ENTOMOLOGY 179 



Immediately upon leaving the egg in spring, the young larva 

 of the first generation, spinning a silken thread behind it, wanders 

 down into the throat of the plant as far as the water or dew usually 

 standing there will allow it to go, and begins to feed on the leaves, 

 going back and forth through yet unfolded clusters and soon rid- 

 dling the more tender leaves with aimless burrows. If the burrow 

 reaches the tender terminal bud where the future joints are being 

 formed, further growth at that point ceases and the plant becomes 

 stunted and misshapen, with no tassel. As the plant continues to 

 mature, the larva grows out, as the farmers say. It is more likely 

 that it is the evidences of its work and not the larva itself that grow 

 out; but for whatever reason, the caterpillar soon leaves the more 

 leafy portion of the plant and attacks the stalk at or near the ground. 

 Here a hole is cut through the outer wall of the stalk and the larva 

 burrows upward for a short distance, after which it seems to run 

 aimlessly through the pith, frequently even leaving the stalk en- 

 tirely and re-entering it at another point. Turning upward, the 

 caterpillar, when fully grown, bores toward the outside and cuts a 

 circular hole in the outer wall of the stalk. Then, after spinning a 

 few loose threads across this opening to keep out undesirable vis- 

 itors, it retreats a short distance, plugs the burrow below with di- 

 gested pith, and in the chamber tnus created slowly changes to the 

 next or pupal stage. 



The female moth varies in color from almost white to smoky 

 yellow. The fore wings, which spread to about 1V4 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 

 mule moth is usually somewhat darker in color than the female and 

 always smaller. 



Rotation is one of the best general preventives of injury from 

 insects 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 orop has been practiced. This is especially noticeable 

 where stalks or stubble from the previous year have been allowed to 

 remain undisturbed throughout the winter. The moths, upon emer- 

 gence in the spring, finding themselves surrounded by the young 

 corn, commence egg laying at once and escape the dangers encoun- 

 tered in searching for another field of corn. 



Another remedy, probably the best for this insect, is the thor- 

 ough destruction, some time before the period of emergence of the 

 moths in the spring, of all the stalks and stubble remaining in the 

 field from the preceding crop. If all this trash can be disposed of 

 before the opening of spring, the numbers of the pest must be greatly 

 diminished if not almost exterminated, for the only form in which 

 the insect passes the winter is that of the caterpillar, and the only 

 known location is in the lower tip of the corn root, snugly hidden. 

 Some few may, however, be found to survive in the root,- of the 



