Over a century ago Peck (4) observed that open-growing stands of white pine, Pinus strobus L., were subjected to greater weevil damage than were those growing in mixture with, and shaded by, other tree species. This observation, which was later corroborated by Graham (2) and MacAloney (3), suggested possibilities of silvicultural control of the insect by means of plantation growing of white pine in various kinds of mixtures. The results of this work were recently assessed in a review paper by Belyea and Sullivan (1), who concluded that further silvicultural control measures be curtailed until the physical and biological requirements of the insect were defined in terms of measurable factors of the environment. Investigations were carried out (6, 7) to establish the conditions of temperature, light, and moisture favourable for feeding, copulation, and oviposition of the adults, and development of the larvae. The results indicated that P. strobi is well adjusted to the environmental conditions in open stands of white pine, but that the limitations imposed by weather on weevil oviposition might be a major factor contributing to the inability of the insect. to adapt readily to the climate of many shaded stands. The present paper is an attempt to assess the role of weather and the physical characteristics of white pine leaders, hereafter called leaders, in limiting the successful invasion, by the weevil, of white pine stands growing as partially suppressed, understory trees. Emphasis is placed on providing an understanding of the differences in the climate of weevil habitats, adult feeding and oviposition behaviour, and survival of weevil populations in exposed and shaded stands of white pine. In addition, records were obtained for the purpose of forecasting differences in both the timing and amount of such acts as oviposition and feeding in populations in the two habitats.

During studies of the locomotory behaviour of blowfly adults, one of us G.W.G.) developed a simple tilting-type actograph wherein an electrical circuit was opened or closed each time a fly moved from one end of a small cage to the other. Circuits from six such cages were connected to solenoid-activated pens on an event recorder so that movements in each case were recorded as crosslines on the respective pen records. At peak activity, an individual fly may activate a pen up to 4,800 times during a 24-hour period. With six flies active at the same time, abstraction of a day's chart was a formidable and time consuming task. In analysing the data, activity counts over consecutive half-hour periods proved adequate, and some method was sought whereby half-hour activity records could be obtained. Six electrically operated counters were arranged so that they were activated by the closing of contacts attached to their corresponding pens. Thus, each time an actograph circuit was closed, a pen was activated producing a crossline on the chart, and a count of fly activity was registered by a corresponding counter. To simplify the situation further, some method of automatically photographing the counter dials at half-hour intervals was required. The photographic apparatus subsequently developed proved to be simple, inexpensive, and reliable. Because it is adaptable for use in many situations requiring photographic records at pre-set intervals, details of its construction arc reported herein.

Previous work by Kinghorn and Chapman (1959) has shown that in coastal British Columbia, the ambrosia beetle Trypodendron lineatum hibernates in the forest litter or duff at various distances within forest edges in the vicinity of brood logs. It was pointed out that further study was required to determine the characteristics of the optimum hibernation sites. It was mentioned that stand density, shade, aspect, slope, and the nature of the duff might be factors controlling the selection of the place of hibernation. The base of trees and the relatively deeper duff, characteristic of this situation, was reported to be the location of the larger populations of hibernating beetles although the level of population was found to vary greatly both from tree to tree and in depth within different forest edges.

Extensive trials showed that a nematode of the family Neoaplectanidae and its associated bacterium did not act as a permanent or temporary biological control agent against the Colorado potato beetle, Leptinotarsa decemlineata (Say). These trials and the causes of the failure were investigated for a number of years at Belleville; the initial test was reported by Welch (1958). The nematode, commonly known as DD 136, was discovered in codling moth larvae by Dutky and Hough (1955). It is ingested with food by the host, passes through the gut wall into he haemocoele, and releases a bacterium that multiplies rapidly and kills the host. The nematode feelds on the body contents of the dead host, passes through several generations, and eventually leaves the host as an infective larva. Dutky, and we, found that many kinds of insects can be infected by the nematode in the laboratory. It may be reared in large numbers by infecting larvae of the greater wax moth, Galleria mellonella (L.). The larvae die within 36 hours at room temperature and are then placed on wet filter papers in a trap designed to recover the nematodes that emerge from the dead hosts. Storage of the nematodes in water at 45° F. for a month or more causes no decrease in vitality or infectivity, so that large numbers may be accumulated for field trials. These sturdy animals may be applied with a mechanical sprayer at pressures of 100 psi without injury.

