Spruce beetles (D. rufipennis) from a population homogeneous with respect to population quality were subjected to different degrees of competition at corresponding stages of their reproductive cycles by varying the spacing of individuals and by varying the time of introduction of individuals into the competitive environment. Competition effects increase with gallery accumulation, as suggested in previous studies, and result in subsequent reduction of gallery production and oviposition. Increase in individual beetle quality, however, confers increased powers of resistance to the competition effects. Initial egg-free length is an unsuitable attribute for comparisons of populations. Expression of reproductive efficiency is a dynamic population characteristic which varies over the reproductive cycle, and which may be readily estimated by measurement of yolk deposition rate. For comparing populations, such measurements would be more valuable when carried out before the onset of competition effects. Individuals with the highest quality at the start of the egg-production cycle exhibit the highest reproductive efficiency as conditions change.

The green lacewing, Chrysopiella brevisetosa n. sp., occurs in the northwestern United States and Alberta, Canada. The description includes figures comparing head and terminalia of this species with those of C. pallida

Ceutorhynchus litura (F.) (Coleoptera: Curculionidae) is established since 1967 in Ontario, and is increasing slowly on nine release sites in five provinces. The weevil is not a good control agent because its reproductive capacity does not compensate for losses inflicted by cultivation and the stress resulting from larval mining is so light that it produces no noticeable reduction in the vigour of Canada thistle (Cirsium arvense (L.) Scop.). In contrast to earlier findings, it is doubtful that C. litura aids in the spread of the rust Puccinia punctiformis (Str.) Rohl. Further stress factors from other insects or pathogens are needed to control this vigorous weed.

The last instar larva of Hellula rogatalis (Hulst) is described and illustrated. Diagnostic characters of the genus are given, and a key included for the North American species. Larvae of this genus are compared with those of Dicymolomia Zeller.

The structure of the sclerous parts of representative Rhynchota is analyzed and compared with those of Psocoptera and Thysanoptera. Known data on embryology and musculature are also considered in deriving homologies of the structures. The term "suture" is redefined. Standardized terms for the sclerous parts of the head capsules of Rhynchota are recommended and compared with those of previous authors. A phylogenetic synthesis is presented, demonstrating the evolution of the homopterous head capsule through intermediate stages represented in the modern fauna by Psocoptera, Thysanoptera, and Hemiptera–Gymnocerata. Evidence is presented that Coleorrhyncha are related to Hemiptera rather than to Homoptera, that the Gymnocerata and Cryptocerata are natural groups within the Hemiptera and that Cicadomorpha, Aphidomorpha, and Fulgoromorpha are natural groups within the Homoptera.

Ancylis discigerana (Walker) is a univoltine leaf folder of yellow birch. Final instar larvae overwinter in litter and pupate from mid-April through mid-May. Adults emerge in early June and deposit single eggs on the upper surface of a leaf, usually on a major leaf vein or other small depression in the epidermis. The first two instars skeletonize the lower surface of a leaf, beneath a sheet of silk that is constructed between two lateral veins. Third-instar larvae move to the upper surface of a different leaf and fold it lengthwise. Larvae feed on the upper epidermis within the fold until leaf-fall. Life stages are described.

An egg parasitoid, Trichogramma minutum Riley, and a larval parasitoid, Apanteles polychrosidis Viereck, were the major natural enemies in the population studied.

A key is presented for three species of Ancylis found on yellow birch.

The effect of temperature on development of the carrot rust fly, Psila rosae (F.), was determined at constant temperatures in the laboratory. The relationship between rate of development and temperature was essentially linear from 10° to 17.5°C but began to diverge from linearity between 17.5° and 20°C. Estimated threshold temperatures (t) and thermal constants (K) for development of overwintered pupae were 2.3°C and 319 degree-days (dd) for first emergence and 1.8°C and 368 dd for 50% emergence. For laboratory-reared stages, t and K values were 4.1°C and 102 dd for egg hatch, 2.0°C and 642 dd for development from egg to mature larvae, and 3.0°C and 107 dd for pupation. Development in the laboratory from egg (less than 24 h old) to adult was completed in 59, 70, and 81 days at 20°, 17.5°, and 15°C respectively; no threshold or thermal constant was estimated because few or no individuals completed development to adult at 12.5° or 10°C within expected times, presumably because diapause was induced at these temperatures.

