Escherich (7) was the first to report a polyhedral virus disease affecting the European pine sawfly, Neodiprion sertifer (Geoffr.). Later Forsslund (8) observed that populations of this insect in Sweden were controlled by a virus disease. In 1948, H. S. Hanson. Entomologist of the Forestry Commission, England, observed mortality among N. sertifer in England which was due to a polyhedral virus disease (10). In 1949 virus-killed larvae collected in Sweden by Forsslund, were sent to the Laboratory of Insect Pathology, Sault Ste. Marie by G. R. Wyatt of this laboratory and the virus from these insects was propagated and used in the biological control of N. sertifer in southern Ontario (3, 5). This paper describes some aspects of the laboratory studies of the disease, namely: the infection process in cells susceptible to the virus, incubation period of the disease, and the isolation and electron microscope study of the causal agent.

The European pine sawfly, Neodiprion sertifer (Geoffr.), is a serious defoliator of pine in many parts of Europe and Asia. Infestations of this insect have been controlled by weather, and frequently high percentages are destroyed by parasitic and predacinus insects, by small mammals, and by birds. Infectious diseases are most frequently reported as having controlled outbreaks, namely: virus disease (4, 5), bacterial disease (12). fungus disease (8), bacterial and fungus diseases (7, 11), a disease not diagnosed (9).

When spruce budworm larvae emerge in the spring, they either mine the needles of old foliage or feed upon the freshly opened staminate flowers of balsam fir. As soon as the vegetative buds begin to expand, the larvae abandon the needle mines for this newer and more succulent growth. Later, when the pollen is shed, the staminate flowers are in turn abandoned in favour of new shoots. Usually, the larvae continue to feed on the new shoots until pupation. When this insect reaches epidemic proportions, however, the current year's growth is often totally destroyed prior to the completion of the larval stage. Late spring frosts have also been known to destroy, in part, or even completely, the shoots of the current year's growth. Under these conditions spruce budworm larvae must resort to feeding on old foliage.

Depuis la découverte du pouvoir insecticide du DDT, des recherches intensives ont été faites sur d'autres composés synthétisés à partir de la charpente squelettique du DDT, à savoir le 1,1-diphényléthane:

De ces composés analogues au DDT, certains montrent une valeur insecticide supérieure à celle du DDT; d'autres s'avèrent inférieurs. du moins dans les conditions expérimentales que nous avons choisies. Nous présentons ici les résultats que nous avons obtenus dans nos expériences sur la toxicologie du dérivé cyanuré du DDT. Ce composé a été synthétisé pour la première fois par Perron (4,5) à l'Institut de Chimie de l'Université de Montréal. Nous avons utilisé la méthode mise au point par cet auteur pour préparer les quantités dont nous avions besoin pour notre travail.

That section of the genus Itame to which have been assigned the names argillacearia and occiduaria of Packard, modestaria and olivalis of Hulst and andersoni Swett has provoked many a sigh of exasperation among collectors and systematists trying to organize their material. The present paper represents several years of intermittent study and observation, and although no drastic changes in nomenclature or arrangement seem warranted, I shall set forth my conclusions for what they are worth. This may actually be regarded as a supplement to Dr. J. McDunnough's remarks on the group in a paper of 1924 (Notes on the Ribearia Group of the Genus Itame. Can. Ent., Vol. 56, p. 271), additional material having been examined that was not available to him at that time.

It is unfortunate that Frick (1952), in preparing his generic revision of the Agromyzidae, was unable to examine the types of many species described by Loew, Malloch, Frost, and others. In such circumstances, a few mistakes were bound to be made, and the fact that these are not more plentiful is a tribute both to the quality of the descriptions of the authors concerned, especially Malloch, and to the care with which these descriptions have been analysed. In 1949, being interested in the possibility of using Hendel's (1931) European classification for the North American fauna, I examined 71 of the types in question, and was able without difficulty to reconcile most of them wiih Hendel's generic and subgeneric concepts. Of these types, only 13 are now found to conflict with the assignment proposed for the species by Frick.

Many attempts have been made to overcome the difficulties attendant upon storing insect material over extended periods of time in small vials of alcohol. Cork stoppers fail to meet requirements for various reasons, while their substitution with rubber ones may introduce still further complications. Both are liable to shrink or to swell while either may be forced out of the vials as a result of variations in room temperature. In addition, neither can be readily marked in such a manner that the contents of the vials are permanently and plainly legible from above.

Studies on the ecology of the fauna of apple orchards in Nova Scotia were initiated in 1943, to determine the long-term influence of spray chemicals on the populations of apple-infesting insects. At that time it was felt that the indiscriminate use of spray chemicals in the control of orchard pests was sometimes creating worse problems than those corrected–and was threatening the economy of apple production; and that there was an urgent need to determine, if possible, how to harmonize biological and chemical control. A more comprehensive discussion on the biological and philosophical concepts on which the studies were based may be found elsewhere (Pickett et al., 1946; Pickett, 1949a; 1949b).