation. Studies of C. occidentalis sibling groups suggest that allozyme variation at the second esterase locus may be related to differential sensitivity to acephate. Use of genetic markers to forecast population response in control programs is discussed.

Direct contact toxicity data were obtained with selected insecticides on 24–48 h old adults of insecticide-susceptible onion maggot, Hylemya antiqua (Meigen), cabbage maggot, H. brassicae (Bouché), and seedcorn maggot, H. platura (Meigen); and on third-stage darksided cutworm, Euxoa messoria (Harris). All insecticides were highly toxic to onion maggot flies, with the order of toxicity being: cypermethrin > chlorpyrifos > fenvalerate > permethrin > parathion > isofenphos > terbufos. Chlorfenvinphos was 1.4 × more toxic to cabbage maggot adults than parathion; the pyrethroids were less toxic, with fenvalerate being 1/13 as toxic as parathion. The order of toxicity of insecticides tested on seedcorn maggot flies was: diazinon > cypermethrin > chlorpyrifos > fenvalerate > permethrin. With the darksided cutworm, DDT and leptophos were 1/10 and 3/4 as toxic as chlorpyrifos, while cypermethrin, fenvalerate, permethrin, and decamethrin were ca. 10, 11, 12, and 120 × more toxic, respectively.

Probit analysis of the dosage response of codling moth stages to methyl bromide indicated that adults were most, and pupae, least susceptible. Eggs were more resistant than cocooned larvae which were more resistant than larvae in fruit. There were no differences in susceptibility of the larval instars to methyl bromide. The rate recommended to kill larvae in fruit (32 g/m3 for 2 h) also killed eggs.

The subgenus Chrysonotomyia Ashmead s. str. is reviewed. Eight species are recognized and three new species are described: C. baliosa n. sp., C. solidaginis n. sp., and C. cunicularia n. sp. Keys to species, list of hosts, list of misidentified species, and distribution records are included.

A laboratory system was developed that allowed populations of the house fly, Musca domestica, and its hymenopterous, wasp parasitoid, Nasonia vitripennis, to interact and fluctuate in numbers, subject only to an upper limit on Musca density. In one (experimental) treatment, the selection pressure from Nasonia was allowed to operate, while in the control all Musca adults were replaced in each generation by individuals from a Musca population not exposed to Nasonia. Evolution for resistance of Musca to Nasonia became noticeable within four generations in the experimental treatment. Measured changes finally included increased fly pupal weight (although larval development period was not allowed to increase), less time spent as pupa, increased pupal mortality, and reduced fecundity of adults. Total per-generation increase of both control and experimental Nasonia was much reduced on experimental compared with control Musca. This was caused by reductions both in the longevity of female Nasonia and in the number of progeny they produced each day. From early in the experiment the increased resistance of Musca produced lower Nasonia densities in the experimental treatment. During the first 20 or so generations no difference could be detected in mean Musca density between the two treatments. After that time the density of adult Musca became greater, and fluctuated less, in the experimental than in the control treatment. This situation continued until the experiment ended at 50 generations.

A new genus and two new species of Phloeocharinae are described and illustrated: Dytoscotes, new genus, pacificus from Oregon, and Phloeocharis californica from California. The biology of the two species is briefly discussed. A key to the Nearctic genera of Phloeocharinae is given.

A new species Clepsis (Siclobola) firthana is described from the northern Yukon Territory, Canada. Morphologically this species is closely related to the European C. strigana (Hübner) and the North American C. clemensiana (Fernald). Genitalic characters are given to distinguish C. firthana from the North American C. kearfotti Obraztsov and C. moeschleriana (Wocke) (which have similar markings), and C. clemensiana (Fernald).

Phosmet (Imidan 50% WP) applied at 1.22 kg a.i./ha controlled the codling moth, Cydia pomonella (L.), apple maggot, Rhagoletis pomonella Walsh, and plum curculio, Conotrachelus nenuphar Herbst, in Ontario apple orchards for more than 3 weeks. Although rain removed phosmet deposits and climatic conditions varied widely during 1971–76, results consistently showed that good pest control was obtained. Satisfactory results were also obtained with azinphosmethyl (Guthion 50% WP) applied at 0.45 kg a.i./ha. Toxicological studies showed that phosmet deposits on the lower surface of apple leaves produced 38–100% mortality of first instar codling moth larvae 15 days after application depending on the time the pesticide was applied. Fifty per cent and 95% lethal residues were 0.18–0.68 μg/cm2 and 0.50–1.36 μg/cm2 of leaf surface, respectively. The toxicity of the residues declined considerably 22 days after application.

A phosmet deposit of 0.5 μg/cm2 15–22 days after spray application is suggested as the minimum level required to obtain an economically acceptable level of control in the field.

In the course of my search for Miridae and Anthocoridae in Nova Scotia in 1976, I collected a series of 33 bugs which proved to be the females of Loricula pselaphiforrnis Curtis, family Microphysidae. The species was collected on the trunks of European beech, Fagus sylvatica var. purpurea Ait., at Point Pleasant Park, Halifax, 22 July 1976. The bugs were first observed as tiny bumps on the trunks, blending perfectly with the bark and small patches of lichens. At first sighting the bumps were thought to be tiny spiders or their egg cases. When disturbed they moved a short distance and again remained motionless. All were brachypterous females, no males were collected, and no specimens were collected by beating the branches. Although other species of tree trunks were examined, no bugs were found. The bugs may have been introduced into this country with nursery stock importations of beech or some other horticultural plants.