Sterilization of male and female Ips confusus (Coleoptera: Scolytidae) exposed to gamma radiation (Co60) as newly emerged adults was almost complete at levels exceeding 7500 r and 10,000 r, respectively. Mating behavior of males as expressed by sperm transfer was unaffected by dosages up to 60,000 r. The capacity of beetles of either sex to establish galleries was not affected significantly below this dosage, but female gallery pattern was altered above 15,000 r. Longevity was reduced at levels greater than 5000 r. LD50 for males occurred at 11.5 days at 7500 r and 29 days in the controls. Mortality of progeny resulting from males irradiated at substerilization levels was higher than in the controls. The dosage to achieve significant population reduction with minimum effect on longevity and other biological activity is estimated to lie between 6000 and 7500 r.

These studies indicate that this sterilization technique may have promise in the control of bark beetles. The necessity for rearing large numbers on artificial media could be circumvented by mass trapping utilizing their natural sex attractant and by mass rearing in cut host material in the laboratory.

The faunal changes in the crown stratum of a newly established red pine plantation were observed during the first five years of growth. The crown faunae of three older stands planted in 1950, 1939, and 1929 were sampled throughout the growing seasons of four consecutive years by a technique employing pyrethrum insecticide.

The stands represent four stages in the development of a red pine community over a period of 35 years, and the presence, distribution, density, annual and seasonal fluctuations, species succession, and food relations of arthropod taxa are discussed.

Species colonizing trees in the establishment stage are largely replaced in the transition stage by a species-complex that persists throughout the succeeding monoculture and young-forest stages. Arthropod density in relation to crown size increases rapidly until the trees are about 15 years of age, and then declines. The pattern of seasonal abundance is dominated by a few species. The ratio between parasite–predator and prey species remains remarkably stable throughout the three older stages of the community.

A search for natural enemies of Hippelates eye gnats in Jamaica and Trinidad in 1963 resulted in the discovery of four pupal parasites, Trichopria nov. sp., Spalcmgia drosophilae Ashmead, a species of Spalangia and Encyrtidae, and one larval parasite, Trybliographa nov. sp., in Jamaica. What were probably phoretic mites of the Acaridiae infested up to 6.1 per cent of the adult populations in Jamaica. No parasitic Hymenoptera were found attacking Hippelates in Trinidad. Parasitization in Jamaica sometimes approached 40 per cent, but overall parasitization with all host exposures considered did not exceed 2.5 per cent. The effect of predators on naturally breeding Hippelates populations in both Jamaica and Trinidad seemed highly significant, and predominant species are listed.

Two of the four Nearctic species of Fervidobombus occur in southern Alberta. One, Bombus californicus, is confined to the wooded areas whereas the other, B. fervidus, is confined to the prairie. When given a choice, B. fervidus nested in underground hives and B. californicus mostly in surface hives. Queens of B. fervidus sometimes made false nests at tunnel entrances. Both established nests late but were not the latest species to establish in their respective habitats.

B. californicus made 10 ± 3 and B. fervidus 8 ± 1 cells in the first broods. Both constructed pollen-pockets beside and beneath the broods of young larvae destined to become workers. Queens required about 27 days to rear the first workers. The workers of succeeding broods were progressively larger, the last ones produced being almost as large as queens. B. fervidus produced more broods of workers than B. californicus; colonies of B. fervidus averaged 247 individuals, the largest being 287, whereas those of B. californicus averaged only 52, the largest being 97.

Males of B. fervidus were attracted to nests containing new queens. New queens of B. californicus dug about 1.5 in. into the ground to hibernate.

Females of the cuckoo bee, Psithyrus insularis, succeeded in having their young reared to maturity in nests of B. californicus. The big-headed fly, Physocephala texana, parasitized founding queens of B. fervidus.

Cocoons of the European pine sawfly were exposed in rodent-proof trays to determine what parasites attack this pest in southern Ontario. Exposures at 17 localities showed that two introduced parasites, Dahlbominus fuscipennis (Zetterstedt) and Pleolophus (= Aptesis) basizonus (Gravenhorst), are firmly established throughout the distribution of the host. The former parasite has spread more than 30 miles and the latter at least 70 miles in approximately 20 years. The number of trays found by each species varied considerably with locality. In general, the number of native parasitic species obtained tended to increase with age of infestation, with Mastrus aciculatus (Provancher) being the most prevalent.

Kristotomus simplex is described from Japan. It is the most primitive member of its genus and appears closely related to Orthomiscus Mason. A key is given to distinguish the Japanese species of Kristotomus, Orthomiscus, Kerrichia, and closely related forms.

