81 
190'±, we saw a full-grown larva leaving 
morning. It climbed cautiously down 
crawl out on a branch near the ground. 
a cotton plant at 9.30 in the 
the stem, once stopping to 
FORMATION OF THE PUPAL CELL. 
Once a larva has reached the ground, it proceeds at once to select a 
suitable place to burrow beneath the soil. Under ordinary conditions 
not much time is lost in choosing the proper site, which is usually not 
more than 1 or 2 feet from the base of the plant. When confined 
within a small space a few minutes are always sufficient. It now begins 
to push its head against the soil, at the same time swinging it slightly 
from side to side, and thus throws up a pile of loosened particles of 
earth. (See PL XII, fig. 1.) The diameter of the hole when excava- 
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r 
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1 
» 
' 
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Fig. 8. — Diagram of different types of pupal cells (original). 
tion begins is about twice that of the larva, but soon becomes blocked 
up by the loose earth. The time required to get beneath the surface 
varies anywhere between five minutes and three-quarters of an hour 
or even much longer, depending on the texture of the soil and the 
activity of the larva. When it has passed from view beneath the sur- 
face it continues to work down in a more or less slanting direction to 
a depth of from 1 to 7 inches, leaving the pile of loose earth to mark 
the point of its entrance. So far all its actions have been preliminary 
to forming the pupal cell, which is not constructed along the path by 
which the larva entered the soil, as had been generally supposed. 
