SB 
818 No. 66. 
C578 Sito aie ; 
aS ited States Department of Agriculture, 
BUREAU OF ENTOMOLOGY, 
L. O. HOWARD, Entomologist. 
THE JOINT-WORM,. 
(Isosoma tritici Fitch. ) 
By F. M. WEBSTER, 
In Charge of Cereal and Forage Crop Insect Investigations. 
Since the first known serious outbreak of this insect, which occurred 
in the wheat fields about Charlottesville and Gordonsville, Va., during 
the years 1848 to 1854, it has been reported at irregular intervals and 
in widely separated localities. While it is known to occur sparingly 
over most of the wheat-growing sections of both the United States and 
Canada, and probably does more damage than has generally been 
placed to its credit, its reappearance in the wheat fields of Indiana, 
Michigan, Ohio, Pennsylvania, West Virginia, Virginia, Maryland, and 
Fig. 1.—Isosoma tritici Pitch: Adult of the joint-worm, much enlarged (from Howard). 
Kansas in 1904, and in still greater numbers in 1905, serves to bring 
it again to notice. In 1904 some fields of wheat in eastern Ohio were 
so badly damaged that they were not harvested, and the present year 
a serious outbreak in northeastern Indiana has so discouraged some 
farmers that they are questioning the advisability of putting in a crop 
of wheat at all. In southwest Virginia the pest has been even more 
injurious in 1905 than it was the previous year. 
DESCRIPTION OF THE PEST. 
The fully developed insect, somewhat resembling a small winged 
black ant, is clearly shown, enlarged, in figure 1, its natural size being 
indicated by a line at the right. The color is black, with joints of legs 
