

260 MISSOURI AGRICULTURAL REPORT. 



In pulling up the hills infested with the northern corn root-worm, 

 the roots will be found to be decayed, discolored, and especially the dis- 

 colored roots will be found to contain a dark, irregular line, extending 

 sometimes nearly the entire length of the root, which indicates the bur- 

 row of these insects. On cutting this open one will find this more or 

 less filled with droppingis, and the little larva can usually readily be 

 found inside of it. The larvae usually eat the roots some distance from 

 the stalk and mine up in an irregular direction toward, the stalk. After 

 killing the root the larva leaves it and seeks a fresh and healthy one, and 

 soon destroys it also, and in this manner each larva will kill many roots, 

 and as there are frequently fifteen or twenty larvae to a hill of corn, the 

 damage is sometimes great. 



The injury therefore that these insects do is by depriving the plant 

 of proper nourishment by destroying the roots entirely, or by weakening 

 them and thus preventing the plant from developing as fast as it should 



in the matter of growth, and 

 preventing the proper devel- 

 opment of the ear. In bee- 

 tle-infested hills one will 



frequently find six or eight, 

 Fig. 19. — Northern Corn Root-Worm, Larva, en- 

 larged six diameters. Or even twenty, of these 



larvae mining in the roots, and as soon as they have killed one root and 

 caused it to rot away, they move to another, so that a few of these in- 

 sects may practically keep the plant in check by mining in the roots as 

 fast as they develop. 



One can also determine the presence of these insects in the corn by 

 examining the worms or larvae themselves. They are white or light 

 yellow larvae, about two-fifths of an inch in length and about as large 

 around as a good-sized pin. The head is dark and there is a dark patch 

 on the last segment of the body. One of these larvae is illustrated, mag- 

 nified six diameters, in figure 19, and another one is shown in figin-e 20, 

 partly protruding from a root which has been broken oflf. 



The adult of the northern corn root-worm is a small beetle, shown 

 enlarged ten diameters in figure 18. They resemble very much some of 

 our squash beetles, and, in fact, are closely related to them. These ntjrth- 

 ern corn root beetles are of a beautiful green color when they have fully 

 matured, but when they first appear are of a decidedly yellowish color, 

 the green appearing a little later. 



These beetles feed upon the {X)llen of corn, especially where it col- 

 lects Ix^tween the leaves and the stalk, also upon the silk, and upon the 

 pollen and more or less upon the petals of the flowers of common weeds 



