The philosophy of subspeciation among animals requires that these taxa be essentially reproductively isolated. When such isolation does not exist clines appear. We believe that we have discovered one of the rare occasions when two well-defined subspecies, considered by some taxonomists to be two species, occupy the same terrain and where some degree of hybridization has taken place with the production of a hybrid brood that is temporally isolated from one subspecies and geographically from the other. Neither isolation may be absolute but that condition is closely approached.

Two species of moths are known to kill shoots of larch (Larix) by mining them: Argyresthia laricella Kearfott in Canada and A. laevigatella Herrick-Schäffer in Europe. The biology and economic status of these insects are compared by Eidt and Sippell (1961).

Opinions differ as to whether the Argyresthia on larch in Europe are one, two, or three species (Edwards, 1911; Grosvenor, 1911; Adkin, 1918). Beirne (1942) believes that only one species is involved but Kratochvil (1943), who did not know of Beirne's work, recognized two species. A. atmoriella Bankes in England and Silesia; A. laevigatella in central Europe. I have referred to all European material as A. laevigatella.

Most of the relative humidity gradients used in ethological studies of insects are of the alternative type in which a choice between only two relative humidities is possible (Perttunen, 1953; Wigglesworth, 1941). Sometimes, during investigations of behaviour and distribution of insects, it may be desirable to know the humidity preferred when insects are exposed to an environment in which a number of different humidities prevail in a definite, specified range. In some cases both the range of humidities in a gradient and the values of the extreme humidities apparently affect the preference exhibited by certain arthropods (Perttunen, 1953; Bursell and Ewer, 1950; Lees, 1943). The circular apparatus described here allows the simultaneous production of two identical gradients, one in each half of the circle.

In subarctic Canada conventional methods of correlation and regression analyses were inadequate in relating periodicities in mosquito flight to fluctuating physical environments (Haufe, 1958). The periodicity for individual species shifted in relation to sidereal time. In addition to a random component in the variation, a gradual shift was associated with the advance of the season for consecutive cycles of activity. For the most abundant species it appeared as older individuals constituted an increasing proportion of the natural populations. The relative variations in absolute values of light and hygrothermal conditions identified with 24-hour flight periodicities were inconsistent with seasonal variations in 24-hour meteorological cycles. If light was a primary factor in the activation of natural populations in the 24-hour cycles, observed variations in correlations would suggest variable adaptation of mosquitoes to previous light conditions and to other physical and biological factors.

The European pine shoot moth, Rhyacionia buoliana (Schiff.), has been recognized as a pest of pine plantations since it was described in 1776. Neugebauer (1952) stated that 32 susceptible pine species were known and that scarcely any species were rejected by the insect. Following its accidental introduction into North America about 50 years ago (Busck, 1914) the shoot moth became a serious pest of red pine, Pinus resinosa Ait., which appears to be the most susceptible species (Heikkenen and Miller, 1959). Watson (1947) described the shoot moth as “the most destructive insect affecting hard pines in southern Ontario, and the most difficult to control”. Plantations have been damaged so severely that the planting of red pine has been virtually discontinued within the pest's range.

Elsewhere (Scudder, 1957a), I have outlined briefly a revised interpretation of some basal structures in the insect ovipositor. It was shown that in insects other than the Machilidae, the female genitalia has a common plan, this plan differing from that usually taken as the basic type. Whilst Snodgrass (1933) based his interpretations of all the higher orders on the condition in Machilidae, I have shown that a more satisfactory interpretation is obtained if the condition in the tepismidae is taken as the basic tvpe.

