The first of a planned series of papers revising the Nearctic species of the predaceous diving beetle genus, Agabus Leach, is presented. The genus is defined in the broad sense of Sharp (1882) and Fall (1922). The North American species are divided into species groups and diagnostic characters for group recognition are summarized in a key. Assignment of species to these groups is indicated in a checklist of North American species. The ambiguus-, tristis-, and arcticus-groups are defined, their relationships discussed, and included species revised. The ambiguus-group, which is restricted to North America, contains the species A. ambiguus (Say), A. strigulosis (Crotch), A. erythropterus (Say), A. austinii Sharp, and A. klamathensis sp.nov. The tristis-group, which has a Holarctic distribution, contains two species in North America, A. tristis Aubé and A. leptapsis (LeConte). The Holarctic arcticus-group is represented by A. arcticus (Paykull) and A. anthracinus (Mannerheim) in North America. For each species, patterns of variation are described, the North American distributions mapped, and ecological information summarized.

The relative diapause intensity of a French univoltine and Saskatchewan commercial strain of the alfalfa leafcutting bee, Megachile rotundata (Fab.), was evaluated over a 3-year period. Prepupae from both strains underwent diapause development at 10 °C for different time periods. Diapause intensity was estimated by scoring days to emergence after initiating incubation at three different times in each of the 3 years: fall incubation (immediate post harvest); winter incubation; and spring incubation. In all comparisons made, the univoltine strain had a significantly increased diapause intensity compared with the commercial strain. We concluded that diapause intensity was heritable and that this stable difference between strains could provide the basis for a selected line with increased univoltinism under field conditions.

Larvae, deutonymphs, and male and female adults of Platyhydracarus juliani sp.nov., and adults of P. parvipalpis sp.nov., are described from rheocrenes and small streams in western North America. The genus Platyhydracarus gen.nov. is proposed and diagnosed, based primarily upon the presence of genital acetabula both in the gonopore and on acetabular plates flanking the gonopore, and of a group of thickened setae anterior to the gonopore, in male adults. Possible relationships between Platyhydracarus and other Athienemanniidae are discussed, and a new key to the genera of Athienemanniinae is presented.

The North American species of Momonia Halbert, 1906, are revised. Larvae, deutonymphs, and adults of Momonia campylotibia sp.nov. are described, adults of Momonia marciae Habeeb and Momonia projecta Cook are redescribed, and deutonymphs of M. projecta are described for the first time. New morphological, life history, and distributional data are presented for all species. A new diagnosis of Momonia is proposed, and a key to adults of all known species of the genus is included.

Morphological, life history, and distributional data are presented for North American species of the subgenus Allomomonia Cook, 1968. Adults of Stygomomonia (Allomomonia) moodyi Mitchell are redescribed, and deutonymphs and adults of four new species, S. (A.) pacifica, S. (A.) mendocinoensis, S. (A.) mitchelli, and S. (A.) atnarkicola, are described for the first time. Larvae tentatively identified as S. (A.) mitchelli are also described, and host associations of these, and larvae that appear to belong to other species of Stygomomonia, are presented and discussed. New distributional data are presented for all species. A new diagnosis of Allomomonia is proposed, two new species groups, the moodyi and mitchelli groups, are proposed and diagnosed, and a key to adults of North American species of the subgenus is included.

Geina sheppardi sp.nov., a grape-feeding platyptiliine (Pterophoridae), is described. Its distribution, biology, and diagnostic features are discussed and related to those of two other partly sympatric and morphologically similar species of grape-feeding Platyptiliinae, Sphenarches Ontario (McDunnough) and Geina periscelidactyla (Fitch). A lectotype is designated for the latter.

The effects of fenoxycarb, ethyl[2-(p-phenoxyphenoxy)-ethyl]carbamate, an insect growth regulator with juvenile hormone activity, on reproduction in Ips paraconfusus Lanier were investigated. Topical treatment of either females or both sexes of parent beetles with 50 μg of fenoxycarb per insect resulted in a significant reduction in hatching of eggs and numbers of progeny produced by beetles allowed to infest logs of ponderosa pine, Pinus ponderosa Laws. When pairs of beetles were allowed to attack logs that were surface-treated with fenoxycarb, the effects on reproduction at a dose of 100 μg/cm2 of bark surface were comparable to those of a topical treatment at a dose of 50 μg per insect. However, at doses of 1000 or 10 000 μg/cm2 the adverse effects included reductions in the length of egg galleries, fecundity (number of egg niches), and number of freshly laid eggs. Percentage reductions in progeny were 35.8, 82.5, and 95.7 for doses of 100, 1000, and 10 000 μg/cm2, respectively, if brood beetles were allowed to emerge from the logs. This study indicates that fenoxycarb acts as an effective chemosterilant on I. paraconfusus.

