The research program of the Division of Entomology is steadily evolving as surely as are the insects themselves. The broad outlines of today's program have been shaped through the years by central administrative policies, by the nature and significance of the problems encountered, and by the pressure of public demand; the detail has been affected primarily by the availability of trained staff and research facilities, by the quality of local leadership, and by pertinent developments in sister sciences. All of these are continuing influences, which, together with important recent developments and some weighty unpredictables, will determine the nature and scope of tomorrow's program. But certain trends in research seem clear. The subject is discussed under three main headings, with a final summarizing statement.

Walker (1866) described Chauliodes disjunctus on the basis of a single female from Vancouver Island. Davis (1903) identified males and females from California as belonging to this species and noted that the male antennae were pilose and as long as the head and thorax combined. Supposing Davis' observation to have been based on a broken specimen, van der Weele (1910) referred C. disjunctus to Neohermes Banks, 1908, as a close ally and probable synonym of Neohermes californicus (Walker), a species in the male of which the antennae are as long as the body and are provided with segmental whorls of long hair.

A study of the insect inhabitants of the sour cherry orchards of the Niagara district of Ontario was begun in the spring of 1947, ass part of an investigation of virus diseases of stone fruits carried on cooperatively between the Dominion Entomological Laboratory at Vineland Station and the Dominion Laboratory of Plant Pathology at St. Catharines. The virus disease cherry yellows of sour cherry had by that time become prevalent and appeared to be spreading rapidly. The rate and pattern of spread revealed by a survey of orchards suggested that an insect vector may be involved in the dissemination of the virus. The Hemiptera were chosen as the first group for study because most of the known vectors of plant viruses belong to this order.

It is well known that no living organism can continue to multiply indefinitely. Sooner or later environmental factors combine to slow down the rate of increase and eventually bring it to a halt. This is the phenomenon we call “natural control”. Among the environmental factors responsible for the natural control of insect pests, parasitic and predacious insects sometimes play an important part.

During the latter part of August and early in September, 1950, dolichopodid flies were observed feeding on adults of the European red mite on apple foliage, untreated with acaricides, in the Science Service orchard, Harrow, Ontario.

Specimens were determined by Mr. J. R. Vockeroth, Systematic Entomology, Division of Entomology, Ottawa, as follows: Condylostylus sipho (Say), Laxina nigrofemoratus (Wlk.), and Diaphorus or Chrysotus sp.

In many parts of the St. Lawrence drainage system, enormous numbers of Trichoptera, often mingled with Ephemerida, emerge during the summer and become a pest in a considerable zone bordering the water. The insects swarm in open areas, especially around trees and lights, invade houses, settle in large numbers on walls and other surfaces, ruining those that have been freshly painted, and pile in decaying and odoriferous drifts along the shore line. In addition, they give rise to a medical problem by evoking allergic reactions in hypersensitive individuals.

The parasitism of the yellow-headed spruce sawfly, Pikonema alaskensis (Roh.), was studied in the course of investigations on the control of the sawfly in farm shelter-belts. Although some of the chemical control measures used against the sawfly destroyed its parasites, others did not. A knowledge of the parasites and their abundance in the study area became necessary. Since most of the parasites known to attack the sawfly emerge from the cocoons, this stage of the host was investigated first.

During the year 1950 I enjoyed the opportunity of examining the collections of Odonata made by the Northern Insect Survey, a co-operative project of the Canadian Department of Agriculture and the Canadian Department of National Defence. For this privilege I wish to express my thanks to Dr. G. P. Holland and the members of his sraff in the Systematics Unit of the Division of Entomology, particularly to Dr. T. N. Freeman, co-ordinator of the Survev, and Mr. W. A. Brown for “their kindness in providing laboratory facilities during visits to Ottawa and for shipping material to Toronto.

Swaine and Craighead (1924) have presented evidence that outbreaks of the spruce budworm occurred in Eastern Canada in 1806 and in 1878. In those days the wood supply appeared to be unlimited and the forest represented, to some extent, an obstacle that had to be removed so that the land could be cultivated. Balsam fir, the tree principally affected by the budworm, was seldom used for lumber when spruce was available. It can hardly be considered, therefore, that these early outbreaks caused much direct economic loss. If the trees had not been killed by the budworm, over-maturity and related factors would have removed them to make way for a new stand. In fact, were it not for the undesirable effects of budworm outbreaks on subsequent forest composition, it might even be argued that they were beneficial under certain conditions.

