INSECTS INJURIOUS TO SWEET CORN IQI 



The Southern Corn Root-worm (Diabrotica 12-pnnclala Ol.). 

 ■ — The larvic of two species of leaf-beetles arc among the promi- 

 nent enemies to the culture of corn by destroying the roots. 

 One of these, the Southern corn root-worm is common nearly 

 throughout the United States, but as its name implies is most 

 destructive in the South. In the case of its attack not alone 

 roots, but underground stalks are injured. The other, known 

 as the Western corn root-worm, is somewhat confined to the 

 middle West, where it would be a very serious pest were it 

 not that farmers. generally in that region have adopted a sys- 

 tem of rotation which greatly reduces injury. The principal 

 form of its attack is in the interior of the fibrous roots, in which 

 minute, more or less longitudinal, burrows are formed. 



The larva of the Southern species is also called in the South 

 the "bud-worm" and "drill-worm." The beetle is commonly 

 known northward as the twelve-spotted cucumber beetle be- 

 cause of its frequenting the flowers of cucumber, as well as 

 squash, and other cucurbits in the interior of which one can 

 usually see one or more dusted with pollen, and the places where 

 they have gnawed the petals, for they are most omnivorous in- 

 sects and able to subsist on nearly any form of vegetation on 

 which they happen to alight. They are, in fact, to be found in 

 practically all fields of corn and in gardens everywhere. 



The beetle is yellowish green, and the wing-covers are 

 marked with twelve black spots (fig. 122, a). The length is 

 one-quarter of an inch or a little longer. The larva; (c) are 

 slender, thread-like, delicate and soft bodied, and white or yel- 

 lowish in color. 



The twelve-spotted cucumber beetle inhabits that portion of 

 America lying between the Atlantic seacoast to the base of the 

 Rocky Mountains, and from Canada to Mexico. It is a very 

 common species and most destructive in the South, where in- 

 jury is accomplished by its root-worm form as far northward 

 as Maryland and Virginia. 