The first record of Dipalta serpentina Osten Sacken, 1877, preying on larvae of Myrmeleon immaculatus DeGeer, 1773, was by Smith (1934: 136-137), who stated that the fly larvae were “parasitic” on the antlion larvae. Cole and Schlinger (1969: 251) stated that the fly larva of this species “…is parasitic on the larvae of Myrmeleontidae.”

Although the fly larvae may prey upon the larvae of the antlion, we have established that they definitely prey upon the antlion pupae (Fig. 1). Judging from the emergence dates (early September 1988) of the flies, each had preyed upon an antlion pupa within its cocoon. Each antlion cocoon had one hole in it. An examination of the contents of each antlion cocoon revealed the cast skin of the antlion larva and the empty, clear skin of the antlion pupa. The pupal skins were not split open, which they would have been if the adult antlion had emerged. They were shrivelled, and looked much as if the contents had been sucked out.

Patterns of seasonal abundance of Colorado potato beetle, Leptinotarsa decemlineata (Say), potato flea beetle, Epitrix cucumeris (Harris), potato leafhopper, Empoasca fabae (Harris), and aphids on potato cv. Norland are reported for the 1983–1985 growing seasons in southern Manitoba. Each year, Colorado potato beetles and potato flea beetles underwent one generation on the crop. There were two peaks of leafhopper abundance in 1983 and 1984, but only one was evident in 1985. Aphid populations rose to a single peak in August of each year.

In experimental plots in the absence of insecticides, Colorado potato beetles completely defoliated plants in two seasons out of the three. In commercial fields, insecticide sprays applied in July and early August greatly reduced populations of Colorado potato beetles for the rest of the season, and there was no defoliation at harvest. Insecticides had less effect on potato flea beetle populations. Leafhopper and aphid populations were small at the time of spraying.

In 1986 a greenhouse population of Liriomyza trifolii (Burgess) was shown to be highly resistant (155-fold at LC50) to the organophosphorus compound pyrazophos. However in 1987, the same population had only 35–40% resistant individuals remaining. A survey in 1986 of five other greenhouses reporting leafminer control failures indicated three other resistant populations in southern Ontario. Resistance was not affected by the addition of the synergists diethyl maleate or triphenyl phosphate to pyrazophos. Cross-resistance to the phosphorothioate insecticides demeton, chlorpyrifos, and triazophos was indicated.

The species of Limnozetes of northeastern North America are treated. A new generic diagnosis is given. Eight new species are described: L. latilamellata, L. guyi, L. borealis, L. onondaga, L. amnicus, and L. palmerae on the basis of adults and immatures, and L. lustrum and L. atmetos on the basis of adults. Identification of adults and immatures of these species is presented in tabular format. The range of morphological variation exhibited by these species is discussed. Transformation series for eight character states in Limnozetes are hypothesized on the basis of comparison with Hydrozetes. A key is given to the adults of the nine species of Limnozetes recorded from northeastern North America.

A study was conducted to examine the relationship between development rate and constant temperatures (14, 21, 24, 27, 33, 36, 40, and 45°C) for the rangeland grasshoppers Melanoplus sanguinipes (F.) and Aulocara elliotti (Thomas). Non-linear regression was used to generate estimates of lower development thresholds. The chosen model provided for a concave-shaped development rate function at temperatures above the lower threshold and required fewer parameters than previous models. Although experimental results suggested that no precise estimates of upper development thresholds could be obtained, previous field studies indicate that preferred body temperatures may be lower than ambient temperatures and probably are related in part to the thermoregulatory abilities of the two species studied. Results will be of interest to insect ecologists and those studying grasshopper biology as well as researchers and pest managers interested in predicting grasshopper development.

Phenology, fecundity, development, and mortality were studied for co-occurring, declining populations of Dendroctonus ponderosae Hopkins in limber pine and lodgepole pine at two sites in the Porcupine Hills of southwestern Alberta in 1985–1986. Beetles reared in lodgepole pine emerged and attacked new hosts 7–8 days earlier than those in limber pine in 1985. Beetles were able to utilize over two-thirds of the length of each limber pine bole but only about one-third of the length of each lodgepole pine bole. Also, beetles infesting limber pine had significantly higher fecundity, produced more eggs per centimetre of gallery length, and their progeny developed faster and survived better than beetles infesting lodgepole pine. There was no apparent phenological or other barrier that might inhibit gene flow between D. ponderosae populations in limber pine and lodgepole pine. In the area studied, limber pine was a better host for D. ponderosae reproduction, development, and survival than was lodgepole pine. Thus, beetle populations may be able to increase much more quickly in limber pine, arguing for regular monitoring of these populations.

