Sterility of grasses caused by a constricted brown region, usually in the upper internode, is commonly described as silver top because of the bleached appearance of the inflorescence. Hodgkiss (1908) reported that silver top was caused by the mite, Siteroptes graminum (Reuter), in conjunction with the fungus, Fusarium poae (Pk.) Wr. Brown et al. (1952) found that in the greenhouse several chlorinated hydrocarbons controlled S. graminum. Hardison et al. (1957) reported that S. graminum in combination with F. poae was of little importance in causing silver top of cultivated grasses in western Oregon. They suggested that two thrips of the genus Aptinothrips might be the primary cause. They recommended DDT or heptachlor applied in late April or early May. They also found that post-harvest burning reduced silver top.

In the course of our studies of the Trichoptera of the southern Appalachians during the past few years, considerable material of the genus Lepidostoma has been accumulated. In addition to range extensions and previously undescribed females in various groups within the genus, this material has provided four new species in the vernalis group. With the number of species in this group thus doubled, we believe it useful to provide here a revision of the whole vernalis group, with keys to the males and females. Knowledge of the immature stages is not adequate to permit any systematic analysis at this time.

For more than a decade the sawfly, Neodiprion swainei Midd., has been a serious defoliator of jack pine, Pinus banksiana Lamb., in the Province of Quebec. In 1955 an intensive research program involving several research officers was initiated at the Forest Biology Laboratory, Quebec, to study the insect. Investigations began near the centre of the infestation at the headwaters of the Gatineau River (47° 55′N., 75° 25′W.). The project dealing with the parasites became the responsibility of the author and constituted approximately 25 pcr cent of the total investigations. Integrated with this project were studies on population dynamics, effect of defoliation on jack pine, and predators of the sawfly with emphasis on the small mammals. The primary object of the parasite studies was to concentrate on the life cycles and descriptions of the immature stages and to publish on each species as sufficient information was obtained. Ultimately, it is planned to publish jointly with other members of the team on the role of parasites in the overall mortality complex of Neodiprion swainei.

The Neodiprion sawfly studied in this investigation is an undetermined species which attacks sugar pine, Pinus lambertiana Dougl., in California. The conditions of the infested area were particularly suitable for an investigation of some of the basic factors affecting distribution of cocoons on the ground. The efforts of previous workers (Prebble, 1943; Ives and Turnock, 1959) were complicated by dense stand conditions and deep, variable pound cover. The sawfly discussed here was found in considerable numbers on an isolated, young sugar pine at Grass Valley, California. The tree was 19 feet high, 16 vears old, with s diameter of 5.5 inches. The infestation was presumed to be recent as no effect on diameter growth was found, even though the tree possessed only the current year's foliage. The ground cover was extremely sparse and the soil was a compacted, sandy-clay, typical of many foothill areas in California.

In the course of studles on different species of defoliators in field-spruce stands on the Gaspé coast of the Baie des Chaleurs, Griselda radicana (Wlshm.) occurred fairly commonly in such stands. Although the principal host tree of this insect is white spruce, Picea glauca (Moench) Voss, records of the Forest Insect and Disease Survey show that it has been collected from black spruce, Picea mariana (Mill.) BSP., Colorado spruce, Picea pungens Engelm., and balsam fir, Abies halramea (L.) Mill. Although G. radicana is commonly found across Canada, there are no records that it has ever reached outbreak proportions. These investigations were undertaken since nothing was known on the life history and habits of this insect. The studies were carried out near New Richmond in the Gaspé Peninsula in the summer of 1959.

Recent study of the male genitalia in the Miridae (Kelton, 1959) showed that the Palearctic Stenodema virens (L.) does not occur in North America. The six other species that have been reported in the North American literature are: dorsolis (Say), vicinum (Prov.), trispinosum Reut., sequoiae Bliven, falki Bliven, and imperii Bliven. The three species described by Bliven (1955, 1958) were not available to me for study, however, Bliven (1960) has recently published a paper containing figures of the male genital claspers of these species. These appear to differ considerably from those of virens, vicinum and trispinosum as well as amongst themselves.

