Besides the synthetic organic insecticides we have discussed, others of less importance are in use. Still others are in the experimental and developmental stages. The wide variety of compounds that we have considered here gives evidence that the chemistry of synthetic organic insecticides covers the entire field of organic chemistry.

C. V. BOWEN, head chemist at the Orlando, Fla., laboratory of the division of insects affecting man and animals, Bureau of Entomology and Plant Quarantine, entered Government employ in 1923 in the Insecticide and Fungicide Board. He taught chemistry at Washington and Jefferson College from 1925 until 1937, when he returned to the division of insecticide investigations. His principal interest has been in research on the preparation, analysis, and formulation of synthetic organic insecticides.

S. A. HALL, a chemist, began analytical work with the Treasury Department in 1934 and in 1939 transferred to the Bureau of Agricultural and Industrial Chemistry to do research on naval stores. In 1943 he joined the division of insecticide investigations, Bureau of Entomology and Plant Quarantine, at Beltsville, Md., where he first worked on DDT and the development of insect repellents.

This cylindrical fungus-feeding beetle is admirably suited for living in round tunnels which it bores into forest trees for the propagation of its food.