71 
ON A BACTERIAL DISEASE OF THE LARGER CORN- 
ROOT WORM (Diabrotica, 12-pvnctata, Oliv.). 
In July, 1889, information was received through Air. A. L. 
Hay, of Jacksonville, of an injury to corn in his vicinity which 
proved to be due to the larva of Diabrotica 12-punctata attack- 
ng the corn as a root worm, like the better known related spe- 
ties D. longicornis. The apparent effect upon the corn was 
practically the same as in the case of the corn-root worm just 
nentioned, the destruction of the roots dwarfing the plant and 
permitting it to fall readily by its own weight. The roots were, 
lowever, not as regularly burrowed as by the smaller larva, but 
vere more completely excavated, usually all the softer interior 
part being eaten away and the remainder dead. Frequently all 
die roots of a plant, large and small, were either eaten, or rotted 
iway because of the injury, leaving only the merest stubs at¬ 
tached to the stalks. Most of the stalks had also been eaten 
nto below or near the first circlet of ‘‘brace roots,*’ and some¬ 
times also behind the lowest leaf sheath. 
In a single patch of sweet corn nearly every hill was affected, 
md the damage was estimated at fifty per cent; and in field 
•orn adjacent as many as fifty larvae and pupae were taken from 
i single hill. Many other fields near Jacksonville were similarly 
attacked, the damage varying greatly from field to field, but 
lie general average for the neighborhood being estimated at 
ibout five per cent. 
The insect occurred at this time in all three stages of larva, 
pupa, and imago, the transformations of course being effected 
n the earth. Some pupae were as much as four inches beneath the 
surface, and a foot or two from the nearest hill of corn. Lar¬ 
vae of this generation were found thereafter in corn fields at 
Champaign, upon roots of corn, until August 8, and pupae un¬ 
til August 16. imagos being in the meantime extremely abundant 
n corn fields, feeding largely upon the silk and pollen of the 
orn at the tip of the ear. Young larvae, of a probable second 
•■eneration,* were observed by an assistant, Mr. Marten, at 
* Complete proof of the occurrence of a second generation in Kentucky has been pre¬ 
sented by Professor H. Garman, of the Agricultural Experiment Station, at Lexington, 
nan elaborate article on this insect, treated as a corn-root worm, published in “Psyche,’ 
rol. C (1891), pp. 28, 44. 
