The role that nutrition plays in biological control may be seen in natural environments; but to understand and to make use of this role the principles concerned must be understood essentially in terms of specific chemical substances. A number of principles of insect nutrition particularly relevant to biological control concern the food of the host, the host itself, and its parasitoid. These principles may be generalized into three laws and they are called here the rule of sameness, the principle of nutrient proportionality, and the principle of cooperating supplements. Each is discussed in connection with its application in the laboratory or in natural environments, and a few examples of work relating to each are given. Most examples quoted are from work at Belleville, Ontario, on the parasitoid Pseudosarcophaga affinis Auct. nec. Fallén.

From the revised list of the Lepidoptera of Greenland and from recent work in Ellesmere Island it is shown that almost all the species found in high arctic Canada occur also in Greenland, predominantly in the north, and that this high arctic element constitutes a large fraction of the fauna of Greenland as a whole. It is suggested that this part of the fauna originated entirely from the nearctic by the little-interrupted land route across the arctic islands. The poverty of southerly Lepidoptera in Greenland stands in sharp contrast. It is illustrated by a comparison with the vascular plants and by other comparisons with the Lepidoptera found in the corresponding life zones in North America, and this section of the paper includes the first published list of the Lepidoptera of Baffin Island. It is suggested that this southerly fauna is of adventitious origin, by casual dispersal from overseas (Labrador, Iceland) or perhaps in a few cases by introduction by man. Thus Greenland, in respect of its fauna of southerly type, is an oceanic island of post-glacial age. Similar evidence suggests that Iceland also has been populated mainly in the same way. The conclusions derived from the Lepidoptera apply to several other groups of insects and also to the mammals, including man.

Field and laboratory hatching experiments were conducted from 1960 through 1963 with eggs of Camnula pellucida (Scudder) laid in field cages and collected at fortnightly intervals. Before freeze-up, embryonic development usually reached prediapause level in all eggs laid before the middle of August; these eggs were the first to hatch when incubated in the laboratory or when left in the soil outdoors. Eggs laid later than mid-August showed progressively less embryonic development and consequently hatched later. Viability was highest in eggs laid during the latter half of August; those laid early in the season often suffered from desiccation because of their long exposure to dry soil conditions; those laid towards the end of the season showed declining viability caused, apparently, by low temperatures. The percentage hatch was relatively high in eggs laid before the end of August but declined progressively thereafter; those laid in October rarely hatched. Seasonal hatching patterns were largely dependent upon weather conditions; such patterns were rapidly completed when an extended period of hot, dry weather continued through the hatching period, but often extended intermittently over a month or more when weather was unsettled. The typical diurnal hatching pattern, which also closely followed the temperature regime, commenced in the morning at 0900–1000 hours as soil temperatures exceeded 65°F., rising to a peak about 1100–1200 hours when temperatures reached 85°F., and then generally declined during the afternoon. However, during rapidly changing weather conditions hatching frequently started and stopped as skies cleared and again clouded over. Winter kill occasionally may be an important factor in reducing populations, especially when snow cover is removed by a mid-winter thaw and sub-zero temperatures follow.

The history of the winter moth, Operophtera brumata (Linnaeus), a geometrid introduced into Nova Scotia, is reviewed and an assessment is made of two introduced parasites: a tachinid, Cyzenis albicans (Fallen), and an ichneumonid, Agrypon flaveolatum (Gravenhorst). Functional response curves of both species are discussed, particularly the atypical S-shaped curve of C. albicans, which demonstrates regulatory properties. Biological control efforts to date have been successful but a virus that appeared in winter moth populations may change initial relationships between the introduced parasites and the host.

In Deinocerites, an aberrant offshoot of Culex, the larvae live in water in deep crab holes and the adults also are often found in the burrow. The males have elongate non-plumose antennae and specialized front claws, and often rest on the surface film. In observation cages the males associate with pupae (of either sex) at the surface of the water, hold them lightly with the claws and sense the pupal horns (spiracles) with their antennae. The male perceives the pupa at 1–2 cm. An emerging female elicits a strong response from males up to 15 cm. away; the males fight for possession and mating may be established before the female has fully emerged. The pupal skin continues to attract for several minutes thereafter. Emergence of the adult male was not successfully observed. Probably both pupal attendance and mating response depend on a chemical stimulus, which appears to be non-specific.

