
2 
ie) 
larve from the young kernels without any apparent gnawing of the 
surface, causing the grain to shrivel and the heads to blight and be 
imperfectly filled. On occasions of unusual outbreaks of this insect 
the crop is sometimes completely ruined, and occasionally the losses 
over whole States have averaged from two-thirds to three-fourths 
‘of the entire yield, or amounting to many millions of dollars. Dam- 
age to this extent is, however, unusual, and the wheat midge, while 
ranking as one of the chief insect enemies of the wheat crop, is com- 
monly much less dreaded than the Hessian fly or the chinch bug. 
The period of attack of this insect in early summer depends very 
much on the season, being retarded by cold and hastened by warmth. 
Ordinarily the fly appears about the wheat by the middle of June, and 
is present depositing its eggs for two or three weeks. In wet seasons 
it may even remain in evidence until the middle of August. Dryness 
is inimical to it, and unusual moisture is very favorable for its oper- 
ations. It is especially active on cloudy days and at night. Wheat 
grown in low, moist land is therefore more subject to injury, and if 
unusually dry weather prevails during the period when the fly is 
depositing its eggs, little injury is done to the wheat crop, and, corre- 
spondingly, a wet season at the same period is liable to result in greater 
loss on account of this insect. 
Where they oviposit.—The exceedingly minute, oval, nearly cylin- 
drical eggs, pale red in color, are deposited singly or in clusters to the 
number of ten in the crevices in the wheat heads, most often at the 
extremity of the head, and usually in the crevices and openings which 
lead to the developing kernel. In about a week the eggs hatch, and 
the larve find their way at once to the kernel or germ. 
Vitality of the larva.—The life of the larva is about three weeks. 
The full-grown larva is fairly robust, oval in shape, and has a length, 
when in a quiescent state, of about eight-hundredths of an inch. 
When in motion, it extends somewhat and tapers markedly toward the 
anterior extremity. It now abandons the wheat head and descends to 
the ground, either by skipping or jumping from the plant or crawling 
down the stem in a pellicle of water, being practically amphibious. 
Many of the larve are still in the wheat heads when it is harvested 
and are carried away from the field when the wheat is stacked. Their 
vitality under these circumstances, as reported by Fitch and others, is 
something extraordinary, as they are able to survive for months without 
moisture or food. Those that enter the ground in the fall form minute 
cocoons not larger than a mustard seed, and when covered with dirt, 
as they usually are, are almost impossible of discovery. It is believed 
that they remain unchanged in the ground until the following spring, 
or probably until shortly before the appearance of the adult insect 
again in the wheat fields in June. 
132 