The principal insects that attack toadflax (Linaria vulgaris Mill.) in Canada are Brachypterolus pulicarius (L.), a flower-eating nitidulid, and Gymnaetron antirrhini (Payk.), a seed-eating weevil. B. pulicarius was found in 1953 in all provinces of Canada but G. antirrhini was apparently absent from Saskatchewan and Alberta, the two provinces where the spread of toadflax was causing alarm. Thus the seriousness of the toadflax seemed to be related to the absence of G. antirrhini. In an artempt to correct this situation Smith (1959) collected 4,000 adult G. antirrhini and released them in mid-July, 1957, at Marsden, Saskatchewan, and Codesa, Alberta. However, it now appears that the rapid spread of toadflax occurred in the absence of B. pulicarius and that this beetle is more valuable than first thought. This paper discusses the role of B. pulicarius and the results of introducing G. antirrhini.

Spiders of the genus Philodromus Walckenaer have the flattened body and laterigrade legs of all Thomisidae, or crab spiders, yet lack most of the specializations of the more typical genera in the family. The latter, which comprise the subfamily Thomisinae, are characterized by strong, heavy bodies, prominent eye tubercles, a marked disparity between the length of legs I and II as opposed to that of III and IV, rotund abdomens, and a slow gait (Gertsch, 1939). In Philodromus and throughout the Philodrominae we find a lithe, smooth body that is weakly spined and covered with soft, recumbent hair (Fig. 22). The legs are slender and nearly equal in lengh; These spiders typically lead an active, predatory life on surfaces and in crevices of woody plants. They are able to exploit this type of habitat largely because their legs are equipped with well-developed scopulae and claw tufts.

A low speed wind tunnel was needed for work by Dr. J. Juillet at the Belleville Institute to determine the number and direction of insect flights in a given time at different wind speeds and hence to determine the influence of wind on flight activity. This paper describes a tunnel designed to produce wind speeds of up to 9 miles per hour with uniformity within ± 5 per cent.

Nearly all forest regions in the Province of Quebec where balsam fir (Abies balsamea (L.) Mill.) is an important tree component have been subjected to severe defoliation by the spruce budworm, Choristoneura fumiferana (Clem.), during the past 20 years. These outbreaks have followed an easterly direction beginning near the Ontario-Quebec border in 1939 and ending in the Gaspé Peninsula in 1958.

In 1958, Pilophorus uhleri (Knight) (Hemiptera: Miridae), Vespula vulgaris (L.) and V. rufa consobrina (Sauss.) (Hymenoptera: Vespidae) were recorded for the first time as being not only active predators of Neodiprion swainei larvae, but also vectors of a virus disease affecting this sawfly (Smirnoff, 1959). The latter vespid was considered to be especially important. In the summer of 1959, in the same area (St. David de Falardeau, Lake St. John region, Que.), more insect species were identified, which preyed on the first- and second- instar larvae of N. swainei. Most active were Lasioglossum (Evylaeus) sp. (Hymenoptera: Halictidae) and Crabro sp. (Hymenoptera: Sphecidae), while three species of Vespula were also observed: V. maculata (L.), V. arenaria (Fab.) and V. norwegica norvegicoides (Slad.) (Figs. 1-4). This completes the list of insects which have been observed to prey on swainei larvae. Data were also obtained on the period of greatest activity of each of these predators.

Glypta fumifermae (Vier.) (Ichneumonidae) and Apanteles fumiferanae Vier. (Braconidae) are two of the most common parasites of immature larvae of the spruce budworm, Choristoneura fumiferana (Clem.). Females parasitize the minute host larvae in the fall. Their eggs or larvae lie dormant within the hibernating host larvae, and then resume development in the spring, when the spruce budworm larva breaks hibernation and commences to feed. The budworm host is killed by Apanteles usually when it is in the fifth larval instar or by the Glypta when it is in the sixth instar.

This study was originally undertaken so as to provide information on the life history and ecology of Tarsonemoides truncatus (Ewing), to describe for the first time the developmental instars and male, and to redescribe the female of this species. Research soon indicated, however, that a group of closely related species of mites, including T. truncatus, was involved and that the problems to be investigated were more complex and extensive than anticipated.

