7 
Pupa.—wWhen first formed, the pupa (fig. 4, ¢) is light honey- 
yellow in color, soon changing to a rich mahogany-brown. It is 
about seven-eighths of an inch in length and is able to contort itself 
violently when disturbed. It lies in the cavity usually with the head 
up. On emerging, the moth leaves the brownish shell of the pupa 
case, partially withdrawn from the hole. 
Adult.—The female moth (fig. 4, @) varies in color from almost 
white to smoky yellow. The fore wings, which spread to about 14 
inches, are darker than the hind wings, and bear faint markings. 
When at rest the wings are held close to the body, forming an acute 
triangle. The egg laying is done for the most part either at night or 
in the dusk of evening, the moths flying rapidly from plant to plant. 
The male moth (fig. 4, 6) is usually somewhat darker in color than 
the female and always smaller. 
FOOD PLANTS. 
Besides corn and sugar cane, this borer has been reported as feed- 
ing on sorghum, Johnson grass, guinea corn, and grama grass. The 
injury to the four last-mentioned plants is never severe, but in plan- 
ning methods of control they must be considered and an examination 
made to determine whether or not they are harboring the pest. 
NATURAL CHECKS. 
The larger corn stalk-borer has very few natural enemies. A 
minute Hymenopterous parasite (Z7’richogramma pretiosa Riley) has 
in a very few instances been found living in and destroying the eggs. 
In one case ten of these minute parasites were reared from two eggs. 
The larva of a brown, velvety beetle (Chauliognathus pennsylvanicus 
DeG.) sometimes enters the holes in the stalks of stubble after the 
corn is cut and devours the caterpillars found therein. This larva 
has been found to be of great value in reducing the numbers of the 
borers in fields of sugar cane. The termites or white ants (Zermes 
flavipes Koll.), locally known as “wood lice,” have been observed 
destroying the larve in the stubble in the winter, although apparently 
only when the presence of the larve interfered with the work of the 
ants. In a few cases bodies of the borers have been found in the 
stubble killed by a fungus, as yet undetermined, which envelops their 
bodies in a white mold. Fungi, however, are too dependent on 
- weather conditions to be of any practical value in controlling the pest. 
PREVENTIVE MEASURES. 
Rotation is one of the best general preventives of injury from in- 
sects affecting field crops. Experience has shown that where corn 
has followed itself upon the same field for two or more years there 
has been a much greater loss from the borer than where an annual 
change of crop has been practiced. This is especially noticeable 
. (Cir. 116] 
