This paper presents a sampling plan for estimating numbers of H. postica larvae in the spring growth of alfalfa. A 6-stem bouquet of foliage formed an appropriate sample unit. The pattern of counts for all four instars conformed to the negative binomial distribution, and variance analysis for 89 sets of data revealed that differences between block, plots, and quadrats generally were not significant. For moderate levels of infestation (ca. 12 larvae per bouquet), estimates with acceptable precision may be obtained by taking a single 6-stem bouquet from each of 16 randomly selected ft2 (0.9m2) quadrats within a field, at a total cost of 120 man-minutes.

Adult silkmoths captured in northwestern Ontario and tentatively identified as Hyalophora columbia (Smith) were found to resemble H. gloveri nokomis (Brodie) which occurs as far east as Winnipeg, Man. Habitat studies showed that the larvae of the northwestern Ontario moths are not strictly larch feeders as are the larvae of typical H. Columbia.

The dorsal thoracic tubercle colour of typical fifth instar H. Columbia larvae is red. Matings between typical H. Columbia and H. cecropia (L.) have produced fifth instar larvae with only reddish-orange tubercles. However, matings of male moths from northwestern Ontario with H, cecropia females have produced fifth instar larvae with reddish-orange, light orange, or yellow dorsal thoracic tubercles. Further matings of northwestern Ontario males with H. euryalis (Boisd.) and typical H. Columbia females have established the presence in northwestern Ontario of a colour polymorphism of which the phenotypic colour components are red, reddish orange, and yellow.

The fifth instar dorsal thoracic tubercle colour of H. gloveri nokomis larvae is yellow and it is proposed that the yellow tubercle colour of the northwestern Ontario larvae has originated from the influx of genes from the nearby H. gloveri nokomis population.

The evidence presented in this paper points to the existence of an intergrade population between H. gloveri nokomis and H. columbia in northwestern Ontario.

Mortality of the European red mite, Panonychus ulmi (Koch), on peach leaves was directly related to the uniformity of distribution and amount of deposit of dicofol for up to 4 days after the spray was applied. Mite mortality decreased rapidly from the 4th to the 11th day after spraying, whereas the dicofol detected by chemical analysis decreased at a slower rate. The minimum deposit of dicofol for 100% kill of the mite, immediately after spraying, was between 0.3 and 0.8 μg/cm2, depending upon uniformity of coverage. Doubling the dose did not increase the mortality then or later. Fourteen days after spraying, the dicofol deposit on some leaves was still 0.7–0.8 μg/cm2 but there was practically no mite mortality.

A single 7.5-min injection of 0.6 p.p.m. of methoxychlor into the North Saskatchewan River eliminated 100% of instars 3 to 6 inclusive of the larvae of Simulium arcticum Mall, from sites 40 and 80 km downstream, 91% at 121 km, and 66% at 161 km. Ninety-six per cent of the larvae less than 1 mm long were removed from the 161-km site. Plecoptera larvae were similarly affected. Chironomidae, Ephemeroptera, and Trichoptera were least affected.

The treated portion of the river was rapidly repopulated by insect larvae. None of the pretreatment taxa disappeared and in fact many new ones appeared, during the 10 weeks immediately following the treatment. In all four sites examined in the treated portion of the river, population densities of Chironomidae larvae larger than 1 mm long equalled or surpassed the pretreatment densities within 1 to 3 weeks, Ephemeroptera within 1 to 4 weeks, Trichoptera 1 to 7 weeks, Plecoptera 4 to 5 weeks, and Simuliidae in 2 to 10 weeks. Populations of larvae smaller than 1 mm long were generally restored more rapidly. Procedures for an annual abatement programme for S. arcticum in the Saskatchewan River are outlined.

The life history of the European earwig at Vancouver, B.C., is described and divided into two periods: the nesting phase and the free-foraging phase. Seasonal changes in population characteristics are documented and compared in sparsely and densely vegetated habitats. The developmental rates, population sizes, and sex ratios, but not the body weights, differ between the two habitats. Suggested reasons for these differences are advanced.

The number of male and female first generation Panonychus ulmi (Koch) were recorded from 13 apple orchards representing widely different levels of mite infestation on four different varieties. The average percentage of males was 27.5. Statistically significant differences were found among orchards, varieties, observers, and their interactions. No relationship between sex ratio and population density was evident.

The life cycle of Ironoquia punctatissima (Walker) is described for a population occurring in a temporary stream in southern Ontario. A description of the hitherto undiscovered pupa is also given.

Ooencyrtus ennomophagus n. sp., an egg parasite of the elm spanworm, Ennomos subsignarius (Hübner), from Connecticut, U.S.A., is described and illustrated.

