A study was conducted to quantify the relationship between ambient air temperatures and adult internal body temperatures of three rangeland grasshoppers near Three Forks, MT. Results show a strong non-linear relationship between air and body temperatures over the range of temperatures normally encountered during the adult stage (approximately 2–42°C). Observations and historical data indicate the considerable influence of behavioral modification that results in grasshoppers attempting to maintain an optimal temperature range that minimizes development time. Results should be of interest to insect ecologists and those studying grasshopper biology and population dynamics.

Four genera and 9 species of ants were collected by pitfall traps in a spruce budworm-infested forest of northern Maine. Myrmica detritinodis and Camponotus herculeanus were most abundant. In 1977, significantly more individuals and species were trapped in dense spruce-fir stands than in either uncut residual or clearcut strips. In 1978, clearcut-strip and dense-stand means were nonsignificant for individuals and species, but significantly more individuals and species were trapped in clearcut than in uncut residual strips. Ants were active during the spruce budworm’s developmental stages. Diversity of ant species was generally greater in dense stands than in strip-clearcut areas. Individuals were distributed unevenly among species but more evenly in dense stands than in strip-clearcut areas (residual + clearcut strips). Coefficients of community (CC) and percentage similarity (PS) values indicated ant species and individuals shared forest conditions in common; however, the most dissimilar neighboring habitats (uncut residual and clearcut strips) had few species in common. Neither age of strip clearcut (1–6 years) nor litter depth had much influence on mean catches and mean number of species of ants/trap/week.

In laboratory tests conducted under simulated stream conditions treatment with the insect growth regulator diflubenzuron at 1.0 mg/L/30 min at 15°C resulted in 100% mortality of Simulium larvae after 10 days. At 0.5 mg/L/15 min there was 97.6% mortality of S. vittatum larvae after 18 days in water at 10.5°C. Diflubenzuron was less effective when the growth rate of simuliid larvae during the test was slow due to inadequate nutrition, and it was more effective at 25 than at 20°C, but there was no difference in efficacy between 10 and 20°C. Efficacy against simuliid larvae varied inversely with their instar. Diflubenzuron at 1.0 mg/L/30 min was tested in the laboratory against selected nontarget invertebrates. Among the Ephemeroptera tested at 15°C, Baetis pygmaeus, Leptophlebia sp., and Isonychia sp. proved susceptible but not Stenonema fuscum and Ephemerella subvaria. Similarly diflubenzuron had little effect on the perlid stonefly Paragnetina media at 15°C and on the filter-feeding caddisfly Hydropsyche betteni at 20°C. Chironomid larvae (Phaenopsectra sp.) tested at 20°C were affected and the amphipods Gammarus pseudolimnaeus and Hyalella azteca were particularly susceptible at 25 but not at 15°C.

Because egg production in Tabanus atratus, T. catenatus, T. lineola, T. quinquevittatus, and T. similis is not known in southwestern Quebec, potential fecundity and body size were evaluated respectively from the analysis of ovariole number and wing length in field-collected females. Ovariole number appears to be proportional to the third power of wing length, and fecundity indices can be derived from that relationship. Significant differences in body size and potential fecundity of the species suggest that there are different reproductive strategies within the genus Tabanus. Body size and potential fecundity varied significantly in both sampling years in T. lineola but not in T. quinquevittatus or T. similis. These results may prove useful in future studies of population dynamics or phylogeny.

The obliquebanded leafroller, Choristoneura rosaceana (Harris), is a polyphagous insect that is occasionally a serious pest of apple trees. To determine how well adapted it is to this host plant, we studied its nutritional ecology by measuring the development and mortality of larvae and pupae reared on different sets of leaves. We investigated the influence of 3 apple cultivars, 2 time periods (June, July–August), and several leaf types, including those with different ages and different branch positions, on these processes. Larvae and pupae developed more rapidly with lower mortality on younger leaves than on older ones. When larvae were fed leaves collected from the same cultivar and branch position at different times during the season, developmental rates were faster and survival rates were higher earlier in the season. Development and survival were similar on leaves of all cultivars.

The 9 species of the Lasionycta leucocycla complex are reviewed and the number of species reduced to 4. Populations of these species are arranged in 18 subspecies, of which 3 are described as new: L. leucocycla magadanensis Kononenko and Lafontaine, from Magadanskaya Oblast’, L. staudingeri sajanensis Kononenko, from southern Siberia, and L. quadrilunata yukona Lafontaine, from northwestern Canada. Lasionycta dovrensis (Wocke), of the Palaearctic region, is treated as a subspecies of L. leucocycla. Characters to distinguish the species and subspecies, and their distributions are given. The larva of L. staudingeri is described.

