INSECTS INJURIOUS TO CORN 



159 



wings expanding 1 J inches, the hind-wings being darker and bear- 

 ing faint markings (Fig. 135). The eggs are laid at dusk upon the 

 under surface of the leaves of the young corn, and hatch in from 

 seven to ten days. The eggs are flat, scale-like, and placed in rows 

 of from two to twenty-five, slightly overlapping each other. They 

 are 3-100 inch long, by two thirds as wide, at first a creamy-white, 

 but gradually becoming a reddish brown. The young larva bores 

 into the stalk, often destroying the "bud," and then at or near the 

 ground, where it burrows upward in the pith, seldom damaging 



FIG. 134. a, b, c, varieties of the larva of the larger corn stalk-borer; d, 

 third thoracic segment; e, eighth abdominal segment; /, abdominal 

 segment from side; g, same from above enlarged. (After Howard, 

 U. S. Dept, Agr.) 



the stalk above the third joint. As the borers grow they become 

 quite active and frequently leave and re-enter the stalk, thus mak- 

 ing several holes. The caterpillars become full grown in twenty to 

 thirty days, and are about one inch long, dirty-white, thickly cov- 

 ered with dark spots, each of which bears a short, dark bristle. The 

 mature caterpillar bores outward to the surface of the stalk, 

 making a hole for the escape of the adult moth, which it covers 

 with silk, and then transforms to a pupa in its burrow. This 

 occurs during July, and the moths of the second generation emerge 

 in seven to ten days. The second brood larvae feed on the old 

 stalks, tunneling them between the second joint and the ground, 

 and become full grown about harvest time when they go into winter 

 quarters in the root as above described. 



