Bionomics of the walnut husk fly, Rhagoletis completa

does not appear. First page follows. The persian walnut (Juglans regia) industry of the United States is centered in the state of California, where approximately 97 per cent of the tonnage is produced.(4) Batchelor(4) estimates that the bearing acreage for 1930 was 95,900 acres, with an expected increase of approximately 6,000 acres a year for the next three years. Concerning the economics of the industry he states, “Pest control is becoming an increasingly costly operation in some localities, and this is causing the replanting of former walnut acreage to crops not subject to the pests in question.” The recorded insect fauna(3) of the genus Juglans numbers over 300 species, only a small number of which occur in California. Before the advent of the walnut husk fly, Rhagoletis completa Cresson, the codling moth, Carpocapsa pomonella (Linn.), and the walnut aphid, Chromaphis juglandicola (Kalt.) were the only species considered to be of major importance to the industry. With the addition of another major pest, the production costs will necessarily be increased in those localities where susceptible varieties are grown. It is of interest to note that Rhagoletis completa is the first species of Trypetidae of major economic importance to become established in California.