During the course of a census of arthropods in a collard crop (Brassica oleracea var. acephala) (Cruciferae) in central New York State in summer 1985, the authors witnessed frequent incidents of unusual feeding behavior in mirid bugs. In late July and early August, numerous observations were made by three of the authors (TWC, OSN, and BAC) of apparent feeding by nymphal (2nd–4th instar) and adult tarnished plant bugs, Lygus linolaris (Palisot de Beauvois), on cocoons of Apanteles glomeratus (L.), a braconid parasitoid of the imported cabbageworm, Pieris rapae (L.). The predation occurred in a period of unusually high P. rapae population densities (estimated at 150 000 ha−1), when A. glomeratus cocoons were abundant on collard leaves.

Based on a simple graphic analysis, I conclude that blackheaded budworm population density cycles are caused by delayed negative feedback processes, probably due to the numerical response of insect parasitoids. The parasitoid–host interaction, however, has a stable solution and continuous population density cycles can only be maintained in a variable environment.

Microplitis mediator (Haliday) is being considered for introduction into Saskatchewan to augment the biological control of the bertha armyworm, Mamestra configurata Walker. It was reared in the laboratory on larvae of the bertha armyworm. Notes on the life history and descriptions of the egg and three larval stages are given.

Ce texte décrit deux nouvelles fourmis néarctiques appartenant au genre Leptothorax (stricto sensu). La première, L. retractus, occupe un territoire transcontinental, tandis que la deuxième, L. sphagnicolus, fut repérée jusqu’à présent uniquement dans les pessières tourbeuses de la région du Saguenay–Lac St Jean, au Québec. Leur nombre respectif de chromosomes se chiffre à n = 17–18 et n = 13. Toutes deux se distinguent par une production inusitée de formes femelles intermédiaires et une répartition géographique de nature boréo-tempérée. Leurs caractéristiques bio-écologiques connues et leurs relations taxonomiques dans le genre sont discutées.

The Douglas-fir cone moth, Barbara coljaxiana (Kearfott) (Lepidoptera: Tortricidae), has the capacity for prolonged diapause, i.e. diapause for two or more winters (Hedlin 1960). This diapause allows for temporal spacing of populations and reduction of intraspecific competition. Specifically, when cone crops are small, excessive moth densities can occur and cause conelet mortality prior to completion of feeding by cone moth larvae, which results in moth mortality. If all moths emerged each year, moth-caused destruction of the conelet population, particularly in years of light production, would have drastic effects on the moth population.

Tree size and bark surface area infested in trees killed by the western pine beetle (WPB), Dendroctonus brevicomis LeConte, and the density of attacking and emerging WPB were measured on 91 trees spanning five consecutive generations of the insect. The emergence densities of six natural enemies were also estimated.

Trees averaged 50.9 cm in diameter at breast height (DBH) with a mean height to base of infestation (HBI) of 1.1 m. Heights to top of infestation (HTI) averaged 16.0 m, but were significantly lower in trees attacked by the second [70(1)] and third [70(2)] generations, during synthetic pheromone elution, than in the first [69(3)], or fourth [70(3)], and fifth [71(1)] generations, before and after the treatment, respectively. Infested bark area averaged 2005 dm2 per tree for all generations.

WPB attack density declined steadily from 4.36 beetles/dm2 in generation 69(3) to 0.86 beetles/dm2 in 71(1). Sampling errors ranged from 6.67 to 26.27%, higher than the desired 15% in some cases. WPB emergence in field sticky traps (STIK) followed an opposite trend from 1.66 beetles/dm2 in 69(3) to 5.43 beetles/dm2 in 71(1). Sampling errors ranged from 8.39 to 28.26%. WPB emergence in laboratory rearings (REAR) averaged 4.03 beetles/dm2 with no significant differences among the generations. Sampling errors ranged from 8.20 to 28.77%. Because of inconsistent differences between these two methods of measuring WPB emergence, we have reported estimates of both.

Densities of attacking and emerging WPB were found to be uncorrelated with tree diameter, indicating that density was not a function of tree size and that these two variables may be treated as independent random variables when used in product models to estimate area-wide population totals.

Sampling errors for natural enemies were quite large, ranging up to 400%; therefore few conclusions could be drawn. Predators, in descending order of abundance, were Aulonium longum, Medetera aldrichii, Enoclerus lecontei, and Temnochila chlorodia. Parasitoids were less abundant overall than predators, with Roptrocerus xylophagorum more consistently present and at higher average densities than Dinotiscus burkei.

