The influence of varietal differences in plants on infestation by aphids has received considerable attention in control studies. Painter (14), in 1941, concluded that the composition of the available food in the host plant plays possibly the most important role in determining the relative resistance to aphid attacks. In biological studies on Aphis rumicis L., Davidson (8) found that factors that influence the physiological activity of the plant affect also the progress of aphid infestation. The same author (6) also pointed out that aphids exhibit a wide range of fecundity on different hosts. “The sap of certain varieties of beans”, writes Davidson, “appears to have a direct inhibiting effect upon the reproductive capacity of the aphids, whereas that of other varieties seems to have the opposite effect.”

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.

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.

Although there is a great deal of literature on the relative potencies of many insecticides to various insects and although many histological and physiological studies of insects have been made, observations on tissue changes in insects caused either directly or indirectly by insecticides have been few (Pilat, 1935 and Hartzell, 1945). Such observations are important in advancing our knowledge of specialized insect histology and, therefore, of insect physiology. They are of further value because they provide indications of the mode of action of insecticides on insects, a knowledge which is of great importance not only in the development of exact as opposed to indiscriminate methods of application, but also in the development of new and more specific insecticides.