Periodic outbreaks of the large aspen tortrix, Choristoneura conflictana (Wlkr.) severely defoliate trembling aspen, Populus tremuloides Michx., in parts of Manitoba and Saskatchewan. The inadequacy of information on the insect prompted further investigation of its life history and the factors affecting its abundance. Field studies were conducted in Northern Manitoba and Saskatchewan, where from 1950 to 1954 the insect was found at various population levels.

During 1954, I had the opportunity of examining a large collection, circa 3,500 of unidentified Corixidae which had been accumulated in the Canadian Department of Agriculture over a period of years. These notes consist of a list of species identified, with observations where pertinent when these records are new state or country records compared with the full lists of localities given in H. B. Hungerford's ‘The Corixidae of the Western Hemisphere’ 1948, Univ. Kansas Sci. Bull. Vol. XXXII, pp. 1-827.

A study of 2,500 adults of the California five-spined engraver, Ips confusus (Lec.), has shown that the sex of this beetle can be determined from a secondary sex character with an accuracy exceeding 99 percent. Insects often have secondary characters that indicite sex, and in species with concealed genitalia, reliable secondary characters are especially useful for rapidly separating the males and females. Where such characters are lacking, a dependable determination of sex can only be made by the laborious procedure of dissection for a check of genitalia.

The extensive literature on the “lygus” bugs of economic importance in North America deals with members of the genus Liocoris Fieber (Kelton, 1955). In this paper four new species that formerly were misidentified as other species of the genus Lygus Hahn are described.

Among the many insects under investigation as potential vectors of the oak wilt fungus in Wisconsin and elsewhere, the species of Pseudopityophthorus have attracted considerable attention. Although recent developments appear to indicate that the long-distance spread of this serious disease occurs primarily with the aid of other insects, our knowledge at present does not warrant the assumption that bark beetles play no part whatever. In the study of P. minutissimus from August, 1952, to the fall of 1953, considerable information concerning its biology in Wisconsin has been brought to light; and regardless of its relationship to the oak wilt problem it seems desirable at this time to make better known this member of the Wisconsin bark beetle fauna.

From 1952 to 1955 the author has been engaged in a study of the predacious mites of importance in controlling the European red mite, Metatetranychus ulmi (Koch), in southern England. During this time an opportunity was afforded to become familiar with many of the species in the genus Typhlodromus that are thought to be of some value in this regard (Gilliart, 1935; Nesbirt, 1951; Collyer, 1953).

During an investigation into the importance of fungal disease as a factor in the control of orchard pests throughout the Annapolis Valley, Nova Scotia, the haemocoele of large numbers of Macrosiphum pisi (Kaltenbach) was found to be infected with a fungal growth that resulted in death. This fungus was identified from mounted specimens as Empusa (= Entomophthora) aphidis Hoffman.

Various authors have given general descriptions of the immature stages of various species of Stethorus, and Böving (1917) described certain morphological festures of the larvae of S. punctum (Leconte) and S. utilis (Horn), but no complete account of the morphology of these stages in any species of the genus has apparently been published. Clement (1880) gave the most thorough of the earlier descriptions of the immature stages of S. punctillum Weise.