THE DESERT CORK FLEA-BEETLE. 
11 
"feeding mines/' while in others the feeding may produce a groove 
along one side of the root, the larva finally entering the root and the 
tunnel being continued within the same. Often where two tunnels 
pass, the root is entirely cut off, and as is the case with small fibrous 
roots, they are often entirely consumed. This feeding habit fre- 
quently makes it quite difficult to locate any larvse except those that 
were completely matured, and hence they were usually found in the 
soil at some distance from the root. The larvse consume a consid- 
erable amount of food. A single larva confined in a plaster of Paris 
cage entirely consumed a section of root one-fourth of an inch long 
and one-sixteenth of an inch in diameter. 
LARVAL FOOD PLANTS. 
The food plants of the larvse do not differ materially from those 
of the adults. The amount of damage done to these various food 
plants does, however, differ con- 
siderably as between the larva and 
adult. Alfalfa is rarely, if ever, 
injured by the adults, while the 
larvae do a considerable amount of 
damage to alfalfa roots, especially in 
alfalfa fields which have been seeded 
to a grain crop such as barley, oats, 
or wheat during the winter. It is 
upon corn, however, that the larvae 
do their greatest damage. This is, 
of course, due to the fact that the 
feeding of the adults is concentrat- 
ed upon newly growing corn each 
spring, and egg deposition conse- 
quently becomes much heavier, the resulting damage being accord- 
ingly great. 
THE FREPUPA AND PUPA. 
When the larva becomes full grown it constructs an oblong earthen 
cell in which to change, (1) to a transitional or prepupal stage, and 
(2) after a further period of a few days, to the true pupal stage. 
These pupal cells average about three-thirty-seconds of an inch in 
length, the inner walls being quite smooth. In constructing its cells 
the larva, owing to the fact that it is longer than its cell, must be 
doubled back upon itself, thus working in very close quarters. As 
soon as the cell is completed the larva changes to a prepupa. In this 
stage the body length shrinks while the diameter greatly increases, 
and the larva changes to a plump, rotund object shaped like a ques- 
tion "mark. This stage, as shown by Table IV, varies in length 
from 2 to 8 days, the average being 3.4 days for 10 specimens. This 
Fig. 6. — Section of corn root showing injury 
by larvae of the desert corn flea-beetle. 
About one-half natural size. (Original.) 
