An investigation was made of the influence of age of the host (Musca domestica Linn.) in the pupal stage on the oviposition behavior and development of the pteromalid parasite Nasonia vitripennis (Walk.). Five age groups of hosts were employed in 10 pair combinations with an excess of hosts available for selection. Except for the 1-day-old hosts, more of the younger hosts of the combinations produced parasite progeny while the older hosts had a high percentage yielding neither fly nor parasite. Parasite production per pupa was 6.25 on the youngest hosts, with the number decreasing to 4.85 per host at 5 days. Hosts 2, 3, and 4 days old combined with 1-day-old hosts had higher rates of parasitism than when combined with hosts of other ages. The ranking for successful parasitization of hosts, by age of pupae, was 2, 3, 1, 4, and 5 days old.

The weight and size of coccinellid adults varied with species, sex, and feeding. Intraspecies variation in weight was generally similar in the eight species studied. Females were more variable than males in body size. Females of some species were heavier and larger than males, and species can be classified on a basis of difference in the weight and size of the sexes.

An increase in the food supply after a period of food scarcity affected the sex ratio, as the minimum food requirement of females was greater than males. Females increased in weight more rapidly than males after feeding. The availability of food in the field affected the weight and size of some species. Adult water content was influenced by feeding but not by sex or the quantity of food given to the larva.

Males were more abundant in species with small sexual differences in weight and size. The degree of difference in weight and size between males and females may be used as a criterion to select species that are best adapted to survive when food is scarce.

Females of Nasonia vitripennis (Walk.) lived longer, found more hosts, and produced more progeny at high host (housefly, Musca domestica L.) population densities than at lower ones. Because they feed on the fly pupae that they parasitize, the female parasites were able to obtain more food at high host population densities. Starved and unstarved females produced progeny with similar sex ratios. By feeding on parasitized fly pupae when unparasitized ones are scarce, females of N. vitripennis increase their longevity and their ability to oviposit if they subsequently find unparasitized hosts. Females that have fed partly or entirely on parasitized pupae subsequently produce relatively more diapause progeny.

Species of Tetraphleps Fieber known from North America are canadensis Prov., pilosipes Kelt. and And., feratis (Dr. and Har.), latipennis Van D., and uniformis Parsh. Descriptions, host plants, and distributional records for the species are given, and a key is provided.

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.

A survey of the insect fauna in a part of the Sierra Madre Occidental in Mexico was made in 1964 by a party of nine entomologists from the Canada Departments of Agriculture and Forestry. Approximately 50 species of Scolytidae in 20 genera were collected on this expedition and are listed with host relationships and distribution where possible. A brief discussion of the known biology of one of the major economic bark beetles, a species of Dendroctonus, is given. The local weather conditions and the forest composition are discussed generally for the benefit of future collectors in this area.

The following organs were investigated histologically for evidence of neurosecretion during the adult life of Bombus fervidus queens: supra- and sub-oesophageal ganglia, frontal ganglion, ventral nerve cord, corpora cardiaca, and corpora allata. The anatomy and histology of these organs are described, along with the secretory products found in the median neurosccrerory cells. A type of neurosecretion that seems unique to Hymenoptera and that appears later in the life of the queen is discussed.

A new species, Hypolithus pallidus, from Nevada, California, and Arizona is described and illustrated. This species is not closely related to any other in the genus.

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.

N,N′-Hexamethylene bisaziridinyl carboxamide and apholate interfered with the growth of Anatis mali Auct. and prevented it from reaching the adult stage. Coleomegilla maculata lengi Timberlake was unable to grow with hexamethylene bisaziridinyl carboxamide in the drinking water but was able to tolerate a 0.01% solution of apholate.

Myzocallis (Agrioaphis) agrifolicola new species is described from specimens collected on Quercus agrifolia Nee in California. To aid in its recognition a key to the known North American species is given. The key includes Myzocallis (Myzocallis) carpini (Koch), which is a European species previously unknown in North America.

Female Nasonia vitripennis (Walk.) parasitizing housefly (Musca domestica L.) pupae produce a smaller percentage of female progeny at high parasite:host ratios than at lower ones because they fertilize a smaller percentage of their eggs (in this species unfertilized eggs produce male progeny), and because more female than male larvae die on superparasitized hosts. The adult females fertilize relatively fewer eggs at high than at low parasite:host ratios for two reasons. First, they encounter relatively more previously attacked hosts, on which they lay a smaller percentage of fertilized eggs than on previously unattacked ones; second, they more often encounter other female parasites while ovipositing, and this interference reduces the percentage of fertilized eggs they lay.

An olfactometer is described in which an attractive zone is established and maintained in a precisely determined location on the floor (or wall) of an observation chamber and also in the air adjacent to it. Insects must therefore manifest their normal behavior in finding their way to it. The attenuation of the attraction by "background odors" can be studied quantitatively.

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.

Two species of Apidae occur on Ellesmere Island: Megabombus (Megabombus) polaris (Curtis) and M. (M.) hyperboreus (Schönherr). Some observations on their activity are presented. Three nests built on the surface of the ground are described. The colonies were of small size. Nest No. 1 contained only polaris; Nests Nos. 2 and 3 contained polaris workers and hyperboreus sexuals, as adults or brood. Usurpation is suggested to explain the workerless condition of hyperboreus in Nests Nos. 2 and 3.

Most scolytids occupy temporary habitats. Migration, therefore, forms an important part of adult behaviour. Since the extent of migratory movement is positively correlated with the degree of impermanence of the species’ habitat, differences in the behaviour associated with migration must be expected to occur between species. Furthermore, the behaviour of individuals must change in relation to changes in physiology associated with migration and reproduction. These changes have been demonstrated in laboratory studies, and the results suggest that the phenomenon of secondary attraction observed among scolytids may have evolved in conjunction with their utilization of transitory habitats.

Detailed studies on the population dynamics of the imported cabbageworm, Pieris rapae (L.), have been carried out at Merivale, Ontario, since 1959. A method for preparing life tables is described and a mean life table is presented for 18 generations of the species on cabbage. Population data for the preadult period show that there are three age intervals during which extensive mortality may occur: (1) between hatching and the second moult, (2) instars three to five, and (3) during the pupal stage. The analysis of successive age-interval survivals in relation to generation survival showed that the latter is largely determined by the survival rate for (2). Examination of the life tables revealed that a granulosis of the larvae caused by a capsule virus is the key factor in generation survival. Major mortality factors include rainfall and parasites.