The transmission of nuclear polyhedrosis virus in populations of the forest tent caterpillar, Malacosoma disstria (Hübner), was studied in Sudbury district, Ontario. Virus was transmitted from generation to generation by infected adults. Their progeny died from virus disease during the second and third larval instars. Adult flies of Sarcophaga aldrichi Parker, a dipterous parasite, were attracted to these dead, diseased larvae, became contaminated with virus, and spread the virus to foliage on which healthy larvae were feeding. The importance of these disseminating agents in the development of virus epizootics is discussed.

The known distribution of Thymelicus lineola (Ochs.) now includes large areas in Ontario. Spot infestations are recorded from such widely separated areas as Lanoraie and Montreal, Quebec; Ottawa, Sault Ste. Marie, and Fort William, Ontario; and Terrace, British Columbia.

Infestations of T. lineola can be reduced by cutting infested areas during June, before adults emerge, or by spraying with Thuricide 90T at the rate of 2 pints per acre. The biology of the European parasite Stenichneumon scutellator Grav. is being studied prior to possible release.

A detailed description of the larva of Melanophila acuminata DeGeer is given with some distinctive characters of the larva of M. fulvoguttata (Harris). A list of the host plants is also given for both species.

In the Niagara Peninsula, Ontario, leaf galls produced by fundatrices of the grape phylloxera, Phylloxera vitifoliae (Fitch), first appear soon after the beginning of shoot growth. The infestation builds up later as the result of almost continuous gall formation by at least four overlapping generations of gallicolae, until at the end of the growing season galls may be up to 2000 times more numerous than in the fundatrix generation. A portion of the first-instar crawlers hatched in leaf galls migrate, fall, or are blown from the foliage to the soil, beginning when second-generation gallicolae hatch, and reaching a maximum late in August, probably after the fourth-generation gallicolae begin to hatch.

Five Cretaceous fossil aphids from Canadian amber are described. All are new species and none is referable to an extant genus. The names assigned to these are as follows: Palaeoaphis archimedia, Ambaraphis costalis, Alloambria caudata, Pseudambria longirostris and Aniferella bostoni. Two new subfamilies have been proposed for four of them and the fifth has been placed in the Neophyllaphidinae, which was previously considered a tribe in the Callaphidinae. One new subfamily, the Palaeoaphidinae, is exceptionally primitive and the two included species, P. archimedia and A. costalis, have more antennal segments and a more primitive wing venation than any known aphid. The cubitus vein in these species is more like that of the Psyllidae and of the extinct Permian Archescytinidae than that of existing Aphidoidea. The venation of the other new subfamily, the Canadaphidinae, shares some similarities with the unipterine aphids that occur on the Combretaceae in Africa.

The main features of the evolution of the aphid wing are discussed as an aid in placing the fossils with respect to current concepts of aphid classification.

Pithanus maerkeli (H.-S.) and Actitocoris signatus Reut. are Holarctic in distribution, and the latter is recorded for the first time from North America.

The behaviour of Dendroctonus pseudotsugae Hopk. in different physiological states was studied in relation to temperature, light, and host.

Newly emerged beetles preferred temperatures near the threshold for flight. When conditioned in dry air at room temperature for 16 hours they preferred cooler temperatures.

At room temperature, most newly emerged beetles settled in the brightest zone of a light gradient (55 foot-candles), although some settled in dimmer zones. If the beetles' emergence was delayed or if they were stored after emergence, more remained in the zone between 0.5 and 10 foot-candles.

In light-dark tests at room temperature most newly emerged beetles were photopositive, but some were indifferent and a few were photonegative. Increasing the temperature and humidity increased the proportion of photonegative individuals. Newly emerged females oriented more directly to a single source of light than males, bur after conditioning or aging both reacted similarly.

Females were separated into three behavioural types based on their reactions. Photopositive individuals flew more readily than indifferent or photonegative beetles; some photonegative females showed no inclination to fly.

Photopositive females were usually host negative but photonegative females were host positive. The proportion of these behavioural types within different samples varied. A group that emerged early contained a higher incidence of photopositive host-negative individuals than a group that emerged late, or was stored for 10 days after emergence. But host-negative beetles would attack logs after starvation, flight exercise, or exposure to more attractive hosts.

