IOWA ACADEMY OP SCIENCES. 
187 
sheath downward with a peculiar sawing motion alternating 
with a slight pause for the deposition of an egg. 
The eggs are one and one-half millimeters by one -third mil- 
limeter, cylindrical, gradually tapering from a point near the 
head back to an obtusely rounded tip; the anterior end is cut 
off obliquely from 03ie side and rounded from the other, coming 
to an obtuse point. They are deposited in a continuous row, 
from thirty to fifty, side by side, curving slightly around the 
stem with their heads toward the edge of the sheath, from which 
they are distant about one-third the circumference. The time 
occupied in actual deposition is from twenty to forty minutes, 
but the selection of a location and the catching of the sheath 
edge often occupies several hours. 
Although the eggs were deposited through a period of two 
weeks or more they apparently all hatched at about the same 
time; the time evidently depending considerably upon favorable 
conditions of temperature and moisture, for, up to July 2d, no 
larvae had been observed either in the cages or in the field. On 
this afternoon the air was very oppressive, and remained so 
until cleared by a heavy thunder storm during the following 
night. On the morning of the 3rd they were observed just 
emerging from the eggs in the cage, and examinations showed 
that they had hatched in the field also. The earliest depo- 
sition from which they were observed to issue on this date was 
made May 28th, and the latest on June 9th, while the majority 
were deposited June 4th and 5th. This gives from twenty- six 
to thirty- eight days, with an average of about one month, as 
the period of incubation. 
The freshly hatched larvse have shorter and blunter heads 
than the adults, and are much more active, but within a week 
or two the head has elongated, and it has adopted the sluggish 
habit of the adult. 
Upon hatching, the larvse immediately arrange themselves 
along the base and margins of the broad leaves parallel to the 
veins, where they remain stationary for weeks at a time, so 
closely resembling the rust spots and discolorations occasioned 
by their punctures that the chance of their detection is slight, 
or, they ascend to the head, where they conceal themselves so 
effectually among the glumes and sheaths upon which tney 
feed, that one might carefully examine a head and pronounce 
it free from them, only to find, on shaking it violently, that it 
contained a whole colony. Here they stay until the head ripens 