The genus Bolbomyia Loew, 1850, was erected on the basis of specimens in Austrian amber. No specific name was applied to the material. Bolbomyia nana Loew was described in 1862 from a single female collected at Washington, D.C., U.S.A. The species has since been redescribed twice, as Misgomyia obscura by Coquillett, and as Ptiolina mitis by Curran, on the basis of eastern North American material.

A second species has recently been collected in western North America, and it is the purpose of this paper to describe this new species and redescribe the genus.

Prosimulium fuscum Syme and Davies, P. mixtum S. and D. and P. fontanum S. and D. form a complex of closely-related and largely sympatric species formerly known in North America (Twinn, 1936; Stone and Jamnback, 1955) under the single name P. hirtipes Fries, a well known species in the northern Palaearctic. The first step in demonstrating the multiple nature of the forms grouped under this name in North America was taken by Rothfels (1956) who showed by study of rhe larval salivary gland chromosomes that at least three non-interbreeding forms were present in eastern Canada. L. Davies (1957a) concluded from a study of specimens of all life-stages that none of the North American forms agreed with European P. hirtipes. A further step in the process was afforded by the work of Syme and D. M. Davies (1958), which erected the three species named above as a result of anatomical study of cytologically defined material, and showed that adult females of P. fuscum and P. mixtum could be reliably separated, mainly by features of the genitalia. The present work may be considered as a further step in the study of the common Prosimulium of eastern North America, by providing information on their ecology, thus amplifying the cytological and anatomical conclusions arrived at in the papers cited above.

In the spring of 1959, Dr. O. Peck of the Entomology Research Institute, Department of Agriculture, Ottawa, Canada, sent to me a long series of Eurytoma specimens for determination. Dr. J. B. Thomas reared the series from buds of jack pine (Pinus banksiana) and is ready to publish on the biology of the species. This new species has been included in a projected revision of the genus Eurytoma in North America, north of Mexico, but due to the uncertainty as to just when it will be ready for publication, it seems best to publish the description concurrently with the paper by Dr. Thomas, so as not to hold up 'his valuable contribution to the biology of the species.

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.

During a study of the parasites attacking the forest tent caterpillar, Malacosoma disstria Hbn., a ready means of identifying puparia of the common dipterous parasites proved necessary so that those individuals that failed to develop beyond the puparial stage in laboratory rearings might be identified in advance of lengthy cold treatment and incubation. The following key was therefore developed on the basis of the study of series of puparia associated with adults determined by the Entomology Research Institute. The key includes the ten most common dipterous parasites of the tent caterpillar in Ontario, seven of which have been included in a similar key to the parasites of Malacosoma spp. in British Columbia (Ross 1953). The terminology used in these two keys is similar, and is adapted from Green (1921).

It is well known that living plants possess electrical potentials and radiate electrostatic fields (Lund, 1929a, 1929b; Rurr, 1945; Dewey, 1956; Maund and Chalmers, 1960). Additional charges are added to the plants by raindrops and by splashings from soil, dust, and insecticidal sprays. The following is a report on experiments to show whether charged surfaces influence insect movements.

This paper describes a new species of the genus Dasiops Rondani, which is known to be a primary pest of apricot fruits in California (Moffitt and Yaruss, 1961). In common with other Lonchaeidae, the adult of this species is small (about three mm. long) and rather stout; with a shining, metallic blue-black body; the female possesses a long, piercer-wpe ovipositor (Figs. 5-7) similar to that of otitids and trypetids. Other characters that serve to distinguish the family include: black halteres, hairy frons which is narrower in the male than in the female (Figs. 1, 2), a single, reclinate upper frontal bristle, diverging postvertical bristles, a row of bristles near posterior nargin of the mesopleuron, one or more sternopleural bristles and (usually) bare ptero- and hypopleuron. The genus Dasiops can be distinguished from other genera of Lonchaeidae by the presence of tiny, forwardly directed poststigmatal bristles which arise in the depression above the mesothoracic spiracle just cephalad of the anterodorsal corner of the mesopleuron.