A symposium covering the general subject of insects in relation to plant diseases was held during the fiftieth annual meeting of the American Association of Economic Entomologists. Excellent papers were presented by Granovsky (1938), Kunkel (1938), Leach (1938), Poos (1938), and Stevens (1938). Another review of this fascinating field of research is not the intent of the present paper, which deals instead with insect vectors of plant viruses in relation to certain phases of plant quarantine.