This insect reached the United States from Europe about seventy-five years ago and is now quite generally distributed through the eastern states. The elm is its only food plant, and the European elm generally suffers more from its attacks than the American species.

The insect passes the winter as the adult beetle, hiding in any protected places available, such as attics, old chimneys, etc., and is often found on the windows in houses in the spring, seeking to escape to the trees. The beetle is about a quarter of an inch long and about half as wide, and is yellow in the summer with a dark band on each side, but after wintering over, the yellow changes to a dull olive green.

After the elm leaves appear the beetles fly to the trees, and feed, eating irregular holes and laying their eggs. These are yellow in color and are placed on the under sides of the leaves, generally along a vein and in two rows, and number from a dozen to thirty. The beetle feeds and lays its eggs in this way for several weeks. The grubs which hatch from these eggs feed on the under surface of the leaves, leaving the upper surface entire, for fifteen or twenty days, then crawl down the tree to the larger limbs, trunk, or even to the ground, and pupate, either in crevices of the bark or on the ground, the adult beetles escaping from the pupae after about a week.

In the more northern states these beetles are the ones which winter over, and though they may feed somewhat on the leaves during the fall, do little injury. In the middle and more southern states, however, they return to the trees and lay eggs for a second generation of grubs, which feed during the late summer months and become adult before winter.

It is rarely profitable to spray twice for these insects - once as soon as the leaves have developed, and again about the time the young hatch - and the usual treatment is to spray with arsenate of lead, using about five pounds of the arsenate to fifty gallons of water, about the time the eggs hatch, the exact date varying considerably with difference of latitude. The spray should be directed so as to reach the underside of the leaves as far as possible, as the grubs feed only on that side.

If for any reason spraying is not possible or has been neglected, the trunk and larger limbs of the trees should be made quite smooth, to leave as few crevices as possible high up where the grubs might pupate, thus inducing them to come farther down where they may be destroyed by the use of a contact poison, such as strong kerosene emulsion. Sticky bands on a tree are of no protection against this insect, as the beetle flies freely.