STUDIES ON CONTACT INSECTICIDES: PART I. INTRODUCTION AND METHODS. PART II. A QUANTITATIVE EXAMINATION OF THE TOXICITY OF TEPHROSIA VOGELII HOOK. TO APHIS RUMICIS L. (THE BEAN APHIS).

Abstract

SUMMARY.1. The first part of this paper forms a general introduction to investigations carried out on contact insecticides. The methods used are briefly described and some consideration is given to the mode of expressing results.2. The second part deals in detail with the insecticidal properties of Tephrosia Vogelii Hook. which, with other species of this genus, occurs abundantly in many parts of the world. The aqueous and alcoholic extracts of the leaves and seeds of T. Vogelii are shown to be highly toxic to Aphis rumicis L., the toxicity being of the same order as that of nicotine. Extracts of the stems have not proved so poisonous.3. The plants of the genus Tephrosia seem to offer possibilities for practical use as insecticides and it is hoped to extend the work in this direction.