Host-positive females contained less fat than host-negative siblings. The decline in lipids during aging, starvation or flight thus may induce behavioural changes.

There is a co-ordination of successive activities in the Douglas-fir beetle similar to that reported for aphids. The initial urge to disperse outweighs responses to host stimuli, but this balance changes as the beetles fly or as host stimuli increase. The balance between thresholds for dispersal and attack also varies in relation to the conditions under which the emerging beetles developed. Consequently, each individual behaves differently when it emerges. The behaviour of a population changes as the season progresses and from year to year owing to changes in the state of individuals and in the attractiveness of hosts.

Interspecific pairing of closely related species of Ips and Orthotomicus was undertaken to test their degree of breeding isolation. Pairings of the following species frequently resulted in sperm transfer but no eclosion: Ips mexicanus × I. concinnus (group I), confusus × montanus (group IX), plastographus (group III) × pini (group IV) and Orthotomicus latidens × O. sabinianae.

Mating was generally unsuccessful when the more distantly related species, confusus × plastographus and confusus × pini, were paired.

Individuals which produce all-female broods were discovered in a population of O. latidens. About 50% of the eggs deposited by these females hatched, whereas 92% of the eggs from “normal” females produced larvae.

Cytological investigations revealed no constant differences between the karyotypes of I. mexicanus and concinnus (7AA+Xyp), O. latidens and sabinianae (9AA+Xyp), or between I. confusus and montanus (15AA+Xyp). I. pini (oregonis) and plastographus also have karyotypic formulae of 15AA+Xyp, but both are easily distinguished from confusus and montanus and an atypical chromosome in pini (oregonis) distinguishes it from plastographus. The mexicanus and concinnus karyotype and that of O. latidens and sabinianae can be directly derived from each other by fusion or fission. Their relationship to the karyotype of the European species O. proximus (6AA+Xy), is plausible but their karyotypes are composed of a remarkably different number of autosomal arms from those known for other species of Ips.

Pseudopterocomma canadensis, Chaitophorus nudus and Chaitophorus nodulosus are described as new. All three infest species of poplar in North America. The affinities of each are discussed.

In Ontario, pear has been the only recorded host of the pear psylla, Psylla pyricola Foerster (Goble 1963), although in other areas of the world Quince, Downy Chess Grass, and apple twigs have also been reported (Smith 1941; Swirski 1954; and Wilde 1963).

Numbers of pear psylla adults were observed on climbing night-shade, Solanum dulcamara L. (Muenscher 1955) growing as cover crop in a pear orchard near Paris, Ontario, in 1965. Regular observation of psylla occurrence on this plant host throughout the growing season indicated that P. pyricola Foer. could complete its life cycle on S. dulcamara; eggs and nymphal stages up to the hard-shell stage, as well as cast nymphal skins, were observed on this host. Egg mortality was noted on those portions of S. dulcamara that were damaged showed severe wilting characteristics. Egg and second-instar nymph on the undersurface of the leaf of S. dulcamara are illustrated in Figs. 1 and 2.

Species and subspecies described as new are Chrysomelinae: Cbrysomela sonorae from Arizona and Mexico; Curculionidae: Anthonomus (Coccotorus) pumilae pumilae from Ontario, A. (C.) pumilae major from Manitoba, Conotrachelus corni from Ontario and Manitoba, and Hexarthrum thujae from British Columbia. Diorymerelhis Champion 1908 is synonymized with Stethobaris LeConte 1876; the genus evidently depends on orchids. A key to all species of Coccotorus is offered. The occurrence of local races in Chrysolina subsulcata (Mann.) and C. magniceps (J. Shalb.) is noted.

Newly hatched larvae of Oryzaephilus surinamensis (L.) developed quickest on untreated flour plus 3% of wheat germ, but survived best on commercial vitamin-enriched flour. They developed as quickly on a synthetic casein diet containing 1.25 γ of biotin per gram as on vitamin-enriched flour, and survived as well on the synthetic casein diet as on untreated flour plus 3% of wheat germ. They developed slower and survived less well on a synthetic casein diet containing biotin at a concentration of 7.50 γ per gram than on untreated flour plus 3% of wheat germ. They also developed slower and survived less well on a casein diet containing ascorbic acid at a concentration of 0.025 g. per gram than on untreated flour plus 3% of wheat germ. Adults did not always emerge in the shortest time on diets on which the larvae pupated most quickly.

