Long term daily feeding in individual adult males and females of Periplaneta americana (L.) was quantified using a standardized diet. There was considerable variation among days, probably related to digestive processes with a period greater than 1 day. Female feeding was correlated with the reproductive cycle, most feeding occurring during the first few days after depositing an oötheca. Females differed with respect to the length of their reproductive cycles, and the amount of food that was accumulated prior to producing an oötheca. Females with high feeding rates produced oöthecae at a faster rate, but they were less efficient at converting food into oöthecal biomass than females that ate more slowly. A decrease in temperature from 25 °C to 20 °C more than doubled the length of the reproductive cycle, but the amount of food accumulated during inter-ovipositional intervals and the size of the oöthecae were not affected.

Under laboratory conditions adult feeding, ovipositional preference, daily fecundity and longevity, as well as larval and pupal development time and survival of the alfalfa blotch leafminer, were compared on Anchor, Vernal, Iroquois, and Saranac varieties of alfalfa. Although some significant differences were noted, no constant trends were evident when considering all parameters, and rmax values for A. frontella (Rondani) on the four varieties tested were very similar.

Data from field plots confirmed that intervarietal differences of the varieties tested were not of sufficient magnitude to markedly affect the population dynamics of this pest species.

Female stable flies, Stomoxys calcitrans (L.), from larvae reared on the standard CSMA (Chemical Specialties Manufacturing Association) medium required 5 days of blood feeding before producing their first batch of eggs. When the larval medium was supplemented with 1 or 2% cholesterol, resultant females were able to produce mature eggs after only 4 days of blood feeding. Females from larvae reared on the 2% cholesterol-supplemented medium had slight but significant precocious follicular growth at the time of emergence from the puparium. When blood feeding was restricted, the size at which follicular growth ceased was consistently higher in females fed the cholesterol-supplemented diets as compared with control females.

Egg distribution by the solitary parasitoid Aphidius nigripes was studied experimentally at 14 densities of the host aphid, Macrosiphum euphorbiae. The number of hosts parasitized increased with host density, the functional response being of Holling's type II. However the average number of eggs/female was not significantly affected by host density, and consequently superparasitism increased with decreasing host density. When egg distributions were tested against random models, higher than predicted numbers of both unparasitized and superparasitized hosts were observed at all densities tested. Further analysis assuming random search suggested that female A. nigripes tend to deposit several eggs per host while experiencing a low rate of encounter with hosts. The ecological significance of this behaviour is examined.

Brown larval morphs, diagnostic of Choristoneura occidentalis Freeman, and green larval morphs, diagnostic of C. retiniana (Walsingham), were found on both Douglas-fir and white fir in mixed stands in south-central Oregon. The rank proportion of brown morphs in stands was strongly correlated with the rank proportion of Douglas-fir in host species basal area component. Despite considerable overlap in most phenotypic characters, differences in phenotypic frequencies between sympatric green and brown morphs were found in larval head capsule pigmentation, thoracic shield pigmentation, pupal coloration, and adult forewing ground color. In laboratory matings, neither larval host nor larval color morph influenced the mating success, as assessed by the production of viable eggs. Crosses between females reared from brown larval morphs and males from green morphs produced a slightly lower proportion of viable eggs when compared with intramorph matings. Larval host had little effect on either the fecundity of females or the viability of their progeny. Females reared from brown larval morphs produced significantly more eggs than their green counterparts from the same stand. The occurrence of intermediates in all mixed stands and the production of families with anomalous morph frequencies indicate that these two species hybridize in nature. The lack of much structural differentiation and varying efficacy of reproductive barriers indicate that relatively little differentiation of the regulatory genome has occurred between these two species.

The pheromone specificity of female Choristoneura occcidentalis Freeman and C. retiniana (Walsingham) from several locales, laboratory colonies, and interspecific matings was determined by observing the numbers and wing maculations of males attracted at several sites in southern Oregon. Pheromone specificity of females reared from field-collected brown (typical of C. occidentalis) and green (typical of C. retiniana) larval morphs differed considerably but differed little among sites of origin. Field-collected females attracted more males than conspecific individuals from laboratory colonies. F1 and F2 interspecific hybrids most closely resembled C. occidentalis in the numbers and types of males attracted. As a group, progeny of backcrosses to C. retiniana appeared intermediate between pure lines of the species in their pheromone specificity. Females reared from intermediate-colored field-collected larvae varied considerably in attractiveness. Most attracted groups of males similar to those attracted to female C. retiniana, but others attracted males most similar to those attracted to female progeny of C. retiniana hybrid backcrosses. These findings support the conclusion that hybrid matings occur between these species at a low frequency in nature.

Two subspecies, Troides amphrysus chrysomelas new subspecies and T. helena bunguranensis Ohya, from Natuna islands, Indonesia are described.

Two new species of Aphis L. are described, holodisci from British Columbia and Oregon, and schuhi from Oregon, both from Holodiscus discolor Maxim.

Spatial segregation between the colonial homopterans Aphis vernoniae Thomas and Publilia reticulata Van Duzee on New York ironweed, Vernonia noveboracensis L., does not occur either among plant patches or among plants. Before August, spatial separation occurs on the plants, with A. vernoniae concentrated in the inflorescences and P. reticulata concentrated on the middle leaves. Apparent overlap increases as A. vernoniae moves onto senescing leaves late in the season. However, the A. vernoniae colonies are found nearer to the petiole, and there is little actual overlap in the distributions of the two species.