Morgea freidbergi new species, a living sister-species of the fossil species M. mcalpinei Hennig from Baltic amber (Oligocene), is described and compared with its fossil counterpart. Additional characters are given for Morgea Hennig and its placement in Pallopteridae rather than Lonchaeidae is confirmed. A key to the world genera of Pallopteridae is presented for the first time.

In the paper wasp, Polistes metricus Say, subordinates and single foundresses of early colonies (< 16 days old) nesting in the same habitat were very similar in size, reproductive condition, and probability of being fertilized suggesting that these types of foundresses are comparable in reproductive potential. Queens of multiple foundress, early colonies were significantly larger, had larger ovaries, and more oocytes than their subordinates. In late colonies (> 30 days old) the differences in reproductive condition between queens and their subordinates were more pronounced. Reproductive condition and body size are likely to be important characters for sorting foundresses into hierarchies.

A collection of 70 Medicago introductions were field tested for resistance against potato leafhopper, Empoasca fabae (Harris), damage. All M. sativa L. ssp. sativa and most ssp. mixtures were susceptible. All ssp. falcata (L.) Arcangeli, one ssp. mixture sativa and caerulea (Lessing ex Ledebour) Schmalhausen, ssp. × varia (Martyn) Arcangeli and M. pironae Vis were resistant receiving one-half or less damage than the standard cultivars during four seasons of testing. Resistant introductions were slower in regrowth, attained less height, had smaller leaflets, thinner, tougher stems, and more prostrate growth than standard cultivars. Results suggest most observed resistance is due to avoidance of tough stems for oviposition.

Tetracyclos boreios Kryger is redescribed and illustrated, and its placement within the family Encyrtidae (Chalcidoidea) confirmed. The peculiar mechanism of movement of thoracic sclerites is described; this is compared with that of other Encyrtidae and Eupelmidae (Chalcidoidea), and its possible biological significance is discussed.

Similar percentages of parasitized adults and of females of Phyllotreta cruciferae (Goeze) were collected in traps baited with allyl isothiocyanate and in a D-Vac vacuum insect net early in spring and in August–September, when non-reproducing adults predominated. In contrast, a lower percentage of parasitized adults and a higher percentage of females were collected in the traps than in the D-Vac during the beetles’ reproductive period, May–July. A similar difference between the traps and D-Vac was recorded for Phyllotreta striolata (F.) during April–May, when this species begins to reproduce. Therefore, the results indicate that traps used in this study are unsuitable for measuring parasitism and sex ratio of reproducing P. cruciferae and P. striolata.

The last instar larvae of the tribe Pyraustini of America north of Mexico are described. Thirty-five species and 19 genera are included in this study, Munroeodes Amsel—1 species, Saucrobotys Munroe—1 species, Epicorsia Hübner—1 species, Oenobotys Munroe—1 species, Crocidophora Lederer—1 species, Ostrinia Hübner—3 species, Fumibotys Munroe—1 species, Eurrhypara Hübner—1 species, Phlyctaenia Hübner—1 species, Nealgedonia Munroe—1 species, Mutuuraia Munroe—1 species, Anania Hübner—1 species, Hahncappsia Munroe—5 species, Achyra Guenée—2 species, Helvibotys Munroe—1 species, Sitochroa Hübner—1 species, Uresiphita Hübner—1 species, Loxostege Hübner—5 species, and Pyrausta Schrank—6 species. The last instar larvae of 10 species are described for the first time, Munroeodes thalesalis (Walker), Oenobotys vinotinctalis (Hampson), Crocidophora pustuliferalis Lederer, Nealgedonia extricalis (Guenée), Pyrausta dapalis (Grote), P. fodinalis (Lederer), P. sp. near laticlavia (Grote and Robinson), P. orphisalis Walker, P. tyralis (Guenée), P. unifascialis (Packard). The relationships between the adults and the larvae are discussed. Key to the genera for last instar larvae is given, and the larval characters illustrated.

At least two species of Trichogramma (Hymenoptera: Trichogrammatidae) parasitize the eggs of Sepedon fuscipennis Loew (Diptera: Sciomyzidae) in freshwater habitats of central New York. Trichogramma julianoi Platner and Oatman parasitizes S. fuscipennis and Elgiva sundewalli Fries (Diptera: Sciomyzidae). Trichogramma sp. near californicum Nagaraja and Nagarkatti parasitizes S. fuscipennis, E. sundewalli, Tetanocera spp. (Diptera: Sciomyzidae), and pyralid moths (Lepidoptera: Pyralidae). T. julianoi was most active in early and late summer. T. sp. near californicum was most active in mid- and late summer. Another undescribed species, similar to Trichogramma semblidis (Aurivillius), occurs in the same habitats but does not parasitize S. fuscipennis. Its primary hosts are Stratiomyidae (Diptera). Mortality of S. fuscipennis eggs due to Trichogramma varied significantly over the summer and reached 43.6% in late July and early August. A list of parasitoids reared from eggs of insects collected in fresh-water habitats is given.