The effect of attack by the ambrosia beetle Trypodendron lineatum (Olivier) on log attractiveness was studied using "greenhouse" cages, in which solar heating causes release of odor-bearing air beneath glass-barrier traps. In all eight replicates of a test, attack by female beetles was followed by a marked increase in attractiveness of logs. This "secondary" attraction was strong within 2–3 days after attack, continued for many weeks if females remained alone, but disappeared following mating.

Four of ten common varieties of cabbage tested at Ottawa from 1960 to 1963 were slightly or moderately resistant to Hylemya brassicae. Red Acre was the most resistant and Viking Golden Acre the most susceptible of the ten. Red Acre and Danish Ballhead were damaged less than Viking Golden Acre and harbored fewer maggots. Market Topper and Jersey Wakefield were also damaged less than Viking Golden Acre but harbored as many maggots. Resistance in Red Acre and Danish Ballhead was evidently due chiefly to low-attractiveness, and in Jersey Wakefield and Market Topper to tolerance. Differences in plant height and width, either between or within varieties, had little effect on the numbers of eggs laid on the plants. Of the Hylemya specimens identified, 99% of the eggs, 89% of the larvae, and 83% of the pupae were of H. brassicae and the remainder were of the H. liturata-platura complex.

A method of mounting Diptera, Lepidoptera and other insects preserved in alcohol is described.

Porcupinychus abutiloni, a new genus and species of mite, commonly found on Abutilon indicum in the Karachi area of West Pakistan, is described and illustrated.

Mosquito-repellent chemicals tend to absorb far infrared radiation (below 600 cm.−1) more strongly than do non-repellents of comparable molecular weight. The correlation is probably less direct than was previously supposed, and is hardly strong enough to be used as a primary screening technique.

Two undescribed species of the genus Heptagenia of the maculipennis group are described and illustrated. Heptagenia jewetti n. sp. is known from Oregon, and H. petersi n. sp. from Wyoming and Utah.

The elm spanworm, Ennomos subsignarius (Hübner), a defoliator of oaks and hickories in the Southern Appalachians, was reared under three population densities — one, two, and four larvae per cage. The size of the group influenced to a degree the time spent in the larval stage, but was even more significantly related to the duration of the hatch to adult period. Although male pupal weight was not related to group size, female weight and fecundity were. Females reared singly had significantly greater pupal weight and fecundity than those reared in groups.

The initial spring loss of porential bumblebee colonies is the result of parasitism of the overwintered Bombus queens by the nematode Sphaerularia bombi Duford. The infested queens commonly have one or two nematodes in the body cavity and may have as many as six (Medler 1957), which effect sterility. Palm (1948) pesenied the histopathology of the nematode based on material collected in the vicinity of Lund, Sweden, where the infestation of the nematode was so intense that healthy queens were difficult to collect.

Sterile male codling moths, exposed as pupae to 40 krad of gamma radiation and released in an abandoned 20-tree apple orchard for 3 years, reduced the percentage of fruits injured by mature or almost mature second-brood larvae from 4.94 to 0.05. Numbers of sterile males released, ratios of sterile to fertile males during peak emergence of first-brood moths, and numbers of overwintering larvae were: 1961 (3 DDT sprays applied) — 0, 0:1, 400; 1962 — 21,300, 8:1, 957; 1963 — 67,500, 21:1, 43; 1964 — 89,200, 715:1, 6.

Using a series of photographs, the mechanism of host location and oviposition by Rhyssa lineolata (Kirby) are described.

The dispersal flight of the Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, is oriented toward fresh windthrown and cut trees when these are present in the stand, the beetle being attracted by oleoresin, particularly its alpha-pinene, camphene, and limonene fractions. In the absence of such material the pioneer beetle dispersal appears to be rather uniform throughout the stand. This host attraction precedes the beetle attraction which is produced by unmated females shortly after entering the host and which results in mass concentration of beetles around the center of attraction. Of these two phases in the attraction process, the secondary attraction is far stronger than that caused by the fractions of the host oleoresin.

Attraction centers are established only in freshly downed trees and in standing trees of subnormal physiological condition under both latent and epizootic conditions; however, under epizootic conditions, the beetles can invade even vigorous trees in the perimeter of attraction. The survival of such trees depends on their ability to exude oleoresin, which in turn is influenced greatly by environmental factors. The susceptibility of trees to successful beetle invasion is characterized by their oleoresin exudation pressure, which reflects water disturbances in the tree. Diurnal and seasonal fluctuations of the resin pressure are discussed in relation to beetle flight and invasion, and the resin effects upon the beetle (both mechanical and chemical) are considered. The beetles are found to be repelled by Douglas-fir resin and its fractions, i.e. alpha- and beta-pinene, camphene, limonene, terpineol and geraniol, when tested at close range in the laboratory.