Studies on the Distribution of the Pit Scale Aster olecanium minus on Oak Trees

Publisher： Entomological Society of America

ISSN： 1938-2901

Source： Annals of the Entomological Society of America, Vol.57, Iss.2, 1964-03, pp. : 146-150

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Abstract

Samples of branches were taken from various parts of valley oak (Quercus lobata Nee) trees in the central coast region of California during the dormant and growing seasons in 1962 for determination of numbers of Aster olecanium minus Lindinger (Homoptera: Asterolecaniidae). Scale density was found to decrease in a linear manner as height in the tree increased and as age of wood increased from 1 to 7 years. Densities were consistently lower, however, on terminal twigs than on the growth made 1 year earlier. On both upward- and on downward-growing terminal twigs, scales tended to orient the body with the anterior end directed toward the base of the twig. An attempt was made to provide an explanation for each of the relationships described.