Observations on the Life History and Biology of Agromyza Laterella Zetterstedt. (Diptera).*

Abstract

In the spring of 1916, while studying the interrelation of insects to certain swamp plants near Ithaca, New York, my attention was called to the occurrence of galls on the common wild blue flag, Iris versicolor . The plants then were from six to ten inches high, with three or four leaves out. The galls were always found on the outer leaf of the leaf-bundle, the affected leaf ceasing to grow. This formation of the gall and the subsequent cessation of growth of the leaf very often affects the second or next inner leaf in a peculiar manner; the tip remains caught in the gall for some time, the growing leaf is bent out and in its rapid growth produces a number of wavy or undulating folds. Fig. 1 shows a photograph of a small group of plants with several galls and the characteristic appearance of the second leaf.