In November, 1957, several specimens of adult beetles were collected from beaver pelts taken in the Lake George area of New Brunswick by a local trapper, Mr. Donald Millican. These were referred to me and were later identified as Leptinillus validus (Horn), an ectoparasite of the beaver, Castor canadensis Kuhl, by Mr. W. J. Brown of the Entomology Research Institute, Ottawa. This is the first record of the species having been found in New Brunswick.

In recent ecological studies on the European pine shoot moth, (Rhyacionia buoliana (Schiff.)), where a major objective was to evaluate the influence of different hosts on oviposition preference, larval mortality, insect size, rate of development, and sex ratio, the inadequacy of conventional growth measurements was much too apparent. There was a need to document relatively small differences in larval size and rate of growth on several hosts or from one stand to another. Measurements which showed growth but not weight or volume losses have limited value where the insect under study has a long non-feeding period. Such measurements as body length, and especially head capsule width, obviously belonged in this category. On the other hand, it was felt that dry weight measurements would show both gain and loss. Further, a volume estimate (or body index) would be even more useful, if one could be devised which bore a linear relationship to dry weight. Such an index, while it might involve more than one measurement, nevertheless could be made without destroying the larvae.

A spray chamber provides an efficient means for screening promising insecticide compounds, a procedure that oftentimes serves as a useful preliminary to field tests, which are more expensive and less controllable. In research with residual insecticides for controlling bark beetles, we found a need for rapidly reproducing insecticide deposits on sections of fibreboard to test their toxicity. A spray chamber was constructed for this purpose. Its design and operation are described here.

The American dog tick, Dermacentor variabilis (Say) is abundant in many localities throughout the coastal plains of eastern United States (Bequaert, 1946) and according to Lewis (1960) occurs in sparse numbers as far north as the Bangor area in Maine. In Canada, it is found from Saskatchewan to Nova Scotia (Gregson, 1956) but seemingly only in small numbers and in widely separated areas east of Manitoba. The published information on its occurrence in Nova Scotia is limited to a single record by Twinn (1944) who mentioned that male and female American dog ticks in “considerable numbers” were taken at the upper waters of the Sissiboo River in Digby County. Since its presence in western Nova Scotia in infestation numbers does not appear to be generally known outside that province, it is felt that a note on our observations on D. variabilis might be of interest.

Two aspects of the biological control of R. buoliana are reported in this paper. From 1949 to 1957 rearing techniques were developed for and observations were made of the abundance and biology of parasites received in host material that was collected in Europe (Arthur). From 1955 to 1959 a critical evaluation of the parasites was made, largely based on a study at Elmira, Ontario, of the biology and habits of five representative parasitic species in the field and the laboratory to determine factors that limit their efficiency (Juillet).

The clover seed midge, Dasyneura leguminicola (Lint.), is one of the most important pests in red clbver seed fields in Ontario wherever the double-cut varieties are grown. The larvae feed within the clover florets, destroying the ovaries; if numerous, they prevent many fields from producing seed crops worth harvesting. In 1951 and 1952 and to a lesser degree in 1953, severe damage occurred in seed fields in eastern Ontario (Guppy, 1958); since then populations of the insect have gradually declined. British Columbia, Quebec, and New Brunswick are the only other provinces in Canada from which damage has been reported. However, the insect probably occurs wherever red clover is found in Canada.

In adult populations where females are in excess of males, the ability of the males to mate more than once is an imporcant consideration when predicting the descendant population. Pointing (1961) found that under insectary conditions Rhyacionia buoliana (Schiff.) males are capable of inseminating mlore than one female. Stehr (1954) srates, with reference to a method of mating Choristoneura fumiferana (Clem.) in the laboratory, “Aftcr mating, the male may be discarded; only rarely will it mate succesfully with a second female.” During genetic studies conducted in an insectary on the reproductive capacity of four species of Choristoneura, a technique was used in which individual males were mated to several females. The purpose of the study was to gain genetic information and not to measure sexual activity so that maximum mating opportunities for che males were not provided. In the light of Stehr's observation, it was decided to publish these results since they provide valid but limited information concerning the polygamous capabilities of Choristoneura males.

