CHAPTER IX. 





INSECTS INJURIOUS TO CORN 

 The Western Corn Root-worm * 



THROUGHOUT the corn States of the northern Mississippi Val- 

 ley, wherever corn is grown upon the same land it is subject to 

 serious injury by the Western Corn Root- worm, so called because 

 it first became injurious 

 in Missouri and Kan- 

 sas and gradually spread 

 eastward to Ohio, 

 though not injurious 

 south of the Ohio River. 

 Though the life history of 

 the insect has not been 

 entirely determined, the 

 following summarizes it 



as observed by Professors 



<3 A F^rHe" arH F 1VT FIG. 12 4. The western corn root-worm: a, 

 b. A. *ort>< b and *. M. beet]e; 6> larya; ^ enlarged leg of same; d | 



Webster in Illinois and pupa all enlarged. (After Chittenden, U. S. 

 Indiana. The eggs are Depk A 8 r -) 



laid in the early fall, within a few inches of the base of the stalk, 

 and just beneath the surface of the soil. The egg is a dirty white 

 color, oval in shape, and about one-fiftieth inch long. The winter 

 is passed in the egg stage, differing from most nearly related beetles 

 in this, and the eggs hatch in the spring or early summer. At first 

 the larvae eat the small roots entire, but later burrow under the 

 outer layers of the larger roots, causing the stalks on rich loam to 

 be easily blown over, or dwarfing the plant on poorer land so that 

 it produces but small ears. The full-grown larva is nearly white 

 with a brown head, a little less than one-half inch long by about 

 one-tenth inch in diameter. Three pairs of short legs are found 



* Diabrotica longicornis Say. Family Chrysomelidoe. (See F. M. Webster, 

 U. S. Dept. Agr. Bulletin No. 8.) 



143 



