22 
BULLETIN 1428, U. S. DEPARTMENT OF AGRICULTURE 
THE LARVA 
The young larva, after effecting its escape through one end of the 
eggshell, is almost transparent in appearance and is so small that 
it is scarcely noticeable to the unaided eye. It is sensitive to light 
and at once attempts to burrow out of sight within whatever food 
substance is at hand. If no food is present it will conceal itself 
within or beneath any object that affords shelter. 
FOOD OF LARVA 
The larva (fig. 9, A, D; fig. 12) is voracious and, with a favorable 
environment, will grow rapidly. It will feed on an almost endless 
variety of foodstuffs but does not thrive 
equally well on them all. It will feed on 
all grains and their milled products, such 
as corn, wheat, oats, barley, rice, all kinds 
of flours, meals, stock feeds, biscuits, and 
bread. It feeds freely in many kinds of 
nut meats and seeds and various dried fruits 
and vegetables. Although developing more 
rapidly on the germ of the grain, the ca- 
delle feeds also on the harder portions, and 
frequently, in the case of wheat, so eats 
the kernel that nothing is left but a thin 
shell. In feeding upon corn on the cob 
(fig. 4, C), the larva eats out the softer 
germ, thus forming a chamber in which it 
is frequently entirely concealed and from 
which it eats a longitudinal channel to the 
outer end and escapes from the kernel by 
eating a characteristic slitlike opening well 
illustrated in Figure 4, C. 
Effect of diet upon growth of larva. — 
During the season of 1922 hundreds of 
cadelle larvae were reared in the laboratory 
in individual vials, and several different 
foods were experimented with. It was 
found that the type of food used had a 
marked influence over the rate of growth 
of the larva. The larvae were placed in 
individual vials and kept under identical 
conditions as regards temperature and 
moisture. Each was supplied with an abundance of food, the only 
difference being in the kind of food supplied. The foods used were 
corn, Avheat, rough rice, Graham flour, barley flour, and refined white 
flour. The larvae fed upon corn, wheat, and Graham flour grew with 
great rapidity and completed their growth in approximately the 
same length of time. These larvae all hatched during the first week 
in May and completed their growth in about 69 days. Those fed 
on barley flour did not grow quite so rapidly but a few of them 
completed their growth about two weeks after the corn, wheat, and 
Graham-flour-fed larvae. Those fed on rough rice grew still more 
slowly and did not transform until the following summer. The 
larvae fed upon the refined white flour developed very slowly, many 
Fig. 12. — The cadelle larva. 
Commonly found crawling 
among grain kernels. It 
may appear glistening 
white or dull and pow- 
dered according to the ma- 
terial in which it is 
crawling. When full 
grown it is about three- 
fourths of an inch long 