An outbreak of the forest tent caterpillar began in northern Minnesota in 1964 and ended abruptly in 1972. During 1968–71 when egg densities ranged from 1 to 9 million per acre, caterpillars caused virtually complete tree defoliation in all study plots. As a result, tree stem densities and basal areas were reduced per plot by 41 and 27%, respectively. Tree mortality was more severe on plots having higher water tables. Graphical and components of variance analyses both showed that: (1) variations in annual egg densities were due mostly to variations in survival during the egg to 30-day larval stage (SI) and secondly to variations in survival during the 30-day larval to adult stage (S2), (2) S2 tended to change in the opposite direction from S1, (3) the net result was a tendency to produce a constant amount of eggs per unit area. Variations in S1 were due primarily to pharate larval mortality and mortality of larvae 2–3 weeks after hatch while variations in S2 were due mainly to unmeasured mortality factors such as starvation, disease, dispersal, etc. Survival during the egg stage (SE) and fecundity (F) varied significantly by years, but not by plots and both were apparently related to weather conditions. Plots of two simultaneous equations were presented to demonstrate the nature of population change in relation to the densities of eggs and 30-day larvae per acre.

To relate the various details of the cluster fly life cycle which have recently appeared in the literature, a preliminary mathematical model is constructed When used to interpret the population data of De Coursey, the relationships of the model were shown to be at least qualitatively sound. From an examination of the parameters which modify the components of the model, some possible control measures are suggested.

This study had dual objectives: to select a series of insecticides toxic to the bertha armyworm, Mamestra configurata (Walk.), and to determine susceptibility of the various developmental stages to insecticides. Pupae were collected from infested rapeseed fields in Alberta and a laboratory rearing procedure suitable for production of large numbers of insects was devised. The direct contact toxicity of 50 insecticides to third-stage larvae was assessed. Methomyl and DDT were included as standard insecticides. None of the experimental insecticides was as toxic as methomyl but about one half were more toxic than DDT. Tests with representative organochlorine, organophosphorus, and carbamate insecticides indicated that all caused rapid knockdown of third-stage larvae. There was no evidence of subsequent recovery. After the life history of the bertha armyworm under controlled environmental conditions was determined, tests were conducted to ascertain the susceptibility of the various developmental stages to methomyl, chlorpyrifos, leptophos, and methidathion. Eggs and first and second stage larvae were more susceptible to direct contact applications of the insecticides than were the later larval stages, pupae, and adults.

A 2-year study on management of apple pests was carried out on six orchards in the interior of British Columbia. Sample techniques and treatment thresholds were satisfactory for most pests with the exception of fruittree leafroller, Archips argyrospilus (Walker), western flower thrips, Frankliniella occidentalis (Pergande), and the mirid Campylomma verbasci (Meyer). The number of chemical sprays per orchard averaged eight when the study was initiated. In 1973, the sprays required for pest control were reduced to an average of 5.6 per orchard, and in 1974, this figure was further reduced to 3.1. This reduction in chemical sprays was accomplished without an increase in insect or mite injury to fruit or foliage.

Chilled adult codling moths, Laspeyresia pomonella (L.), are exposed to a cloud of Day Glo® fluorescent powder as they pass through a rotating screen drum.

1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)-urea when ingested by the last two larval instars of the spruce budworm, Choristoneura fumiferana, inhibits cuticle development leading to morphogenetic deformities in the pupal stage. Laboratory and greenhouse studies indicate that this material could be used to control natural populations of spruce budworm.

The history of placement of the Heterocheylidae Trägårdh, 1950, is reviewed. The family does not belong in either the Anystoidea or the Cheyletoidea, and instead is placed in its own superfamily, Heterocheyloidea Trägårdh new status, which in turn is transferred to a position beside the cohort Tarsonemina in the supercohort Heterostigmata. The placement of Heterocheylidae in the Heterostigmata is based upon the presence of paired stigmatic openings on the anterolateral margin of the dorsum of the propodosoma, the subcapsular form of the gnathosoma, the structure of the palpi, the sequence of dorsal setae and tergites of the hysterosoma, and other characters. Diagnoses for the Heterostigmata and the Heterocheyloidea are given. The relationship of the Heterocheyloidea to the Tarsonemina is discussed.

Using explosives, 93 grand fir were examined for root decay and bark beetle activity. Ninety-six per cent of the trees attacked by bark beetles also had root rot. From the data it appears that root disease is an important factor in predisposing fir to attack by bark beetles. Significant relationships were found between the presence of root decay and both the incidence of beetle attack and the number of attacks. No such relationship could be found concerning the success of beetle attacks. The question of bark beetles as vectors of root disease was not considered.

Evidence from studies in large field cages indicated that odor from virgin male apple maggot flies, Rhagoletis pomonella (Walsh), was attractive to virgin females. Whether the principal role of this odor in mating behavior is in fact that of a female attractant or rather that of an aphrodisiac is uncertain and awaits further study.

The fecundity of apple maggot females was significantly greater (P <.05) on apple than on black ceresin wax domes. Eggs/female laid in apple varied from 24.8 to 318.1 and that in domes from 0.4 to 27.5. Mated females did not lay significantly more eggs than virgins and those confined in groups did not lay significantly more than those confined individually. These findings do not concur with those reported in the literature.