4 BULLETIN 1137, U. S. DEPARTMENT OF AGRICULTURE. 
A little later in the spring an excessive number of tillers becomes 
strikingly evident, giving the diseased plants a rosette appearance 
(PI. II, B). Later, the underground portion of the older tillers 
develops a brown, rotted condition (PL I. C). 
SUMMER PERIOD. 
Field symptoms. — In ease of badly infested wheat fields, those 
plants which escape or resist rosette develop and form a thin 
stand of grain, and the diseased plants under usual conditions slowly 
recover by sending up straggling secondary tillers. In the case of 
the early death of diseased plants, the thick tufts of plant remains 
will be found on the ground usually until after harvest, except during 
seasons of heavy rainfall, when these plants are practically all 
washed away. 
Recovering diseased plants do not ripen until after the healthy 
plants: hence, as the healthy plants turn in color, at maturity the 
diseased areas show up conspicuously as green spots in the ripening, 
liealthy grain. 
Plant symptoms. — In the case of diseased plants which do not re- 
cover, their dead remains, consisting of low compact tufts of tillers 
and leaves, will be found in place on the ground except where thev 
nave been washed away. Plants which recover consist of a number 
of straggling secondary culms coming up from the stool of dead fall 
tillers and leaves. Such secondary culms may or may not produce 
Leads. In some cases remarkable recovery occurs, especially on rich 
moist soil, but usually very small imperfectly filled heads develop. 
Frequently, plants are found in which only part of the tillers are 
diseased. In such cases the healthy tillers usually develop normally, 
resulting in a plant consisting of a few normal tillers with dead 
fall tillers at the base and perhaps a few secondary tillers attempting 
to attain maturity. 
SYMPTOMS PRODUCED BY THE HESSIAN FLY. 
FALL PERIOD. 
Field symptoms. — A wheat field infested with the Hessian fly is of 
a shade of green darker than normal, with a certain bristling- appear- 
ance due to the stiff and upright leaves of the infested plants. As 
the season advances, the seemingly healthy appearance gives way 
to a more or less ragged, sickly stage, described by the farmer as 
u going back." 
Under certain conditions seemingly dependent upon the response 
of the wheat plant to soil variations, there may be a decided field 
spotting due to fly infestation. These spots or patches are usually 
associated with such conditions as soil color, type, topography, and 
exposure. 
Plant symptoms. — In the case of an infested plant, the central 
shoot is usually absent, and the leaves are broad, short, more or less 
stiff, and of a dark-green color (PL II, E). By stripping down the 
leaf sheath, the larva or the puparium (flaxseed) can easily be found 
near the base of the plant (PL III, E). The presence of a single 
small larva or a flaxseed is sufficient to have caused the characteristic 
appearance of the wheat plant. An infested plant may produce a 
few normal tillers or it may be killed, depending upon the degree of 
infestation. In the latter case, as the season advances the plant 
