Larval surveys were conducted in Winnipeg environs during the summers of 1967 and 1968. The species, density of larvae, the relationship between rainfall and larval abundance, and the species of pest importance were studied in detail. Aedes vexans was the most numerous mosquito found both in the larval and adult stages. Aedes dorsalis and Aedes spencerii were also of pest significance during each season. An association between the abundance of A. vexans larvae and the proximity of these to an adult blood source, mainly beef and dairy cattle, was observed.

The description and designation of a neotype, Plastobelyta gallicola Kieffer, and an additional distribution record of Espinosa nothofagi Gahan belonging to the subfamily Brachyscelidiphaginae (Pteromalidae: Chalcidoidea) from Chile, are discussed.

Flash photography of the wings of a decticine katydid, Metrioptera sphagnorum (F. Walker), during stridulation, indicates that major trains of sound pulses of both song modes coincide with wing closures. The song mode characterized by intense ultrasonics is generated by tooth–scraper interactions over an interval of approximately 60 teeth at the lateral end of the file. A more medial file region is employed for the audio-dominated mode. Tooth removal confirms the role of different file regions in mode generation. Each pulse of the ultrasonic mode closure is a wave train of 10–15 waves of uniform amplitude, approximating a pure tone frequency of 33 kHz.

There are no valid reasons to believe that the allegedly successful biological control attempt against Cephus pygmaeus (L.) in Ontario was in fact a success. There are definite indications that it was a failure.

By a method of micro-cauterization, in which a small area of tissue may be destroyed without bleeding, it is indicated that the pigmented areas on the pupa of the monarch butterfly, Danaus p. plexippus (Linnaeus), are involved in the distribution or formation of wing scale colouration. The paper deals with experiments involving one pair of such areas, namely the alar (Al) pigmented macula which, like the median notai macula, effects apical wing colour on the prothoracic wings.

Sterility induced by gamma irradiation of the adult male tobacco budworm, Heliothis virescens (F.), was studied in two colonies, one was reared in the laboratory for more than 60 generations (laboratory strain) and the other reared for fewer than 9 generations (wild strain). When irradiated males were crossed with untreated females, the percentage egg hatch for each dose was lower with the laboratory than with the wild strain. When laboratory and wild females were crossed reciprocally with irradiated males, the fertilities were similar to those of the laboratory and wild strains, respectively. When irradiated males were crossed with female progeny from reciprocal crosses, the percentage egg hatch was similar to that of the wild strain.Wild strain females were nearly monogamous for the first several generations, but F0 females mated nearly as frequently as females of the laboratory strain.

Field studies enabled the identification of some limiting factors to which parasitoids were exposed in exploiting the sawfly host, Neodiprion swainei Middleton, and aspects of their quantitative and qualitative impact on the host population. Emergence patterns and flight activity of parasitoids in the spring indicated that larval parasitoids were vulnerable to hyperparasitism by cocoon parasitoids. Although cocoon parasitoids were limited by a shortage of time in which to exploit the host in the spring they still reduced the overwintered host population by 66% in 1969. All forms of predation caused less than 10% sawfly mortality so parasitoids formed the major mortality factor in the spring. Sawfly in prolonged diapause appeared to be immune from cocoon parasitoid attack and thereby efficiency of these parasitoids was limited. However, cocoon parasitoid activity was selective on sawfly that would normally have emerged early in the season and thus delayed the average development of the host population. The complex food web based on the sawfly host provided a sensitive buffering mechanism to produce a degree of stability in the host–parasitoid interaction. The composition of the parasitoid faunae before and after establishment in N. swainei populations of the introduced Pleolophus basizonus (Gravenhorst) indicates the rapidity with which the parasitoid became influential in the complex.

Aulacorthum clavicornis, A. pterinigrum, and A. scabrosum are described and illustrated and a key to Canadian species is given.

Female and larva of the new sawfly Susana fuscala are described and illustrated, based on specimens collected in British Columbia. The new species, feeding on the foliage of Juniperus scopulorum Sargent, is separated from the other six Nearctic species.

Adult sexing characters were found by comparing the arrangements of spines on the elytral declivity. Callows were distinguished by observing the male vas deferens through the semi-transparent pronotum. In pupae, sexing characters were found to be located in the posterior abdominal segment of both sexes.

Four new species of Dichrooscytus Fieber are described: flagellatus and rufusculus from British Columbia, and rostratus and rubidus from Alberta and British Columbia. New records for Canada are: convexifrons Knight, flavescens Knight, irroratus Van Duzee, latifrons Knight, rainieri Knight, ruberellus Knight, and rufipennis Fallen. Key to species, additional records on distribution and host plants, and illustrations of the male genitalia of all the species occurring in Canada are presented.

A series of low-volume spray treatments were conducted to study the contact and residual effect of two concentrations of the insecticide phosphamidon to fourth instar spruce budworm, Choristoneura fumiferana (Clem.), on balsam fir, Abies balsamea (L.) Mill, and red spruce, Picea rubens Sarg. Treatment of sprayed larvae on sprayed trees, unsprayed larvae on sprayed trees, and sprayed larvae on unsprayed trees, resulted in two principal conclusions: (a) Higher concentrations of phosphamidon (1% versus 0.5% active) accelerated mortality in all instances and (b) no statistical difference (P = 0.1%) was found in the final mortalities between treatments in which only the foliage was treated and where both larvae and foliage were treated with phosphamidon.

