Factors Affecting the Proportion of Alate and Apterous Forms of Aphids.

This paper embodies the results of work done by the writer while pursuing graduate work at the Kansas State Agricultural College. Experiments on factors affecting wing-production in aphids were carried on from September, 1919, to March, 1920. A second series of experiments were conducted in December, 1921, and January, 1922. Considerable work was done while away from college in rearing, preparing and drawing specimens. Credit is due Dr. M. C. Tanquary, under whom the writer began the work, for suggesting the investigations and furnishing starting points; and to Dr. Tanquary, Dr. R. C. Smith and Prof. G. A. Dean for many helpful suggestions. The object of the experiment was to study the factors causing appearance of the different forms of aphids; to test conclusions reached by other workers; to look for any previously unsuspected factors; and endeavor, if possible, to formulate a theory which would account for all results.