64 
FIFTEENTH REPORT. 
A BACTERIAL DISEASE OF THE LARVAE OF THE JUNE 
BEETLE, LACHNOSTERNA SP. 
BY ZAE NORTHRUP. 
During the summer of 1912, the larvae of the June beetle, Liach nos- 
terna sp. committed serious depredations to crops. Specimens sent 
in to the Entomological Department by the farmers were found to be 
diseased and were turned over to the bacteriological laboratory for the 
determination of the etiology of the infection, and. if practicable, to use 
the living parasite as a remedial measure. 
This disease which is characterized bv a blackening of the affected 
parts was found to be a micrococcus, which was found microscopically in 
smears and in sections from diseased tissue. This organism was isolated 
from the affected tissues of a living grub and liquid cultures were used 
for the inoculation of soil in which healthy larvae were then placed. 
Oftentimes infection occurred within a short time; the most marked 
infection occurred when an incision was made in the integument, a 
characteristic lesion developing within twenty-four hours. 
It was discovered that an excessive amount of water in such inoculated 
soil favored the rapid progress of the disease. This seems to be one of 
the most important factors in determining the fatality of the infection. 
This disease may be transmitted characteristically to larvae of the 
Southern U. S. June beetle, AllorMna, nitida and to the American cock- 
roach, Periplaneta americana but is non-pathogenic to rabbits and 
guineapigs. 
The black pigment characterizing the disease is probably produced 
directly or indirectly bv the activity of the bacterial cells within the 
larvae tissue; the cocci and the integument cells in which they are im- 
bedded do not take the ordinary or the Gram stain but remain a dark 
brown in color. 
It has not yet been possible to try out this organism as a remedial 
measure for the destruction of the white grub. 
