Field observations on the beet leafhopper, Eutettix tenellus, in California

Abstract does not appear. First page follows. During 1918-1932 field investigations were carried on to determine where the beet leafhopper spends the winter and to locate the natural breeding areas in this state. Trips were taken to Death Valley, Mojave Desert, Imperial Valley, and the Tulare Lake and Bakersfieid sections of the San Joaquin Valley—areas from which Ball(2) believed the beet leafhopper migrated into sugar-beet fields—and also to the middle and northern sections of the San Joaquin Valley, to the Sacramento Valley, Santa Clara, and Salinas valleys, and to all other important sugar-beet districts in California. After a general survey of this enormous territory, it soon became evident that it would require many years of field work to map the natural breeding areas of this insect, and hence the work was limited to the San Joaquin, Sacramento, Santa Clara, and Salinas valleys and to several small valleys. No foothill investigation has been carried on in Death Valley, Antelope Valley, Mojave Desert, and Imperial Valley. Such results as were obtained in these districts have been published in previous papers.(28), (30), (40) The host plants of the beet leafhopper on the uncultivated plains and foothills, in the cultivated areas, and the original native host plants, the spring and summer dispersals and migrations, natural barriers, causes of fluctuation in population, and natural enemies were also observed during the investigations. Distribution of Beet Leafhopper The beet leafhopper is a native species and has been taken in western North America from Canada into Mexico. Davis(11) found the northern limit of the leafhopper was Cache Creek, British Columbia, 140 miles north of the international boundary. Carter(10) used the climograph as a means of comparing climates with respect to precipitation and temperatures in determining the probable limits of the range of the beet leafhopper; these studies were supplemented with surveys of the distribution of the insect. He considers that the presence of the leafhopper in British Columbia is due to a northward migration. Carter(9) published the results of the Canadian survey conducted by H. L. Seamans and states that the leafhopper was not found in the province of Alberta, although the results of the survey were not conclusive. Davis(11) found that the leafhopper was generally distributed in western Washington and Oregon.