In the phylogenetic classification of the Lepidoptera, the position of the genital opening and its modifications help to clarify the relationship of the Zeugloptera to the lepidopterous suborders. Three different systems of the suborder classification of the Lepidoptera, into Homoneura and Heteroneura (Tillyard, Imms, etc.), Monotrysia and Ditrysia (Borner), and Dacnonypha, Monotrysia, and Ditrysia (Hinton), are not supported by evidence obtained in the study of the female genitalia.The development of the female terminalia is closely associated with the mode of oviposition. Several types of female terminalia are found in the primitive Lepidoptera (Hepialidae, Neopseustidae, Tischeriidae, Lyonetiidae, Agathiphagidae, Tineidae, Nepticulidae, and Eriocraniidae). They are divided into four categories: hepialid type — the eggs are dropped randomly; typical lepidopterous type — the eggs are laid on the surface of food plants; eriocraniid type — the eggs are laid inside the food plants; tineid type — the eggs are laid in crevices of food. Each of the types is derivable from the types occurring in Neopseustidae, Tischeriidae, Agathiphagidae, and Eriocraniidae, respectively. These types are still far removed from the type of female terminalia in Micropterygidae of the Zeugloptera.The modes of egg-laying as well as the morphological characters of the female genitalia must be taken into consideration in suborder classification of the Lepidoptera.A genealogical tree based on the female terminalia suggests four main branches: hepialid branch — includes Neopseustidae and Prototheoridae; typical lepidopterous branch — includes all Ditrysia and Nepticulidae; tineid branch — includes only Tineidae; eriocraniid branch — includes Incurvariidae, Prodoxidae, Adelidae, and Heliozelidae.

A study of the ant populations was made through a transect of mid-continent North America from Churchill on Hudson Bay and various localities around the Great Lakes to Iowa and northern Illinois. Data were obtained from extensive personal collecting and from literature sources. The results were assembled and discussed within an ecological framework provided by Merriam’s life zones, and showed a regular diminution in the variety and wealth of the ant faunas progressing from south to north. Though the number of species at Churchill is extremely reduced, ants nevertheless do occur there as established reproducing colonies, even in the presumed tundra habitats. These forms which exist so far north represent a highly impoverished remnant of richer faunas further south. Although none of the species is peculiar to the area, each must be tolerant of high boreal environments. A total of 135 species and subspecies are listed for the Carolinian and Alleghenian zones combined, 43 taxa for the Canadian Zone, 4 taxa for the Hudsonian Zone, and 4 also for the Arctic Zone. Comparisons with the recorded ant faunas of the Rocky Mountains of Colorado were made with respect to the corresponding zones, namely, the Plains (Upper Sonoran), Foothills or Submontane (Transition), Montane (Canadian), Subalpine (Hudsonian), and Alpine (Arctic) zones, and appropriate similarities and differences noted.

Intertidal Chironomidae (Diptera) are represented on the coast of British Columbia by Paraclunio alaskensis Coquillett and Saunderia pacificus Saunders, S. marinus Saunders, and S. clavicornis Saunders. The larvae, pupae, and adult males can now be easily identified with the aid of the new keys. The mentum of the labium was found to be an especially useful taxonomic character for the separation of the larvae of these four species.

Intertidal Chironomidae (Diptera) are represented on the coast of British Columbia by Paraclunio alaskensis Coquillett and Saunderia pacificus (Saunders), S. marinus (Saunders), and S. clavicornis (Saunders). These species inhabit a variety of rocky shore types, being found on exposed as well as protected shores, but are not present on exclusively sandy shores. Their range extends at least to the Queen Charlotte Islands, the most northerly area collected during this study. S. clavicornis is the most ubiquitous of the four species while S. pacificus is the rarest.Within their habitat larval distribution is contagious and is well described by the negative binomial distribution. It is probable that their clumped distribution is due to environmental factors rather than active aggregation. Larval densities of 4316/ft2 were recorded for Saunderia spp. and 1613/ft2 for P. alaskensis. Larvae fed on green algae and diatoms and it was demonstrated that they can select certain groups of diatoms from the substrate.Adult emergence occurs throughout the year but is most intensive in the fall and least in the late spring and summer. Generally, larval population fluctuations follow adult emergence trends. It is hypothesized that larval population fluctuations are caused by a combination of overlapping multiple generations and differential larval growth rates at fluctuating temperatures, coupled with varying lethal environmental factors at different times of the year. Developmental times at 10 °C from egg-laying to adult emergence was 110 days for S. clavicornis, 150 days for S. marinus, and 204 days for P. alaskensis.

Although heterogony has yet to be proved for the oak gall producing species of Cynipidae, Plagiotrochus tumificus O.S. and P. scitula Bass., the laboratory rearing of the male and female individuals from the vernal galls of these two species indicates that the mother insects in the former species are mostly amphitokous, while those in P. scitula are arrhenotokous and thelytokous. Amphitoky is shown for Callirliytis operator O.S. which is known to be heterogenous.Cynipid inquilines and chalcid parasites were reared from several cynipidous oak galls in the area. The inquiline and parasite fauna of any particular gall depend on the form of the gall and not on the species of the gall producing cynipid. None of the inquilines and parasites reared in this study is identical with known palearctic species. Most individual inquilines and parasites emerging from the vernal galls emerge in the summer, but a few overwinter in these galls and do not emerge until the following spring.