The males also make slow exploratory flights near the cage walls, and a mating response may be elicited when their legs touch a resting insect. The response is made to either sex (perhaps more readily to the female) and again is non-specific. The two mating processes are presumably reinforcing, and both seem well adapted to the natural habitat provided the lack of specificity is tolerable.

Several other mosquitoes, all of slow flight and restricted habitat, make similar irregular flights and mate on contact with resting females. Probably this behaviour represents the last phase of mating in more strongly flying (swarming) species, after the sexes are brought together by the auditory response mediated by the plumose antennae. In some mosquitoes the two patterns of behaviour coexist. Assembly at a swarm-marker and recognition in flight must be less necessary in non-dispersing forms in confined habitats, and most of all in Deinocerites. Several other crab hole mosquitoes show convergence or analogies with Deinocerites.

The association with the pupa and the related attraction to the female at emergence find a parallel only in Opifex fuscus; but in Opifex these processes depend not on a chemical stimulus but mainly on vision, as befits an inhabitant of open sunlit pools.

Factors, i.e., time, climate, and isolation, that have or may possibly have influenced the distribution and speciation of Scarabaeidae in North America are discussed. Specific examples of present distributional patterns in the genera Phyllophaga, Serica, Diplotaxis, Onthophagus, Geotrupes and Trox are mapped and described. A general comparison of the distributional patterns is made, and inferences are drawn concerning centers of dispersal and (or) areas of survival of the insect inhabitants of deserts and temperate forests during the various climatic changes of the Pleistocene.

Southwestern Manitoba, a semiarid area subject to periodic droughts, was originally covered by a mixed prairie on light sandy soil. Settlement commenced on the completion of the land survey in 1890. By 1913 all the land was taken up and a cereal grain economy had developed. Soil drifting became a problem and was particularly severe during the drought years of 1929 to 1934. Local species of grasshoppers, Melanoplus sanguinipes (Fabricius), Melanoplus bivittatus (Say) and Camnula pellucida (Scudder) first became pests during a minor drought in 1901 and occurred in a severe outbreak in the major drought period. Recently abandoned fields suffered severe wind erosion and drift ridges of soil provided the most favorable egg laying sites for M. sanguinipes and to a lesser extent for M. bivittatus. The effect of slope of ground on egg deposition and grasshopper behavior in relation to temperature and moisture are recorded. Succulent, introduced weeds and cereal crops supplied abundant food. C. pellucida, a grass feeder, was favored by the planting of cereal crops adjacent to egg bed sites among Carex stenophylla Wahl., and Agropyron smithii Rydb. on the roadsides. Methods of farming designed to prevent wind erosion, the use of herbicides and the grading of roadsides have shown the possibilities of ecological management to reduce grasshopper increase.

The parasitic tachinid Drino bohemica Mesn. preferred the odour of old to that of new growth on the food plant of its preferred host. The new growth directly and indirectly influenced host-finding and host selection by the parasite.

A detailed description of the larva of Melanophila acuminata DeGeer is given with some distinctive characters of the larva of M. fulvoguttata (Harris). A list of the host plants is also given for both species.

Three species of aphids in the subfamily Eriosomatinae are recorded from poplar trees in southern Alberta. Asiphum sacculi Gillette caused galls on leaves of Populus tremuloides Michaux in the foothill and mountain areas. Thecabius populiconduplifolius Cowen caused galls on leaves of Populus balsamifera L. in the prairie area. Pemphigus bursarius L., the lettuce root aphid, caused galls on leaves of Populus nigra var. italica Meunchhausen in a garden. P. bursarius could become a pest of lettuce in southern Alberta.

Metanopedias sicarius Brues, 1910 is considered a new synonym of Trichacis brunneipes Ashmead, 1887. The genus Metanopedias Brues is redefined and Metanopedias brunneipes (Ashmead) new combination is proposed. The latter species is redescribed and illustrated, its geographical distribution and host relationships are listed and discussed.

The majority of caddisflies selected for discussion in this paper are from Mexico. The Mexican Trichopterous fauna should contain a large number of genera and species, however, relatively few have been recorded, or described from that country. The phylogeny of many nearctic species will be better understood when our knowledge of the Mexican fauna is more complete. With this as the objective, most of the new species selected for description herein will further elucidate our knowledge of the Trichoptera.

One new species of Wormaldia, four new Polycentropus, two new Limnephilus and two new Oecetis have been selected for description. The unknown female of Limnephilus discolor is described. Types are in the senior author's collection unless otherwise indicated.

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.