EUROPEAN CORN BORER

a. Egg mass on under side of leaf; b, larvae in stalk and ear of corn; c. pupa in stalk; d, female moth; e, male moth; f, borings from burrow of larva. (Egg mass, about three times natural size, other stages, about one and one-fourth times natural size.)

EUROPEAN CORN BORER

The European corn borer attacks many cultivated crops and weeds. Its favorite host plant is corn. The eggs (laid overlapping one another like fish scales in masses of 15 to 20 or more on the under sides of the corn leaves) hatch in 4 to 9 days. The tiny borers immediately crawl to protected places on the plants, where they feed on the tissues of the immature leaves and tassels. Eventually they bore into the stalks and ears. They mature in about a month and, after providing an exit for the adult moth, change to pupae inside the burrows, either at once or after an inactive period. In 10 to 14 days the adult moths emerge from the pupal cells and lay about 400 eggs each on corn or other plants that they may find in an attractive stage of growth. The moths live from 10 to 24 days. They are active fliers during the evening or night and may migrate several miles. The insects pass the winter in the borer stage inside infested stems of corn or other plants, where they change to moths late in the spring or early in the summer. There are one or more generations a year, depending on the length of the growing season in different latitudes.

Control: A. Destroy the overwintering borers by disposing of the infested cornstalks by feeding to livestock direct or as silage or in finely cut or shredded form; by plowing under clean in the fall or in early spring before the moths emerge, using attachments such as trash shields, wires, or chains to insure burial of all stalks; or by burning infested plants completely, where other methods of disposal cannot be used.

B. Plant as late as practicable, but only within the normal planting period adapted to the locality. Moths of the first brood lay their eggs on the earliest planted corn.

C. Plant resistant or tolerant kinds of hybrid corn. No immune strains are available, but hybrids differ in their resistance and tolerance. Select types that will mature when planted moderately late. Consult your count), agent or your State experiment station on the best hybrids to plant in your locality.

D. Modify cropping practices: Avoid sowing fall wheat or other small grain in standing corn or corn stubble. Plow the cornstalks under clean or cut them at ground level and remove them before seeding small grain. Dispose of all early sweet cornstalks in fields and gardens immediately after harvesting the ears, by feeding, ensiling, or plowing them under. Dispose of cobs and other remnants from the cannery in the same manner.

E. Use insecticides where profitable. Consult your county agent or State experiment station for current recommendations.