It is a well known fact, noticed by many workers engaged in breeding hymenopterous parasites, that there is a tendency in many bisexual species for the sex-ratio to decrease as the breeding work proceeds over a series of generations. In a number of cases the sex-ratio decreases to an extent where only males are produced, and the stock dies out.

In March, 1946, the writers reported in Scientific Agriculture (1) that benzene hexachloride showed pronounced fumigant action and that air currents as slow as 2 m.p.h. lowered its effectiveness against insects to a marked extent. The present paper deals with further experiments with benzene hexachloride and gives preliminary data on the fumigant action and effect of air currents on three other chlorinated hydrocarbons, viz., DDT, Hercules Toxicant 3956 (a chlorinated terpene) and Velsicol 1068 (a mixture of isomers with the empirical formul C10 H6 Cl8).

Rohwer established the genus Argorytes in 1912 for the reception of Fox's curious, stocky, little southern Californian species Gorytes Coquillettii. In the course of the ensuing thirty-five years, no subsequent investigator has recognized or admitted the validity of Rohwer's distinctive genus. In all probability, however, this is due largely to the relative rarity of the component species. In the past decade I have seen or assembled a number of specimens of this interesting genus and present below a revision of Arigorytes.

For a long time, the order Orthoptera was a loosely interpreted group which has now been restricted to more homogeneous forms. The well known cockroaches which formed the family Blattidae are now considered as a séparate order under the name of Blattaria.

The cockroaches are so well known that there is no need for a detailed description of their morphology. They are easily separated from the other insects by their soft bodies, by their oval and flattened form; the antennae are often longer than the body and are composed of many short segments; the head when at rest, is bent under and almost concealed by the pronotum, so that the mouth projects back to the base of the front legs.

The structure of the proventriculus of a ground beetle of the genus Chlaenius is described. It is similar to the proventriculi of ground bettles studied by other authors, in that its sclerotized intima is organized in the form of four longitudinal folds alternating with four longitudinal ridges.