14 
BULLETIN 94. 
WESTERN WHEAT-STEM MAGGOT, <Pegomyia cerealis n. sp.*) 
O11 the 5th of last May complaint came to this office that a 
wheat field that was looking all right ten days before had, for 
some reason, died down badly. Mr. Johnson went to examine the 
field and returned with a quantity of wheat stems with maggots 
in their centers. There were ten acres in the field and the inju¬ 
ries were so severe that it was decided that all would have to be 
plowed under, which was done, and the field planted to sugar beets. 
The field had been sown to wheat for three years in succession 
and had been fertilized heavily with barnyard manure the past fall 
and sowed to winter wheat which grew but little in the fall but 
which made a fine stand in the spring. 
The maggots burrow down the centers of the stems and feed 
where the latter are most tender, an inch or two beneath the sur¬ 
face of the ground. At the time of examination, May 5, many 
light colored dipterous pupae were found an inch or two beneath 
the surface close to the plants upon which they had been feeding. 
These pupae brought into the laboratory began giving flies June 6. 
The early appearance of pupae in the field makes it seem likely 
that the eggs may have been laid the previous fall. If this was 
not the case, the flies must have emerged very early in the spring. 
DESCRIPTION. 
The maggots are dirty yellowish white in color and measurebetween 
6 and 7 mm. in length by 1.5 to 1.75 mm. in diameter. At the small or 
anterior end the two jaws show distinctly and at the posterior end the 
two spiracles are black and above them is a shining black plate or chi- 
tinous piece which terminates in two short stout spines. The puparium 
is like the maggot in length and thickness, it is straw-yellow at first but 
darkens rapidly as the time for the emergence or the fly draws near. 
The black plate and spines of the maggot also show plainly and the ex¬ 
treme anterior end is blackened. 
The Adult Flies. Female: length about 5.5 mm. exclusive of oviposi¬ 
tor. Color of head and body rather uniform light gray, set with large 
and small black bristles that arise, each from a small black spot. Eyes 
dark reddish brown, naked, separated in front by a space nearly equal 
to the diameter of an eye; antennse black, the aristae also black and 
slightly plumose to the tips. Color of head like that of thorax except 
for a slight golden tint upon the face. There are five moderately stout 
bristles in a row parallel with the inner margin of the compound eye on 
either side and another row of about 20 of these bristles along the pos¬ 
terior border of each eye, the two at the upper angle of the eye being 
larger than the others. On the thorax there may be distinguished one 
median and, on either side, two lateral darker stripes which are 
quite distinct, and upon each of which a row of stout black bristles 
arises. Scuttelum with four setae, two very stout ones near the tip 
and one not so large near each posterior angle. Abdomen rather thick¬ 
ly set with stout black setae of moderate size, the largest ones arising 
from near the posterior margin of the segments. Femora cinereous like 
the body except at the knees where they change to light amber which is 
the color of all the tibias; the tarsi of all the legs are deep black. The 
wings are hyaline, tegulae and sub-tegulae small and nearly equal and 
amber in color, as are all the large veins. 
^Specimens submitted to C. W. Johnson were referred to Mr. Coquillett.who deter 
mined them, “Near Pegomyia ceptorum, but apparently distinct.” 
