Life History.

This Cephus pygmæus in its perfect form presents the appearance of a tiny wasp. Its body is nearly black. The legs of the male are chiefly yellow. Those of the female are ochreous with thighs black, except at their upper parts, and feet mainly brown. The wings are transparent, with dark articulations. About a dozen eggs are laid by each female, which deposits them singly in the steins of the plants, not far from the forming ear, whose situation is calculated with wonderful instinct. To effect this tiny slits are made in the outer cuticle of the stem by means of a wonderful apparatus consisting of a double set of saws, like carpenter's fine saws, as they have been described by Professor Westwood, with which the abdomen of the female is furnished. When the slit has been made the ovipositor is inserted, so that the egg is thrust deeply into the inner membrane of the stem. After ten days the larva appears. It is of a white, or creamy white shade of colour, shaped like a caterpillar (Nos. 4 and 5), having upon microscopical investigation six most rudimentary thoracic feet. In this respect this genus differs from other saw flies, whose larvæ are furnished with many feet. It has very strong jaws adapted for biting; with these it bores through the knots, devours the internal tissues of the stem, and gradually makes its way down to the bottom of the stalk; this it proceeds to cut through almost level with the ground, but a little distance above its chosen resting place on the crown of the root, where it spins a fine web, and soon puts on the pupa state, in which it remains until the spring ensuing. The perfect insect is seen first in the beginning of May.