The spruce budworm, Choristoneura fumiferana (Clem.), is indigenous to most of the boreal forests in Canada and adjacent Eastern and Western United States. Throughout most of this range the budworm maintains a one-year cycle, overwintering as second instar larvae. In some mountainous areas of Alberta and British Columbia, a form of the budworm has a two-year cycle and over-winters as second instar larvae in the first year and as fourth instar larvae in the second year. The habitat temperatures of these two forms were investigated and related to rates of development in an attempt to discover the environmental factor which maintains the two-year cycle budworm as a distinct form even though it is geographically surrounded by the one-year cycle budworm.

The females of many species of chalcids, braconids, pteromalids, and ichneumonids feed on the body fluids or hemolymph of their host. The fact that the adult males do not partake of this food indicates that such feeding may be associated with egg production. Carbohydrate foods, in addition to the body fluids of the host, are essential to egg production in certain species. Feeding on the host by females of certain hymenopterous parasites increases their value as control agents. This feeding sometimes may be more important than parasitism as a cause of host mortality. Itoplectis conquisitor (Say), a host feeding parasite, is considered in this paper.

The abdomen, as in other muscoid flies, is composed of a preabdomen of five pregenital segments, of which terga 1 and 2 are fused, thus giving the appearance of four segments. Sterna 1-7 or 1-8 form a relatively narrow chain of ventral segments (Fig. 11). The postabdomen, or genital segments, comprise segments 6-10, some of which are reduced, absent, or modified in other ways. The post-abdomen of the Sarcophagidae and Tachinidae usually is “fixed” (not retractable), whereas in the Muscidae and Calliphoridae it commonly is in the form of a retractable ovipositor, which is narrow and elongated when extended but in repose telescoped within the abdomen.

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 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.

Aptesis basizona (Grav.), a parasite of pine sawflies in Europe, was propagated at Belleville, Ont. (Green, 1938) for release against the European spruce sawfly, Diprion hercyniae (Htg.), the European pine sawfly, Neodiprion sertifer (Geoff.) and other Diprionidae. Development of the insects in the laboratory was allowed to continue until feeding was completed and cocoons were spun, and was then retarded by placing the insects in cold storage pending shipment to release areas. Frequently stock for propagation was incubated after a period of cold storage, and occasionally the schedule was interrupted by decreases in the reproductive capacity of the adults. It seemed that there was some relationship between the fertility of the adults and the temperatures at which the immature stages were held, both while feeding and after they had reached the fully-fed stage. Experiments were initiated to investigate this hypothesis.

Although there are many reports on the control of the pea aphid and its effect on the yield of peas, few are available on the effect of the aphid on the yield of alfalfa hay, particularly on irrigated land. The experiments of Cook and App (1956) and Franklin (1953) were done under climatic and edaphic conditions different from those encountered in southern Alberta. Outbreaks of the aphid occur only occasionally in Alberta, but in 1957 it was very abundant in some irrigated alfalfa fields. This is a report on the effect of the aphid on yields of alfalfa hay in an irrigated area in southern Alberta.

The remarkable discovery that the larch sawfly, Pristiphora erichsonii (Htg.), had developed an immunity, in parts of North America, to one of its principal parasites, the ichneumon, Mesoleius tenthredinis Morl., followed Lejeune's report (6) that parasitism rarely had exceeded 5 per cent in Manitoba and Saskatchewan since 1940. Muldrew (8, 9) showed that the immunity phenomenon resulted from the formation of a phagocytic capsule around the parasite's egg. The occurrence of parasite resistance by the larch sawfly in Minnesota and Wisconsin was observed in 1952 (2, 4).

The genus described below appears most closely related to the genus Gronocarus Schaeffer (1927, p. 213). The description is based on a unique female collected in eastern Texas within a few miles of the Louisiana state line.

In recent years the black cutworm, Agrotis ypsilon (Rott.), has been the predominant species of economic importance in southwestern Ontario. Relatively small populations of this insect can cause extensive damage to widely-spaced cash crops such as tobacco, tomatoes, and sugar beets.

Present control recommendations are based primarily on results obtained from field trials. These results are often inconclusive because cutworm outbreaks are difficult to predict and usually unevenly distributed. Therefore, it is necessary to develop laboratory techniques to assist in assessing the comparative toxicity of insecticides and their formulations.

In 1958, intensive studies on the population dynamics of the diamondback moth, Plutella maculipennis (Curt.), on cabbage were initiated in long-term study plots at Merivale, Ontario. The object was to construct ecological life tables (Morris and Miller, 1954) for successive generations of the insect, and, ultimately, to develop a mathematical model describing survival of field populations. This paper reports on the variation between samples of immature stages of the moth, and between some of the mortality factors affecting its abundance, and on the use of these data in designing a sampling plan with acceptable limits of precision.