84 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 14 



tion for cribbing. The Reid's Yellow Dent, on the other hand, was soft 

 and spongy, and practically worthless. 



In 1920 further experiments were conducted. Varieties were selected 

 because of their known resistance to drouth and supposed adaptability 

 to the type of soil found in the counties most heavily infested with 

 chinch-bugs. The varieties used were White Democrat, Black Hawk, 

 St. Charles County White, Arlington Prolific, Pride of Saline, U. S. 

 Selection 77, Freed W. Dent, Colby Bloody Butcher, Lancaster Sure- 

 crop, U. S. Selection 133, Minnesota No. 13, Northwestern Dent, and 

 Gehu. These varieties of com were secured through the Crops Depart- 

 ment of the United States Department of Agriculture, from entomolo- 

 gists in adjoining states, and from the Crops Department of the Univer- 

 sity of Illinois. 



During the summer flight of the chinch-bugs, all varieties in the field 

 were heavily infested. There was a more noticeable difference in the 

 effect on the several varieties in this season's test than in any of those 

 previously conducted. By September 6th, every hill of two varieties 

 had been killed, all the others showing more or less injury from the bugs. 

 The White Democrat, Black Hawk, and St. Charles County White 

 were ih a fair condition, considering the severity of the infestation. The 

 com was harvested October 2d and carefully weighed by Mr. S. C. 

 Chandler of this office. The results show a variation in yield from 

 nothing in the case of Gehu and Northwestern Dent, to 16.5 bushels 

 per acre in the case of the White Democrat. Two fields of about twenty 

 acres each in another locality where chinch -bugs were very abundant 

 were planted half to Reid's Yellow Dent and half to White Democrat. 

 The com in these fields was harvested late in October, the White Demo- 

 crat making from twenty to twenty -five bushels per acre, while the 

 Reid's Yellow Dent was so badly damaged that practically none of the 

 ears had m.atured. No yields were taken. 



Field obser\''ations in the counties heavily infested with chinch-bugs 

 have shown the White Democrat com markedly resistant when grown 

 on fertile soil. No fewer bugs have been found on this com than on 

 other varieties. The higher yield of this and several other varieties 

 seems to be entirely due to their power to resist chinch -bug attack. 

 All are corns of the flint type. The White Democrat, which is a strain 

 of Champion White Pearl, has a thick, leafy stalk, and a blunt, rather 

 short, ear. The kernel is broad, smooth, and hard, with a high protein 

 content. Black Hawk, the next highest yielding variety in the 1920 

 tests, is a similar red corn. 



More extensive tests including a number of other varieties will be 

 conducted during next season. It is not thought possible to develop 



