In laboratory and field studies with the codling moth, Cydia pomonella (L.), TH 6043 and TH 6044, experimental benzoylphenyl urea chitin-synthesis inhibitors, were as effective as diflubenzuron in reducing egg hatch and subsequent larval entry when eggs were deposited on previously treated fruits or foliage. All three compounds exhibited extended residual activity, with significant reductions in egg hatch occurring over a 19-week period. TH 6045 exhibited little activity against codling moth. All compounds tested were relatively ineffective in reducing egg hatch or subsequent larval entry when they were applied topically to deposited eggs, except for the red ring stage of development which was slightly affected.

Mixtures of the juvenile hormone analogue (JHA) methoprene and each of three benzoylphenylureas (BPUs) were fed to sixth-instar western spruce budworm, Choristoneura occidentalis Freeman. The BPUs tested were diflubenzuron, BAY SIR 8514 (N-[(trifluoromethoxy)phenyl]carbamoyl-2-chlorobenzamide), and EL-127063 (N-[[[5-(4-bromphenyl)-6-metnyl-2-pyrazinyl]amino]carbonyl]-2-chlorobenzamide). Mixtures consisted of JHA:BPU combined in 1:9 proportions. Ingestion of methoprene combined with BAY SIR 8514 or diflubenzuron resulted in significantly lower mortality than expected under a simple model of uncorrelated, independent action. Ingestion of the mixture of methoprene and EL-127063, however, resulted in significantly enhanced toxicity over the upper response range (> 50% mortality).

Spatial dispersion of potato aphids was studied in fields of processing-tomatoes for 2 years to develop a sequential sampling scheme for the aphid. Potato aphids were found on upper, middle, and lower leaf strata in the percentages 60, 31, and 8. Dispersion was clumped, apterates more so than alates. Among-plant variance was generally greater than within-plant variance. There was a good linear relationship between mean crowding and the population mean and an excellent linear fit between log variance and log mean on all leaf strata for green and pink forms of the aphid and for alates and apterates. The log variance – log mean relationship was used as a basis for sequential sampling.

Earlier attempts to correlate spruce budworm, Choristoneura fumiferana (Clem.), outbreaks and weather conditions were usually carried out by comparing seasonal data and spruce budworm outbreak development in broad terms: it was found that warm, dry weather favored outbreak development, while cool, wet weather retarded development. In this paper, laboratory experiments and historical data are examined to determine the effect of temperature and precipitation on second-instar larvae, just prior to and after spring emergence. Results tend to show that prolonged rain and freezing temperatures during and shortly after emergence are detrimental and may, in some cases, have a profound impact on outbreak development.

A pilot black fly control program using Bacillus thuringiensis var. israelensis on a small stream system near St. John's, Newfoundland resulted in a 70% or greater population reduction of adult black flies from the previous year. The species present in the system were Prosimulium mixtum, Stegopterna mutata, Eusimulium vernum, Simulium tuberosum, S. venustum/verecundum complex, and S. vittatum. The formulation used was Teknar® flowable concentrate (Sandoz Inc.) rated at 600 ITU/mg which proved effective against the larval stages of all black fly species at a dose of 10 ppm for 1 min. The results indicated that this agent will be effective if applied at the appropriate locations and times. The 1-min dose was practical except in very cold water (0°–7 °C) where a 5-min or longer dose may be required. The unpredictable relief pattern of the northern streams resulted in a highly variable downstream carry for the B.t.i. Therefore application sites must be determined by a stream survey and not just from discharge characteristics.

Superparasitism and multiple parasitism of the pea aphid, Acyrthosiphon pisum (Harris), by the solitary hymenopterous parasites Aphidius smithi Sharma & Subba Rao and Praon pequodorum Viereck were studied in the laboratory. In intraspecific competition, an older larva usually eliminated a younger one; exceptions to this rule depended on the relative age difference and developmental stage of the competitors. In interspecific competition, P. pequodorum was intrinsically superior to A. smithi, regardless of the latter's age. The stage of host parasitized and the number of competing larvae had no significant effect on the outcome of the contest. A. smithi females discriminated against aphids previously parasitized by a conspecific female or by P. pequodorum, the degree of oviposition restraint increasing with the time between ovipositions. P. pequodorum females attacked aphids already parasitized by A. smithi, regardless of the age of the Aphidius larva, but avoided oviposition when the aphid contained a Praon larva or embryo. The rate of embryonic development is shown as a major factor in contest-type competition between first-stage larvae.