Insect damage to jack pine shoots (Pinus banksiana Lamb.) in the Lake Nipigon region of Ontario was first reported by Thomas and Lindquist (1956). Since then, a study of insects infesting jack pine shoots has shown that a bark beetle, Conophthorus sp., has been chiefly responsible for shoot damage. A secondary borer, Cimberis elongatus (Lec.), was usually associated with the bark beetle, and because little has been published on the biology of any of the anthribids, the general life history of C. elongatus is outlined here.

In the early 1930's defoliation of red oak, Quercus rubra L., white elm, Ulmus americana L., apple, Malus spp., and other deciduous trees in the South Shore region of Nova Scotia was attributed to the fall cankerworm, Alsophila pometaria (Harr.), and the spring cankerworm, Paleacrita vernata (Peck). The identity of the latter was questioned when adults occurred in the fall. These adults were sutbsequently identified as Operophtera brumata (L.), the winter moth (Hawboldt and Cuming, 1950; Smith, 1950).

The satin moth, occurring widely throughout Europe and Asia as a defoliator of poplars and willows, was first found in North America near Boston, Mass., in 1920. It was first noted in the Maritime Provinces in 1930 (Reeks and Smith, 1956). During 1920 it was found in New Westminster, British Columbia, and in 1921 a larger infestation probably of several years' standing was discovered in Vancouver, which Glendenning (1932) believes to be the original point of introduction into British Columbia. In 1922 the insect was discovered at Bellingham, Washington, and it has since spread throughout western Washington and Oregon.

Nearctic horse flies usually identified as Tabanus (Hybomitra) frontalis Walker or septentrionalis Loew, or simply as T. frontalis septentrionalis complex, have puzzled taxonomists for more than a century. These tabanids (Figs. 1-3), which are among the most widely distributed, most abundant and most troublesome biters of animals and man in North America, are extremely variable, especiallly in color and size. Those who have studied the group have widely different views concerning the taxonomic significance of the variations observed. To date, five nominal species (excluding T. opacus Coq.) have been described from small samples of populations of the group from various parts of Canada, i.e., frontalis and incisus Wlk. (Nova Scotia), septentrionalis Loew and labradorensis Enderlein (Labrador), and canadensis Curran (central Manitoba).

In April, 1959, field crickets were collected in Jamaica and brought alive to this laboratory for study. The great majority of these specimens were Gryllus assimilis Fabricius, and it was assumed for some months that all the specimens collected belonged to this species. The senior author, however, noticed certain specimens that appeared to be distinctive; these were segregated and reared separately, crossing experiments were carried out between them and Gryllus assimilis, and the nymphal stages of both forms were compared. These studies revealed thar two distinct species had been collected in Jamaica, and the unknown species was subsequently determined by Professor L. Chopard as Scapsipedus marginatus Afzelius and Brannius.

Testing arthropods for their ability to transmit plant viruses depends on a satisfactory means of confining test specimens on plant hosts while excluding all other arthropods. This can be difficult with small, active insects such as the Thysanoptera. Screen or cloth capable of confining them must be of such fine mesh that adequate ventilation is prevented and condensation becomes a problem.

The balsam woolly aphid, Chermes (Adelges) piceae Ratz., is widely distributed in Europe and North America. It infests many species of Abies (true firs) and may be found attacking its hosts at elevations from near sea level to timberline (5,000 to 6,000 feet). Because of the great range of environments inhabited by the balsam woolly aphid, its biology differs considerably from one region to another. Perhaps the most variable feature in its biology is seasonal history. Karafiat and Franz (1956) reported three generations per year in central Europe, whereas Varty (1956) noted two and sometimes a partial third generation in Scotland. Balch (1952) found only two generations in the Maritime Provinces of Canada, but Amman noted three and sometimes a partial fourth generation in southeastern United States.