The percentage encapsulation of its common insect parasites by Hyphantria cunea Drury was measured in natural populations in New Brunswick and Nova Scotia over a period of 17 years, and the variables affecting encapsulation were studied in laboratory experiments. Percentage encapsulation varied with the species, stage, and activity of the parasite, and the stage and genetic strain of the host. Differences in encapsulation from area to area and particularly from year to year were closely related to short-term changes in the genetic constitution of the host population resulting from natural selection pressures. The application of these results to biological control and to population modeling is discussed briefly.

Four of the parasite species attacking Hyphantria cunea Drury spin their cocoons inside the colonial web of the host, where they are exposed to attack by five species of hyperparasites. Percentage hyperparasitism was measured over a 15-year period in permanent study areas in New Brunswick and Nova Scotia. The mean percentage was about 50%, with very wide variations from year to year. These variations were not related to the population density of H. cunea or its parasites and no model for hyperparasite-parasite interaction could be constructed.

A new species, Limonius pappi, is decribed from specimens from Mono County, California. The pertinent features are illustrated and supplementary couplets to Van Dyke’s (1932) key are provided. A lectotype is designated for Limonius nitidulus Horn.

Conotrachelus neomexicanus Fall occurs throughout the range of Pinus ponderosa Laws. in the central and southwestern United States. It is commonly found infesting ponderosa pine cones in north-central Colorado. C. neomexicanus is univoltine. Eggs are laid in second-year cones from May through July. Larvae mine extensively in the cones and drop to the ground for pupation in the soil. Adults emerge from the soil in late summer and early fall, return to the trees to feed on twigs, and presumably hibernate in sheltered locations during the winter A tachinid fly, Myiophasia sp. nr. ruficornis Tns., is an internal parasitoid of weevil larvae.

Life-table study plots were established in southeastern Manitoba to study the population dynamics of the larch sawfly for the 1956 to 1972 generations and to evaluate the impact of two recently introduced parasites.

Abbreviated life tables were used to calculate k-values, expressions of mortality during the different stages due to various factors. Graphical and principal component analyses of the k-values showed that mortality during the cocoon and adult stages (k5) largely determined population trends. None of the factors affecting populations before the introduction of the parasite Olesicampe benefactor Hinz was density-dependent. However, a form of density dependence appeared to exist for O. benefactor and for its hyperparasite Mesochorus dimidiatus Holmgren. The area of discovery for both species decreased rapidly as the density of the female parasites increased.

A simple model confirmed that k5 was largely responsible for determining population trends. A second model utilizing the relationships between areas of discovery and adult female densities for O. benefactor and M. dimidiatus provided reasonable approximations to observed values for numbers of sawfly eggs, and numbers of adults, rates of attack, and attacks per female for both species of parasites.

Twenty sets of 50 pairs of randomly generated values of k5 were used as simulated input in the second model. None of the values for simulated egg populations of the larch sawfly reached outbreak proportions when O. benefactor and M. dimidiatus were present, but most exceeded these levels in their absence. Larch sawfly populations in southeastern Manitoba should be controlled by O. benefactor in the foreseeable future.

A survey in southern Quebec from 1972 to 1974 at 178 sampling sites shown revealed the presence of 30 culicidian species. For 2 of these species (Aedes decticus and C. melanura), their presence represents a geographic extension. The breeding sites of these 2 species have been characterized by the type of vegetation.

Two forms of Hybomitra typhus (Whitney) flying together have been collected from Ontario bogs. The two forms have been clearly segregated by size and colour characters and also by differences in the appearance of esterase isozymes shown by electrophoresis. The combined data indicate that insects recorded as H. typhus comprise more than one species.

The aequalis group of the genus Euxoa Hübner is defined on the basis of the genitalia. The species in the group are: aequalis (Harvey), acornis (Smith) with two subspecies acornis acornis (Smith) and acornis alko (Strecker), conjuncta (Smith), cona (Strecker), and luctuosa new species. Adults and genitalia are illustrated and a synopsis is given for each species. A key to species and subspecies is included.

Aerial photographs of corn fields in southwestern Ontario were photographically enhanced and subsequently computer-analyzed to determine levels of corn aphid infestation. The flight line included 87 fields, 42 of which were infested to varying degrees. The levels of infestation varied from 35.6% to 67.1% determined from five representative fields.

Two new species, Mestocharis nearctica and M. tropicalis (Chalcidoidea: Eulophidae), are described from North America with a key to species and scanning electron microscope photographs. This is the first report of the genus Mestocharis from North America.

Tetracanthella pacifica sp. n. from Coastal British Columbia is described and illustrated. A key to the Nearctic Tetracanthella species is given.

A 3-year study of spatial distribution patterns of insect pests in soybean fields revealed that the Poisson series described the distribution of most species. These species were: green cloverworms, Plathypena scabra (Fabricius); velvetbean caterpillars, Anticarsia gemmatalis Hübner; loopers Trichoplusia ni (Hübner), Pseudoplusia includens (Walker), and Heliothis spp. The Poisson with zeros distribution was second in characterizing the spatial patterns of many of the species. Field counts of Mexican bean beetles, Epilachna varivestis Mulsant, fitted the Neyman’s type A and negative binomial distributions most often.

In laboratory tests Bioethanomethrin was more than 20 times as toxic as dimethoate when sprayed on nymphs of Melanoplus sanguinipes (Fabr.). Its residual effect on grasshoppers fed treated foliage was relatively insignificant. Toxicity in small field experiments resulted mainly from spray hitting the grasshoppers rather than from their walking or feeding on treated foliage. For 8 days the dimethoate treatment kept numbers of invading grasshoppers significantly lower than those in untreated plots, whereas Bioethanomethrin was ineffective after 2 days. The results indicate that the residual toxicity of the insecticides was of secondary importance in reducing the initial infestation; however, residues do offer a margin of safety against such hazards as poor application, invasion from outside, or continued hatching after treatment.

The alar pocket, located on the upper surface of the hind wing of the male monarch butterfly (Danaus p. plexippus) appears to be of a glandular nature, as is indicated by the cells associated with the androconia and as described by authors reviewed in this paper. Two distinct kinds of modified scales are associated with the cells; one (here termed the "patellate scale") has a relatively broad blade and a deeply penetrating stalk while the other (here termed the "poculate scale") is hair-like, fragile, and penetrates the cell membrane for a short distance. The cell of the poculate scale has a chitinous lip that extends above the plane surface forming a cup-like appearance while the patellate scale is associated with a slightly depressed area. In view of the absence of wing scales at the entrance to the lip of the alar pocket of some species of Danaidae, it has been postulated by many authors that this was caused by the insertion of the male hair pencils into the pocket in order to extract the substance emanating from the gland cells. In the present study there was no evidence of scales being removed from the lip of the pocket and hence it is concluded that such does not take place in this species. It is suggested that the poculate scales, being readily dissociated from the cells, may carry the odour to the outside in a manner similar to that of the spherules or "dust" described for Danaus gelippus berenice. Owing to a lack of experimental data, the function of the alar pockets remains ambiguous.

The trapping devices used in sampling larch sawfly populations (Ives et al. 1968) caught other species of insects as well. The oil traps gave information on the relative abundance of any insects that dropped from the trees to pupate or spin cocoons. One of the more common species trapped in this way, apart from the larch sawfly, was the green larch looper, Semiothisa sexmaculata Packard. It is a solitary-feeding geometrid, and although its seasonal development tends to be later than the larch sawfly, the numbers caught provide some indication of relative abundance from year to year.