The success of introducing natural enemies for biological control was found to be about 75% higher employing new parasite–host (predator–prey) associations than those based on long-evolved associations between parasites and hosts. The lack of evolved interspecific balance in new species associations appears to explain the higher success rate. New exploiter–victim associations expand opportunities for the biological control of both introduced and native pests and should be used as the preferred method in selecting biological control agents.

Adult flies of the apple maggot, Rhagoletis pomonella (Walsh), were monitored for 6 years at Guelph, Ontario using aerial and ground-emergence traps. Two degree-day (°D) models to predict adult emergence were tested. Fifty percent of the adults were captured in an average of 809 ± 50 (SD) °D8.7 and first capture was at 638 ± 60°D6.4. Degree-day models which have been proposed previously and those developed in this study were only slightly more accurate than average calendar date for predicting adult emergence. Differences in °D requirements for emergence in each year were correlated with the length of cold period and the correlation suggested that the length of cold period preceding morphogenesis affects either the number of °D required to complete postdiapause development or the threshold temperature for development.

The rate of hatch of overwintered eggs of the strawberry aphid, Chaetosiphon fragaefolii (Cockerell), at five temperatures in controlled environment chambers was used to determine the thermal threshold of development. Samples of eggs were taken from two field locations several times before hatch. These samples were subdivided and placed into two or three different constant temperature chambers. The day-degree requirements for hatching from the time of collection were estimated. These estimates corresponded to the number of day-degrees actually accumulated in the field between the time of egg collection and the time of hatching.

This method of simulating the effect of temperature on egg development was an accurate method of predicting the time of hatch in the field at least 3 weeks prior to the observed time.

Adult tipulids were collected at weekly intervals in a southern New York open woodland. Sweeping, light trapping, and Malaise trapping yielded 4003 crane flies representing 125 species. The 25 most common species were identified and enumerated. The Malaise trap data were used to examine phenology, diversity, and species evenness. Further numerical analysis with the Malaise trap data indicated similarity among collecting periods. These results were used to outline the seasonal subcommunities that existed over a 2-year period.

The eruption of Mount St. Helens in southwestern Washington on 18 May 1980, ejected tons of volcanic ash that settled over large portions of eastern Washington, northern Idaho, and western Montana. Although most of these areas received only a light dusting, the heaviest deposits in the central path of the ash plume formed a layer of ash 5 to 8 cm thick (Cook et al. 1981). The ash consisted of microscopic, jagged particles that were highly abrasive and easily damaged the epicuticular wax layer of insects, causing desiccation and eventual death (Brown and Hussain 1981). The impact of ash on a variety of agricultural-related insects in the fallout area has been described (Akre et al. 1981; Fye 1983; Howell 1981; Johansen et al. 1981; Klostermeyer et al. 1981). This note reports the effects of ash on small larvae of a major forest defoliator, the Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), as determined in laboratory and field experiments.

Since 1978 several experiments with aqueous formulations of acephate have demonstrated its potential as an effective and economical control agent for grasshoppers on rangeland (Onsager and Mazuranich 1979; Foster et al. 1981a,b). While it has been generally accepted that grasshopper mortality arises primarily from the ingestion of acephate (Chevron Chemical Co., unpub. data), the extent of the mortality attributable to direct deposition of the spray on the insect or ingestion of the spray remains undefined. The following experiment was conducted to determine grasshopper mortality levels for the methods of exposure (ingestion of sprayed vegetation, direct deposition of the spray on the insect, and a combination of ingestion and direct deposition) which result from an aerial treatment of rangeland with acephate. Any mortality attributable to contact between the insect and sprayed vegetation or ground was not determined because of difficulties in preventing the insects from feeding while being exposed to sprayed vegetation. Studies with malathion, another organophosphate used for grasshopper control, showed that sprayed soil contributed minimally to the total mortality of grasshoppers (Pfadt et al. 1970).

p. 228, Figure 1. La frontière entre le Québec et la province de Terre-Neuve et Labrador est omise.

p. 705, Table 1, 3rd column, 2nd line, for 23 ± 1.7 read 98 ± 1.7.