Studies on the transmission of the virus of little cherry disease in the Kootenay Valley of British Columbia involve the feeding of introduced insects on uninfected cherry trees. Muslin cages slipped over individual branches and tied at both ends were first used to confine the introduced insects but resulted in heavy insect losses. Temperature within the caged area was likely to be excessive, it was difficult to introduce and recover the insects, and insects became entangled in the muslin. A special cage has been designed to overcome these difficulties.

In the course of studies on the insects associated with the Dutch elm disease, several larvae and adults of a cerambycid beetle, Physocnemum brevilineum (Say) were encountered in the bark of both living and recently dead American elm trees. This species is generally recorded as an inhabitant of the outer bark of living elms. Observations show that injury to the living inner bark is rather common, and that occasionally patches of the cambium may be killed. In felled logs, larval behaviour is atypical.

The lodgepole needle miner, Recurvaria milleri Busck, was discovered in 1903 in the Yosemite National Park, California, and was described as a new species by Busck (1914). The infestation has persisted in that area, with irregular periods of abundance and scarcity. The latest heavy infestation was reported (G. R. Struble, in litt.) to have started in 1947, and has continued to intensify. The history of the outbreak to 1919 was reported by Patterson (1921).

In 1942 a second important infestation was reported in the Banff National Park, Alberta. Details concerning the area of infestation and life-history notes were given by Hopping (1946). This infestation has continued to spread and has reached Yoho, Kootenay, and Revelstoke National parks.

During the course of an investigation of the dispersal of the spruce budwonm (Henson, 1950), mass flights of the insect have been studied. The records of these flights are to be found in the files of the Forest Insect Laboratory, Sault Ste. Marie, Ontario, but in many cases these records are not complete. Nineteen flights for which sufficient data exist have been examined.

In connection with an attempt at the biological control of the weed Cordia macrostachya in Mauritius (see Simmonds 1948) information was required as to the effect on the plant of periodic defoliation similar to that caused by leaf-eating beetles, two species of which showed promise for introduction from the West Indies against the weed. In spite of the obvious general importance of the effect that defoliation by insects has on plants very little work has been done to determine in any particular case the manner in which a plant reacts to damage of this nature. With Cordia it was particularly important to ascertain what effect, if any, defoliation has on inflorescence and seed production.

Several ecological factors governing populations of the larch sawfly, Pristiphora erichsonii (Htg.), have been studied in Manitoba and Saskatchewan since the present outbreak began about 1939. It soon became clear that soil moisture, parasires and predators, and the growth habits of tamarack were among the most important components of the environmental resistance. Data from ohservations and experiments were gathered by several investigators of the Forest Insect Laboratory, Winnipeg. Manitoba, and are still largely unpublished. In this paper, an attempt is made to appraise the over-all effect of these factors on abundance of the larch sawfly.

As the flea fauna of mammals of northern North America becomes better known, its very close affinity with that of temperate and northern Asia becomes more apparent. Many of the genera are holarctic and are associated with holarctic genera of mammals. In a few instances, the fleas of the Old World and the New World are so similar in morphological details and host association that they are regarded as subspecies. For example, Amphipsylla sibirica (Wagner), Malaraeus penicilliger (Grube), Megabothris calcarifer (Wagner), and Hoplopsyllus glacialis (Taschenberg) have representatives in both the nearctic and the palaearctic regions. To this list must now be added Catallagia dacenkoi Ioff, a parasite of Microtinae; this species was described originally (Ioff, 1940, pp. 216-217) from the Altai Mountains of central Russia, and a new subspecies has now been discovered in northern Canada and Alaska.

Several blow fly collections were made in the vicinity of Fairbanks between May 28 and June 14, 1948, and one large collection at Anchorage on August 9, 1948. All flies were caught in screen-wire fly traps baited with liver or dead salmon. The material was identified by D. G. Hall, Bureau of Entomology and Plant Quarantine, who also generously provided information concerning the possible importance of the various species of Alaskan blow flies.

In 1945 injury to shoots of balsam fir, Abies balsamea (L.) Mill., by sawfly larvae was very common in York and Madawaska counties, New Brunswick. Since then, similar injury has been noticed throughout most of New Brunswick, eastern Nova Scotia, the upper peninsula of Michigan and northern Wisconsin.

New Brunswick specimens were identified by Dr. O. Peck of the Systematic Unit, Division of Entomology, as presumably Pleroneura borealis Felt, the specimens running to this species in Ross' Key (2); however, as stated by Ross (3), the recognition of species in the genus is not at present based upon fundamental characters. P. borealis was originally described in 1917 by Felt (1) from three specimens collected at Lake Clear, N.Y., in 1907. Except for the taxonomic revision by Ross (2), no other reference to this species was found in the literature.