Four sampling methods for Ooencyrtus kuvanae (Howard) populations were compared for efficiency using coefficients of variation. On this basis, none of the sampling methods was uniformly superior to any other, but a cluster of 0.01 ha subplots was chosen as the best method because of the aggregation of both gypsy moth egg masses and parasitoids. From the estimated population variance per egg mass it was calculated that 150 egg masses should be sampled per plot to provide an error bound of 0.2 parasitoid per egg mass (α = 0.1). An analysis of variance indicated that variation among study areas was the largest source of variation, and that among day, within day, and plot configuration variation were significant. Estimates of parasitoid activity are most reliable during the period between 1300 and 1600 h EST. Activity of parasitoids was reduced on overcast days. In August, the distribution of O. kuvanae approximates that of the negative binomial but with too many individuals in the high frequency classes. In a compromise between cost and accuracy, the sampling scheme selected consists of thirty 0.01 ha subplots per plot sampled between 1300 and 1600 h EST on sunny days. This sampling scheme was found satisfactory using field evaluation.

Laboratory studies showed that elm leaf beetle, Pyrrhalta luteola (Müller), larvae and pupae were susceptible to the nematode Neoaplectana carpocapsae Weiser; adults were less likely to be infected because of their dispersal ability. Spruce budworm, Choristoneura occidentalis Freeman, larvae were susceptible to the nematode in the laboratory. Field application of the nematode in 2% aqueous Volck oil suspension against elm leaf beetle or spruce budworm larvae did not significantly reduce the populations when compared with controls. Desiccation of the infective nematodes may be a factor in the variable results for elm leaf beetle, and cool temperatures and rain may have been factors in the poor results for spruce budworm. However, significant population reduction occurred in nematode treatments against elm leaf beetle pupae in litter. This nematode may be used against beetle pupae in conjunction with other control tactics.

Frazer and Gilbert (1976) described the predation of pea aphids, Acyrthosiphon pisum (Harris), by adult coccinellids. They developed a formula to predict the predation rate as a function of temperature, predator density, and prey age-distribution and density. Gutierrez et al. (1979) extended the formula to describe several predators sharing the same prey. The following papers develop the study to cover the complete predator-prey relationship, including the dynamics of both predators and prey.

Precipitin test techniques were utilized for the identification of predators on three lepidopteran pests—Anticarsia gemmatalis Hübner, Heliothis zea (Boddie), and Pseudoplusia includens (Walker). The test was sensitive enough to detect these prey in a whole-body extract of one small predator or from a midgut extract of larger predators. Some cross-reactivity among the prey antigens was found which limited somewhat the applicability of the test. However, test results from field-collected predators indicated the precipitin test is a simple and rapid technique which can be used to evaluate the number of encounters between predators and prey in soybean fields.

Four species of each of the genera Chrysops, Hybomitra, and Tabanus were collected while feeding on cattle in southwestern Quebec; T. quinquevittatus accounted for 75% of the tabanids. The more abundant species had a flight period of at least 5 weeks. Nearly 90% of the specimens were positive for fructose as determined by the cold anthrone test.

One hundred and ten species of insects together with unidentified spiders and pseudoscorpions were collected in foliage samples of Pinus radiata taken from the three natural mainland populations and two planted populations in California. The diversity of the arthropod community in the crowns of P. radiata D.Don was low with 76% of the total number of individuals accounted for by five species groups and 88% by 11 species groups. Spiders were the most abundant species group, comprising 33% of the total number of individuals. The most abundant insect groups were Homoptera, Hemiptera and Coleoptera, respectively. The natural stands supported more species at higher population levels than the planted stands which supported only two species at very high population levels and the rest at low levels. The arthropod communities at the borders of the natural stands were more diverse than at the centers of the stands. The degree of similarity between the natural stands seemed to reflect their geographic distribution; Ano Nuevo and Monterey were most alike and the differences between Ano Nuevo and Cambria were greater than those between Monterey and Cambria. Differences in insect communities within and between the natural and planted stands are discussed in detail.