The suppression treatment was applied during the collapse phase of the population cycle and apparently prolonged that phase for two generations. This delay resulted in the death of an additional 120 trees. WPB productivity increased with decreasing density/square decimetre of attacking beetles. Density of attacking beetles appears regulated by exogenous processes acting immediately in an inverse density-dependent manner. The WPB population at Bass Lake would be released from endemic to epidemic status at the equilibrium point reached at a density of attacking adults of loge 1.65 beetles/dm2. Mortality of the developing within-tree life-stages appears regulated by delayed density-dependent processes, but the details of the relationships differ depending upon the assessment method (STIK or REAR) used.

The “new approach” to selecting biological control agents, as proposed by Hokkanen and Pimentel in 1984, through the use of new exploiter–victim associations is inappropriate for the biological control of weeds because of certain misconceptions in their method. Examples of biological control of weeds cited in their analysis were biased towards cactaceous insects, and cacti are not representative of target weeds. Several of their “new” associations were inaccurate. These inaccuracies are discussed and additional examples are provided to refute the proposed method. Contrary to the recommendation of Hokkanen and Pimentel, new exploiter-victim associations offer limited opportunities for biological control of non-cactaceous weeds with insects, and should not be used as the preferred method in selecting biotic agents for the biological control of weeds.

Reemergence of Ips calligraphus (Germar) was studied at nine constant temperatures from 10 to 37.5°C. The relationship of adult residence time to temperature formed a backward "J"-shaped curve. Median residence times ranged from 6.25 days at 30°C to 163.5 days at 10°C. The distributions of residence times changed with temperature and were nearly uniform at the low temperatures, peaked and skewed to the right at the intermediate temperatures, and nearly symmetric at the high temperatures. Greater than 93% of all adults reemerged at temperatures from 12.5 to 35°C but only 56% reemerged at 37.5°C. Female residence time was about 26% longer than the male. A mathematical function of reemergence rates versus constant temperatures and a distribution function of normalized reemergence times predicted percentage reemergence of a population through time. In simulations, a multiple-cohort procedure was applied using frequency distributions of field attacks to identify the starting times of the model. Model predictions compared favorably with reemergence from three trees in each of four field plots.

Carbon dioxide increased by 9-fold on the average the number of Tabanus quinquevittatus Wiedemann females collected in canopy traps without affecting parity rates, prevalence of sperm and fructose, and stage of terminal follicle development within nullipars, pars, or both groups together. Results were consistent whether the 2 years were pooled or considered separately.

A key is given for 29 species in the subgenus Lambersius Olive in America north of Mexico. An annotated list is provided for 22 species, and descriptions for the following 7 new species: Uroleucon (Lambersius) carberriensis n. sp., U. (L.) clydesmithi n. sp., U. (L.) coloradensis n. sp., U. (L.) manitobensis n. sp., U. (L.) nevadensis n. sp., U. (L.) penderum n. sp., and U. (L.) suzannae n. sp. Uroleucon (Lambersius) tissoti (Boudreaux) is declared to be a synonym of U. (L.) luteolum (Williams) and U. (L.) baccharidis (Clarke) as a nomen dubium.

The objective of the present work was to determine the statistical distribution of midge damage between heads of wheat as a guide to estimating the number of wheat heads that would constitute a reliable sample in estimating losses caused by this pest. A brief account of the history and geographical distribution of the wheat midge in Manitoba has been given by Barker (1984).

The relationship between the phenological development of the spruce budmoth (SBM), Zeiraphera canadensis, and that of its primary host, white spruce, was studied in New Brunswick using descriptive indices for both insect and host development. Larval emergence of SBM was synchronized with bud burst of white spruce, the species on which most eggs are laid. Subsequent SBM larval development can be estimated through reference to the development index for white spruce. For black, Norway, and red spruce, initial bud burst occurred approximately 15, 3, and 15 days, respectively, later than white spruce and this asynchrony is probably one of the reasons why the SBM is not an important pest on these tree species.

Red Delicious and Winesap apples infested with San Jose scale were placed into either regular (CS) or controlled-atmosphere (CA) cold storage, either with or without prior fumigation with methyl bromide. Fumigation with a dose of 32 g/m3 killed all infesting stages of the scale on Red Delicious apples in CS after 31 days and in CA after 137 days. Complete scale mortality on Winesap apples occurred after 167 days in CA and in CS if previously fumigated.