The incidence of diapause in pupae of the second (overwintering) generation of the carrot rust fly, Psila rosae (Fab.), at the Holland Marsh, Ont., was determined at intervals during fall and spring of 1982–1983, 1984–1985, and 1985–1986, by placing pupae collected from carrot plantings at developmental temperatures in the laboratory. The percentage of samples in diapause increased with time of sampling from late September on, until 100% of the pupae collected in late November or early December were in diapause. The percentage in diapause of pupae overwintering in the ground of an insectary at Jordan Station, Ont., decreased from January onward until, by early April, diapause was virtually absent. In spring collections from the Holland Marsh, some evidence of diapause was detected in the earliest samples, indicating that diapause is a factor that should be considered when degree-day models are being developed for the carrot rust fly.

The sex pheromone components of the black army cutworm, Actebia fennica (Tauscher), were identified in abdomen-tip extracts from calling female moths. The primary pheromone component was (Z)-7-dodecenyl acetate. Although (Z)-11-tetradecenyl acetate was detectable only in trace quantities in the extracts, it was the major component in the best synthetic blend for attraction of male moths. The most effective synthetic blend was (Z)-7-dodecenyl acetate and (Z)-11-tetradecenyl acetate at a ratio of 1:20. No other component detected in the extracts increased trap capture of males when added to the two-component blend; however, (Z)-5-dodecenyl acetate, (Z)-7-dodecenol, and (Z)-9-tetradecenyl acetate reduced catches. This two-component blend will be useful for studying the habits of the adults and for population monitoring.

A phenology model for jack pine budworm, Choristoneura pinus pinus Freeman, is presented. Linear and nonlinear relationships between temperature and the development of overwintering larvae, instars 2–7, and pupae are determined, as is variation in the development of each instar. The model uses as input daily maximum and minimum temperatures corrected for the effects of bark and bud microclimate and simulates the number of insects in each instar on a given calendar date. Variation in development of all stages is included. Simulations matched observed data well for north-central and northwestern Ontario in 1986, but overestimated time of development for northwestern Ontario in 1987. Simulations under low, medium, and high temperature conditions revealed that a nonlinear equation for rate of development was necessary for simulating emergence whereas linear rate equations were adequate for simulating development of the feeding instars. The combined effect of bud and bark microclimate on model performance was equal to that which resulted from the use of nonlinear developmental equations.

Predation of gypsy moth larvae, Lymantria dispar L. (Lepidoptera: Lymantriidae), by ants was observed by placing caterpillars on the forest floor and waiting for ants to find them or by placing caterpillars very close to foraging ants. Over 80% of contacts with caterpillars were made by Formica spp. The rate of successful capture varied with caterpillar instar, generally becoming lower as larvae became larger. However, neonates were successfully attacked by ants less often than first-instar larvae that had fed. Neonates probably have developed defenses that prevent excessive predation because many fall to the forest floor when dispersing. The distribution of time intervals between encounters of ants with larvae was adequately fit by an exponential distribution having a mean waiting time of 20 min. This distribution was used to construct a simulation model of gypsy moth larval predation by ants. Based on the model results, ant success rate, ant foraging density, and residence time of larvae on the forest floor were important determinants of mortality caused by ants.

The 45-cm mid-crown branch tip from balsam fir and white spruce is described in terms of surface area, fresh weight, and bud density. Fresh weight is suggested as the most appropriate unit to express density of all stages of the spruce budworm’s, Choristoneura fumiferana (Clem.), life cycle, particularly for the purposes of comparisons between host species and locations with different foliage conditions.

Changes in distribution of the spruce budworm in the crown of balsam fir are documented for all stages of the insect’s life cycle. Correction factors to account for these changes when estimating density on the basis of the 45-cm branch tip sampling unit are given for balsam fir and white spruce.

The amount of error in detection of spruce budworm larvae on foliage of both host trees by sampling personnel varied systematically and consistently as a function of insect development. A method to compensate for this type of error is also suggested.

Adults of Scapuleremaeus kobauensis gen.nov., sp.nov. are described from British Columbia. The systematic relationship of this genus to other genera in the Cymbaeremaeidae is discussed.