138 FARM FRIENDS AND FARM FOES 



emerge as beetles during the later part of summer or 

 early in autumn. 



These beetles then deposit eggs in the same fields in 

 which they were developed and the eggs remain unhatched 

 until the following spring. If corn is then planted, the 

 larvae feed again upon the roots and repeat the injury of 

 the season before, but if the field is planted to some other 

 crop upon which the larvae are unable to develop, the in- 

 sects will die and the damage will be prevented. Conse- 

 quently this Corn Rootworm has been a blessing in disguise, 

 for it has compelled those farmers who were depleting the 

 fertility of their land by a constant succession of corn 

 crops, to adopt a system of rotation. The discovery of 

 the life history of the Northern Corn Rootworm and the 

 pointing out of the fact that its injuries may be prevented 

 by the rotation of crops is one of the most notable ex- 

 amples of the benefits to be derived from scientific ento- 

 mology. The credit for it is due to Dr. S. A. Forbes, the 

 state entomologist of Illinois. 



The insect known in many of the Northern states as 

 the Twelve-spotted Cucumber Beetle, is also known in the 

 South as the Southern Corn Rootworm. Throughout its 

 range, it feeds as an adult upon succulent leaves, and 

 probably develops as a larva upon a considerable variety 

 of plant roots. In Kentucky and some other Southern 

 states it causes much damage to corn crops. Its Southern 

 life history is briefly this : The adult beetles hibernate at 

 the surface of the soil or just below, in fields of clover, al- 

 falfa, and other crops. They come forth early in spring, 

 and as soon as the young corn plants are well started, they 

 deposit their eggs about the roots. The eggs soon hatch 

 into larvae that become full grown early in summer, chang- 

 ing to pupae and soon again into adults which appear 



