June, ’20] 
AINSLEE: CORNPITH WEEVIL 
275 
others seem to be crowded out or starved by having no fresh pith to 
work in: Whenever two or more larvae do persist for a time the pith is 
completely riddled with burrows and changed to a mass of finely 
granular frass. 
In Tennessee most of the eggs are deposited late in July and early 
in August, and two months later, about October first, practically all 
the larvae are mature. It is surprising how simultaneously the larvae 
in any given field mature and leave the stalk. It has repeatedly 
happened that in a field where scarcely an exit hole could be found one 
day, only an occasional larva could be found a day or two later. In 
middle Tennessee this general exodus occurs very near October 1. 
In almost every infested field a few larvae can be found in the stalks a 
month or more beyond the usual emergence date but such larvae are 
generally smaller and immature. They are either larvae hatching from 
very late laid eggs and without sufficient time to feed to maturity or 
those starved by the premature or rapid drying of the pith as the plant 
ripened or was killed by frost. 
The burrow ends, usually, at or near a node, sometimes running an 
inch or two below it. The exit hole may be at a node or anywhere 
between but the most usual place for it is just above a node, within an 
inch or two of it. This would seem to be a rather unsatisfactory point 
for the ensheathing leaf base often so tightly enfolds the stem that the 
larva to escape must cut its way through both the stem wall and the 
leaf sheath. In rare instances the sheath of the leaf below also over¬ 
laps this one so there are three tough walls to be cut before the larva is 
free. Often, however, after cutting through the stem wall there is 
space enough behind the leaf sheath for it to escape in which case the 
exit hole is not visible until the leaf base has been removed. 
The emergence hole is not round but more often distinctly oblong, 
with its long axis parallel to the stem, about .75 mm. wide and 1.50 mm. 
long. The hole appears too small to permit the passage of the satiated 
larva but observation shows that if the head emerges the body can 
follow. The edges of the hole are often not clean cut. The exit hole, 
like the egg puncture, is characteristic of this species and once observed 
can hardly be mistaken. 
There is nothing especially noteworthy in the rest of the life cycle. 
The larvae simply wriggle free from the corn plant, fall to the ground 
and enter the soil at some crack or irregularity. In dense soil they go 
down but three or four inches, in a cultivated field or in mellow ground 
from eight to ten inches, often below the furrow slice. One was found 
in the center of a large clod lying on the surface. After reaching a 
sufficient depth the larva by rotation forms a smooth compact-walled, 
more or less spherical cell in which it lies awaiting the time of pupation 
the following summer. 
