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EUROPEAN CORN BORER
(Pyrausta nubilalis (Hbn.))
Although the European corn borer attacks many cultivated crops
and weeds, it is discussed here mainly as an enemy of corn, its
favorite host plant. The eggs are laid overlapping one another like
fish scales, in small, flat masses of 15 to 20 or more on the undersides
of the corn leaves, and hatch in 4 to 9 days. The tiny borers, or
larvae, immediately crawl to protected places on the plants, where
they feed on the tissues of the immature leaves and tassels, and
eventually bore into and up and down inside the stalks and into the
ears. They become full-grown in about a month and, after provid-
ing an exit for the adult moth, change to pupae inside the burrows,
either at once or after an inactive period of varying length. In 10
to 14 days the adult moths emerge from the pupal cells and lay an
average of about 400 eggs 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. These insects pass the winter in the borer stage inside
infested stems of corn or other plants, and here they change to moths
late in the spring or early in the summer. There are one to several
generations a year, depending on the length of the growing season in
A. Destroy overwintering borers by disposal of infested cornstalks.
1. By feeding to livestock direct or as silage or in finely cut or
2. By plowing under cleanly 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.
3. 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 tend to
lay their eggs on the earliest-planted corn.
C. Plant resistant o- tolerant kinds of hybrid corn.
1. No immune strains are available, but hybrids differ in their
resistance and tolerance.
2. Select types that will mature when planted moderately late.
3. Consult your county agent or your State experiment station
on the best hybrids to plant in your locality.
D. Modify cropping practices.
1. Avoid sowing fall wheat or other small grain in standing corn
or corn stubble. The corn stalks should be plowed under
cleanly or cut at ground level and removed before seeding
2. Dispose of all early sweet corn stalks in fields and gardens -
immediately after harvesting the ears, by feeding, ensiling, or
plowing them under. Cobs and other remnants from the
cannery should be disposed of in the same manner. Ls3
E. Use insecticides where practical. 0g
1. Use of insecticides is at present practical only on early market -
or garden sweet corn.
2. Consult your county agent or State experiment station for >
current recommendations. rl
F. Apply as many of the operations suggested above as may be prac- ,-
ticable under local conditions. Community application of these z
methods is necessary for most effective control. J_--
June 1945 638266 U. S. Government Printing Office
For sale by the Superintendent of Documents, Washington 25, D. C. Price, 5 cents