Apr. 2,1917 
Wheat-Sheath Miner 
23 
SEASONAL HISTORY 
There is some doubt as to the number of broods of the wheat-sheath 
miner in a year, though there seem to be three full broods, with the 
hibernation spent in the pupal stage. 
The adult flies appear about May 20 and lay eggs in wheat seedlings 
until about June 10. On June 16,1916, no flies were caught over a badly 
infested field of wheat, though the day was ideal for making a collection. 
The flies were apparently through ovipositing and had disappeared by 
that time. 
The flies of the second brood emerged in the insectary about July 16, 
and lived until August 5. As pupae were sent in from the field about that 
time, from which flies were emerging, it appears that the second brood is 
present in the fields from about July 15 to August 10. This brood lays 
eggs in the leaves of the wheat and also in seedling volunteer wheat and 
grasses. The life cycle of this brood was carried out in the insectary, and 
the third generation of flies began to emerge September 7. By Septem¬ 
ber 10 all the pupae in the cages had emerged and the flies were put out 
of doors with wheat plants, to keep them under more normal conditions. 
They did not survive a sudden cold snap which occurred at Bozeman on 
September 13. 
The next generation, which is believed to hibernate as pupae and pro¬ 
duce the first brood of flies the following spring, has never been reared in 
the insectary; and it is only by means of a few scattering facts that the 
occurrence of this generation is suspected. 
Many farmers who were questioned concerning this insect told the 
writer that they had often found “a small, brown, wrinkled egg down 
next to the killed stalk in the winter wheat during the fall and winter.” 
By this they doubtless meant that they had noticed the pupa in the dead 
stalk. Some of these men had noticed the same thing in the stubble after 
cutting in August. Since winter wheat is planted after the middle of 
August and the second brood of flies is apparently through ovipositing 
before the wheat has come up, the pupae in the winter wheat must have 
been the result of eggs laid by the third brood of flies. During March, 
samples of winter wheat were sent in which contained pupae apparently 
identical with those of C. femoralis. These pupae never emerged, and the 
identity of the flies could not be definitely determined, though there is 
little doubt of their being C. femoralis. During the last week in Sep¬ 
tember, 1916, a visit was made to the badly infested locality. Pupae 
and fully grown larvae were found in timothy, volunteer oats, and wheat. 
These were apparently the third brood and indicate the pupal hiberna¬ 
tion, thus assuring three broods for the year. 
It does not seem likely that the pupae of the second brood would last 
through the fall and winter, since all those in the insectary had emerged 
by September 10. Neither does it seem likely that the adults would over- 
