JOINTWOKM FLIES. 6 
Missouri. It has been known as a serious wheat pest since 1848 and 
it is strange that it has not extended its range into the great wheat- 
producing States of Texas, Oklahoma, Kansas, Nebraska, the Da- 
kotas, and farther west. At present no satisfactory explanation of 
this fact can be offered, although the species undoubtedly will invade 
that part of the country sooner or later. Harmolita tritici has been 
confused in literature with H. hordei, H. secalis, H. captiva, H. va- 
ginicola, H. elymicola, and doubtless with others. It was first de- 
scribed by Asa Fitch (3) 1 in 1859 as Eurytoma tritici and was sub- 
sequently described under several names by various authors. En- 
tomologists disagreed for years regarding this species before the 
phytophagous habits were definitely established. 
MANNER OF INJTJEY. 
A plant infested by the wheat jointworm may not show any ex- 
ternal signs of infestation whatever, or the stems may be distorted 
and have wartlike elevations on them (PL II, C). In any case the 
stem at the point infested is hard and woody and where there is no 
distortion the point of infestation may be readily detected by pinch- 
ing the stem between the thumb and forefinger. These infested 
places usually occur above the second or third joint from the root 
but may occur above any joint. In badly infested fields several 
joints may be affected and a large number of plants may fall (PI. I, 
B), thus greatly reducing the yield. It is not necessary, however, 
that the plants fall or lodge to reduce the yield greatly. The writer 
has taken heads from healthy and from infested stems, carefully 
measured them against one another, and has found that the grain 
of the infested plants from the same number of heads of exactly the 
same length as the uninfested w T ere very much lighter and of much 
smaller volume (PI. I, A). 
When plants lodge or fall to a considerable extent the yield is 
far more reduced than when the plants remain standing. In the 
first place, the plants that fall, in nearly every case, will escape the 
binder. Should the binder reach them they will be bound so near 
the butt of the bundle that most of them will fall out with subse- 
quent handling. Could they be bound securely the yield would 
scarcely be 50 per cent as large as that from heads of equal length 
taken from normal plants. The grains, moreover, are small and 
somewhat shriveled. The inferior grain seems to be due to improper 
nourishment during the growing period. The young larvae develop 
in the walls of the stem and disarrange the fibro-vascular bundles, 
thus greatly weakening the stem at this point. A storm, light rain, 
or heavy wind will cause the plant to bend over at the point of in- 
1 Numbers in parentheses refer to " Literature cited," p. 26. • 