Three species of aphids in the subfamily Eriosomatinae are recorded from poplar trees in southern Alberta. Asiphum sacculi Gillette caused galls on leaves of Populus tremuloides Michaux in the foothill and mountain areas. Thecabius populiconduplifolius Cowen caused galls on leaves of Populus balsamifera L. in the prairie area. Pemphigus bursarius L., the lettuce root aphid, caused galls on leaves of Populus nigra var. italica Meunchhausen in a garden. P. bursarius could become a pest of lettuce in southern Alberta.

Porcupinychus abutiloni, a new genus and species of mite, commonly found on Abutilon indicum in the Karachi area of West Pakistan, is described and illustrated.

Based on evidence from the structure of the male genitalia, the caddisfly genus Mystacides Berthold has evolved into four distinctive monophyletic clusters of species, the primitive longicornis group and the more specialized indica, azurea, and sepulchralis groups. When geographic range is plotted against phylogeny, the genus appears to have originated and proliferated chiefly in Eurasia, but with two fairly recent dispersals into North America. M. sandersoni (Malaya) and elongata (China) are described as new, and M. interjecta Banks is resurrected for previous records of American longicornis auct. nec. Linnaeus. M. longicornis (L.) is entirely palearctic. M. sibiricus Martynov is a new synonym of interjecta (Banks).

Metanopedias sicarius Brues, 1910 is considered a new synonym of Trichacis brunneipes Ashmead, 1887. The genus Metanopedias Brues is redefined and Metanopedias brunneipes (Ashmead) new combination is proposed. The latter species is redescribed and illustrated, its geographical distribution and host relationships are listed and discussed.

Thymelicus lineola, a univoltine grass-eating skipper introduced into southern Ontario from the Palearctic prior to 1910, is spreading rapidly and extensively in North America, moving outward in all directions from its origin. Its present distribution (doubtless inadequately known) includes parts of Michigan, Ohio, New York, Pennsylvania, Maryland, New Jersey, and Connecticut; Edmundston, New Brunswick; all of southern Ontario northeast to Ottawa, plus Sudbury, Sault Ste. Marie, and Fort William; and Terrace, British Columbia. (The last record may stem from an independent introduction from Eurasia.) Dispersal and colonization are probably much aided (unwittingly) by man. Range expansion often seems to involve a sequence of events (associated with founding of initially small colonies that rather quickly reach high population densities) that may promote rapid evolutionary differentiation of populations.

Mosquito-repellent chemicals tend to absorb far infrared radiation (below 600 cm.−1) more strongly than do non-repellents of comparable molecular weight. The correlation is probably less direct than was previously supposed, and is hardly strong enough to be used as a primary screening technique.

The pH changes occurring in different rearing media, both with and without housefly larvae (Musca domestica L.), were evaluated. In standard medium which consisted of non-fat milk, brewer's yeast, liver, agar, and water, the pH surrounding the eggs and first-stage larvae was about 5.6. As the larvae grew and agitated the medium, at 5 mm. depth the pH increased and by 72 hours read about 7.5. This 7.5 was significantly higher than the pH 5.0 recorded at the same depth and time in the standard medium without larvae.

A three-year study on the seasonal occurrence of ground beetles was conducted in five fields with different crop rotations. More than 10,000 individuals representing 102 species were captured in pitfall traps. The relatively high total number of species collected the first year probably resulted from the particular location of the traps along field margins and close to woodlands. The variation observed between the areas studied was not necessarily related to the kind of crop. A progressive augmentation in beetle activity and population appeared to coincide with an increase in the humidity of the habitats and with the cultures in the following order: pasture grass, forage, cultivated, and cereal crops. This indicates that the nature of the crop influences beetle numbers, and from this it may he inferred that it also influences the extent to which the beetles exert a control influence on pest species. Of the eight species present every year and found in practically every field, Pterostichus melanarius Ill., Harpalus pennsylvanicus DeG., and H. compar Lec. were the most numerous.