THE CORN ROOT-WORM * 
(.Diabrotica longicornis, Say.) 
Order COLEOPTERA. Family Cheysomelid^. 
[A minute, slender, white grub, about two-fifths of an inch long, boring the roots of 
corn in the ground from June to August, transforming into a grass-green beetle which 
feeds upon the pollen and silk of the corn and upon the pollen ot other plants.] 
The earliest published mention of this insect as a species injurious 
to agriculture, is scarcely four years old, and yet it has become one 
of the most destructive insects of the corn crop in Illinois, second 
of late only to the chinch-bug in this respect, and scarcely second 
to that. Until recently it was known to entomologists as a common 
but harmless beetle, feeding in autumn on the flowers of the thistle, 
goldenrod and other plants of the family to which these belong 
(Composite); but none were acquainted with its life history, and 
none suspected it of any injury to agriculture. That it should have 
developed rapidly from this humble and insignificant condition into 
one of the worst pests to the staple crop of the State, is an alarm¬ 
ing phenomenon, and one which will well repay the most careful 
investigation. Now that its work is becoming known, there are many 
indications that its mischief as a corn-root worm was noticed occa¬ 
sionally, but not understood, as much as ten or twelve years ago; 
but it seems incredible that it can have appeared at any previous 
time in anything like its present numbers, or have done anything 
like the harm which it now inflicts on agriculture, without attract¬ 
ing the general attention of farmers or coming to the knowledge of 
such entomologists as Walsh, Riley and LeBaron. It is most prob¬ 
able, therefore, that this is another addition to the already long 
list of insects which are naturally harmless, but which have been 
stimulated to excessive multiplication and tempted to the most seri¬ 
ous ravages by the removal of some of the usual checks upon their 
increase. Just what the changes in the ordinary condition of its 
life have been, which have caused this destructive outbreak of the 
corn-root worm, we can not tell positively at present, although I 
shall have something to say on this point on another page; but, 
fortunately, we are able to determine wjjat must be done to reduce 
it to its former limits. The great importance of a full and wide- 
*For a summary of the contents of this article, see p. 30. 