Maris Kestrel kale, Brassica oleracea L., was planted and sampled in two locations during 1977–78. The aphids Brevicoryne brassicae (L.) and Myzus persicae (Sulzer), syrphids in the genera Syrphus and Scaeva, the cecidomyiid Aphidoletes aphidimyza (Rond.), the parasite Diaeretiella rapae (M'Intosh), and the fungus Entomophthora aphidis Hoffman were observed in the samples. A volumetric technique for assessing aphid numbers was developed and evaluated. Peak numbers of B. brassicae differed by an order of magnitude between plots, but the pattern of monotonic increase in the spring, followed by an abrupt decline in the rate of increase, a mid-summer peak, and an autumn population decline was consistent throughout. The first major decline in the rate of increase of B. brassicae was correlated with the appearance of A. aphidimyza and syrphid larvae. Declining adult aphid weight, which suggested declining fecundity, increased alate production at high aphid densities, parasite pressure, and leaf fall added to the damping effect of predators. In autumn, cool temperatures and production of sexuals further reduced the rate of increase of B. brassicae.

Developmental time of Brevicoryne brassicae (L.) was measured in the laboratory at 8°, 13°, 18°, and 23 °C. Time from birth to adult was 126 degree-days above a threshold of 6.7 °C (°D6.7). Age-specific fecundity and longevity was measured at 13°, 18°, and 23 °C. The temperature thresholds for birth and physiological death rates were not significantly different from 6.7 °C. Fecundity averaged 40.7 nymphs/female and did not vary with temperature or frequency of removal of nymphs. Peak reproduction occurred 75°D6.7 after the molt to adult. Although the time of peak reproduction did not vary as a function of fecundity, height of the reproductive peak and length of the reproductive period did, but not in a 1:1 proportion. Age-specific fecundity was described as a polynomial function of aphid age in °D6.7 and fecundity. Longevity did not vary as a function of fecundity. All aphids survived until after the reproductive peak, so the sum of the age-specific fecundities very nearly equaled the net reproductive rate. Measurements of developmental time, fecundity, and longevity of B. brassicae in the field were 1.3, 0.66, and 1.2 times the respective laboratory value. Consecutive measurements of developmental time and fecundity showed that the former increased and the latter decreased during the season. The consequences of variable developmental time, fecundity, and age-specific reproductive pattern to the quantitative representation of population growth rates are discussed.

Developmental time, fecundity, adult weight, numbers, and age distribution of Brevicoryne brassicae (L.) and leaf area and plant quality of Maris Kestrel kale, Brassica oleracea L., were determined at three aphid densities and two watering rates in a factorial field-cage experiment. The watering treatment had no effect on the aphid or plant response variates. The aphid density treatment significantly affected final aphid numbers (low < medium = high density), leaf area (high < low = medium density), average adult weight measured at the end of the experiment (high < low < medium density), and weight of the adults in the developmental time measurement (high < low = medium density). The results suggested a strong aphid–plant interaction, but at densities which rarely occur in the field. Leaf water/dry weight was used to assess plant quality, but it was not a good predictor of any of the aphid response variates. Developmental time decreased, and fecundity increased as adult aphid weight increased. Production of fourth-instar apterae decreased logarithmically as aphid density increased.

Predation of the cabbage aphid, Brevicoryne brassicae (L.), by the cecidomyiid Aphidoletes aphidimyza (Rond.) was studied in the laboratory and the field. Predation was random with respect to aphid instar, and predation rate was constant with respect to aphid density. A. aphidimyza consumed 1.7 times more aphids in the laboratory than in the field during larval development. When aphid weight and age distribution were accounted for, it was found that the same biomass, 2.14 mg, was eaten in both cases.

The pupal developmental temperature threshold for A. aphidimyza was 9.2 °C. The developmental times of the egg, larval and pupal stages, and complete life cycle were 32°, 66°, 171°, and 283°D9.2. In the field, there was at least 5 times more food available on individual leaves than was necessary for larval development, suggesting that female A. aphidimyza took care to place their eggs where there was sufficient food for larval development.

The numerical response of A. aphidimyza to aphid density was calculated using sample data from three field plots. The response between plots was not statistically different.

The implications of using prey weight rather than number to measure predator consumption, and biological control of aphids by A. aphidimyza, are discussed.

A computer model was written to simulate the population dynamics of the cabbage aphid, Brevicoryne brassicae (L.), on the host Maris Kestrel kale, Brassica oleracea L., at Vancouver, British Columbia. The model incorporated the effects of temperature, morph determination, plant quality, predators, parasites, and leaf fall. Comparisons of simulated results with field observations indicated that although B. brassicae, Aphidoletes aphidimyza (Rond.), and Diaeretiella rapae (M'Intosh) were reasonably well understood, syrphid predation was not, and appropriate feed-back mechanisms which could prevent monotonic increase or decrease in the simulated population were lacking. A detailed study in which the population dynamics of the prey is accounted for in terms of the numerical and functional responses of syrphid predators is necessary to understand the population dynamics of B. brassicae on Maris Kestrel kale at Vancouver. Comparisons with other aphid systems suggest that a major change in one component of the system can be compensated for by changes in other components. An overview of the cabbage aphid system at Vancouver is given.