Large numbers of black flies, mostly Simulium venustum Say, were labelled as larvae with 32P and released in rapids in the Chalk River near the village of Chalk River, Ont., to complete development and disperse as adults. Flies were trapped over a 900 square mile area for 3 months after the release, and radioactive flies from the traps were identified at CRNL by means of an autoradiographic technique. The distance travelled by the flies could be described by a normal distribution curve, with the average migration between 5.8 to 8.2 miles. A few individuals were trapped at a distance of 22 miles 2 days after emergence, and some crossed the Ottawa River which is at least a mile wide at the point nearest the release area. Some traps caught very high numbers of radioactive flies, one at about 6 miles from the release center accounting for more than 1300 tagged flies. The traps giving the highest number of tagged flies (e.g., > 100) were clustered in two distinctive areas, one west and one large area south of the release point. The results indicate that control measures should be applied to black fly streams at least 10 miles from critical areas such as towns.

The biology of Coenagrion angulatum Walker and C. resolutum Hagen in Saskatchewan has been studied. In these species embryonic development begins as soon as the eggs are laid and is completed in the field within 3 weeks. Larval development is rapid and larvae in the final instar were first collected before the middle of September. Development ceases during the first 2 weeks of October when the water temperature is about 2 °C. By this time the majority of larvae are in the last three instars. Larvae overwinter frozen in the ice 15 to 20 cm below the pond surface. They are able to survive temperatures as low as −5° to −6 °C though these extremes are not normally experienced in the field because of snow cover. Although the study pond filled with runoff water by mid-April no change in the larval population structure occurred until mid-May. Emergence, which is highly synchronous, begins in the last week of May. However, it is governed by the prevailing air and water temperatures, and occurs only when the mean daily water temperature exceeds 12 °C and the mean maximum air temperature reaches 20° to 21 °C. Most insects emerge within 10 days of the first appearance of the adults. Sexual maturation takes about 1 week. Oviposition occurs while the pair are in tandem. Preferred oviposition sites are the submerged portions of stalks of floating plants such as Utricularia, Ranunculus, and Potamogeton. The observations are discussed in terms of the species’ ability to survive the climatic extremes of central Canada.

The spectrum of geographical ranges of species of Odontiinae in North America differs from that of related subfamilies such as Scopariinae, Nymphulinae, Glaphyriinae, Evergestinae and Pyraustinae, though all these subfamilies have wide global ranges. Of 57 species only five are primarily eastern. Of these, three are tropical species that enter southern Florida, one is a northern disjunct closely related to Neotropical species, the fifth is widespread in eastern North America and has no obvious close relatives. Six western species are alpine or subalpine. Three of these belong to one superspecies ranging from Oregon to Baja California, two others are Sierran or Sierra-centered, one is a Colorado disjunct with close relatives in the mountains of Europe and Asia. One additional species is restricted to Colorado; its ecology is unknown but is most likely temperate. There is one restricted temperate species in California and Oregon, one in Utah, and one in northwestern Arkansas. Five primarily western species or species pairs have wide temperate ranges, four of them range south into the tropics. Three of the members of this range class belong to the single genus Frechinia, comprising five of its six species. The remaining 34 species belong to the southwestern eremic class. Of these one is limited to the southwestern Great Basin; 12 are centered in southern California and western Arizona, but two of these are represented in the dry interior of Washington, one by a disjunct population, the other by a vicarious species; 15 are centered in southern Arizona and(or) New Mexico; six are centered in western Texas. There is a comparable development of the subfamily in the arid areas of the Old World, especially in western and central Asia. The relationship between the New World and Old World eremic complexes is probably multiple. It appears to be mainly at the suprageneric level.

Diagnostic characters of Euxoa mimallonis (Grt.) and E. biformata Sm. are discussed. Three species are described as new: condita from Forestville, Que., shasta from northern California, and intermontana from the Great Basin and Colorado Plateau. Adults and genitalia of the species are illustrated and a key to species is included.

The feeding rate of Phormia regina is constant over the whole feeding period, contra-pressure of the crop contents having no effect. The mechanism by which contra-pressure effects are negated involves the function of two previously undescribed structures in the crop and crop duct. These structures, described in the text, act as valves and a pump. An alternative mechanism, by which contra-pressure effects could be negated in insects lacking these structures, is discussed. The physical effects of variation in the feeding position of the labellum, in response to changes in the physical nature of the substrate, are discussed in relation to the feeding rate. The feeding rate is shown to be higher on semi-liquid substrates.

The nine species of Coproporus Kraatz and Cilea silphoides (Linné) of America, north of Mexico are revised. No new species are described. Coproporus maneei Scheerpeltz is placed in synonymy with C. ventriculus (Say). Based on examination of type material, a number of Latin American species formerly considered as synonyms, are recognized as valid species. These include convexus (Erichson) and ignavus (Sharp) which are distinct from hepaticus (Erichson); and terminatus (Erichson) which is distinct from rutilus (Erichson).

Coproporus rutilus piceorufus from Argentina and Brasil and C. rutilus obscurior from Panama, both described as aberrations by Bernhauer (1918), are elevated to specific status. Coproporus segnis, formerly known from Mexico and Panama, is reported from the United States for the first time.

The usage of both Coproporus Kraatz and Cilea Jacquelin du Val has been confused in previous publications. The synonymy and priority of Coproporus vs. Erchomus Motschulsky and Cilea vs. Leucoparyphus Kraatz are discussed. Each genus and species is described and the distribution of each species is mapped. The male genitalia of each species are drawn and the major diagnostic characters are illustrated with scanning electron photomicrographs. A diagnostic key to all the taxa is included.

Defoliation by the birch casebearer, Coleophora fuscedinella Zeller, the most important pest of white birch, Betula papyrifera Marsh., in Newfoundland, is correlated with leaf size but the differences in defoliation associated with leaf size are too small to be of practical importance. Thus, a sample of at least eight leaves from either the top crown quarter or from mid crown will give consistent estimates of tree defoliation, and 14 trees should be sampled to classify a stand for appraisal surveys or for evaluation of damage to scenic areas. Evaluation of stand defoliation in three broad classes is recommended: up to 30% defoliation appears as light browning not noticed by the general public, 30% to 90% results in distinct browning, and over 90% defoliation denotes intensive browning and bud and branch mortality.