ENEMIES AND DISEASES OF CORN 265 



the field soon after the crop is planted and before the crows 

 begin their depredations. Alcohol dissolves strychnine 

 more readily than water and its use is therefore recom- 

 mended. In small fields, scarecrows, or a string stretched 

 over the field with pieces of paper attached at frequent 

 intervals, are rather effective. 



INSECT ENEMIES 



320. Causes. Insect injuries to corn are more com- 

 mon in the southern states than in the northern states. 

 The larger number of these injuries are due to the continu- 

 ous cultivation of corn on the same land for a number of 

 years. They also occur more frequently after plowing 

 up sod land of long standing. Hence an important feature 

 in the control of many of the insect enemies of corn is 

 the adoption of short systematic rotations accompanied 

 by clean culture of the intertilled crops in the rotation. 



321. Corn bud-worms (Diabrotica 12-punctata) . 

 These slender worms represent the larval stage of a small 

 beetle commonly known as the twelve-spotted lady bug. 

 These beetles are about one-third inch long, and yellowish 

 green with twelve black spots on the wing coverings. The 

 larvae are slender thread-like yellowish white worms with 

 a brownish head. They are about one-half inch long. The 

 winter is passed in the adult stage under rubbish or trash 

 or any material that will furnish adequate shelter. The 

 life history of the corn bud-worm is briefly summarized 

 by Sherman as follows: 



"The adults pass the winter, emerge very late in the 

 spring, feeding on flowers and foliage, mate, and lay eggs 

 at the base of corn or other plants in which the worms 

 feed; the worms on hatching from the eggs, burrow into 

 the root or stalk of the plant attacked, become grown in 



