157 
in which event, corn not succeeding’ corn may possibly suffer 
the following year.* The general damage to a field is in the 
worst cases sufficient to destroy the crop so far that the dis¬ 
gusted farmer turns his pigs into his corn to get what they can, 
and makes no attempt to harvest his crop. A badly infested 
field was described to me by Dr. Boardman in 1882, which is 
worthy of mention as illustrating one of the common effects of 
root injury by this beetle. “I should say,” he writes, “that one 
fourth of the corn in this field was rotlingor beginning to rot. 
I found, on cutting an ear open, that I could slice the cob as 
easily as if it were a turnip. The infested corn [in Stark county] 
is yielding from ten to fifteen bushels per acre.” 
Although the corn root worm beetle is distributed throughout 
the Mississippi Valley, and south even to Central America, it 
clearlv becomes comparatively rare southward, and has never 
been taken by us in Southern Illinois in any numbers, nor found 
injurious in the larval stage except in the northern two thirds 
of the State.! 
This root worm has not heretofore been certainly found in¬ 
festing anv other plant than corn,! and the amount of skilled 
attention which has been given to this point by entomologists 
and other accurate observers, makes it practically sure that it 
is so closely limited to corn at the present time in Illinois that 
we mav base our economic methods upon the supposition that 
it infests no other plant. 
FOOD OF THE BEETLE. 
The beetles, beginning to appear in June and continuing until 
November, feed entirely during this whole period upon the softer 
and more delicate parts of the vegetation present at the time. 
They collect the pollen from the tassels of the corn, or gather 
that which has sifted down among the leaves and collected at 
•their bases, where these join the stalk. They also gnaw away 
the fresh silk from the tip of the ear (where they may often be 
found congregated in numbers of a dozen to twenty, or more), 
probably thus doing a considerable amount of mischief by de¬ 
stroying the silk before it has serve 1 for the fertilization of the 
* As an example of this tendency to spread from the infested field. I may note the not 
uncommon occurrence at Rankin. Ill., July 1,1887. of t is corn root worm In a field of corn 
following oats, but only on that part of it which bordered an infested field in corn the pre¬ 
vious year. It, is possible that other instances of this kin i reported previous to 1891 may 
have related to the southern corn root wor n, Diabrotica 12-punctata. 
+ I now believe that the statement made by me in 188(5 (see “Entomologica Americana," 
Vol II p 174) to the effect that I found it injurious to corn in a field near Cairo, in Southern 
Illinois, which had been under water for n-arly three weeks in the spring, really referred 
to the southern corn root worm (l)iabrolica 12-puncta:a), of whose habit as a corn root 
insect nothing was at that time known. 
I A statement from a correspondent, published in my Twelfth Report (p. 19) that it i.s 
sometimes very abundant in the roots of pursl ne (Portulaeai, I believe to have been based . 
on the frequent occurrence in the main root of that plaqt, of the burrows of a coleopterous 
larva resembling the corn root worm, but certainly different; although never having bred 
it, I am unahle to identify it precisely. It is shorter than Diabrotica, and has the mouth 
parts black instead of brown. 
