38 BULLETIN 1428, U. S. DEPARTMENT OF AGRICULTURE 
germ of the kernel and damaging many more seeds than they can] 
consume. The habit of the larva of crawling into any substance in 
search of a protected place in which to hibernate or pupate results 
in the presence of the cadelle in many supplies upon which it does 
not feed. Since the larva and the adult may bore into wood for 
hibernation or transformation, the woodwork of granaries and the 
dunnage of grain ships may harbor thousands of cadelles, which can 
remain in hiding for months and be ready to swarm out to attack 
the next consignment of a food commodity that may be stored near 
them. 
The adult cadelle is both predacious and granivorous and appears 
to produce more eggs if given animal food. Many adults live to be 
over a year old ; one has been known to live almost 22 months. The 
length of the preovi position period depends upon the time of year 
the adult emerges. Observations show that it may be as short as 
15 days and as long as 210 days. 
The eggs are laid loosely in flour or other food materials, or are 
tucked into crevices of any sort which offer protection. They may 
be laid daily or every other day, or more often at irregular intervals 
with 10 to 14 days or longer frequently intervening. The longest 
egg-laying period known covered almost 14 months, the first egg hav- 
ing been laid in August of one year and the last in October of the 
following year. Oviposition periods extending over one year are' 
common, but such records are usually made by females that hibernate 
during the winter. Adults emerging early in the spring may com- 
plete their oviposition before winter. The largest number of eggs 
deposited by a single female was found to be 1,319; the minimum, 436. 
The incubation period was found to range from a minimum of 7 
days, when the mean temperature was 80° to 85° F.,to a maximum of 
15 to IT days, when the mean temperature for the period was 70° 
to 71° F. 
The larva is not considered to be predacious. Larvae grow best 
when fed upon corn, wheat, and graham flour, when they may com- 
plete their growth in about 69 days. Those fed on rice grow more 
slowly. Those fed upon refined white flour develop very slowly. 
When given the most suitable food and normal surroundings, a great 
many larvae complete their development and transform to pupa? 
within 3 months, a majority of them within 7 months, and all 
within 14 months. All larvae hatching in March and April at 
Washington completed their growth and transformed the same year ; 
90 per cent of those hatching in May transformed that year, 40 per 
cent of those hatching in June, 10 per cent of those hatching in July, 
and none of those hatching during August or later transformed the 
same year. Beared larvae having the shortest larval life and those 
having the longest larval life all hatched in June of the same year 
and were reared under identical conditions. Under less favorable 
conditions a larva has required as long as 1,248 days for development, 
but such long developmental periods are abnormal. 
When about to transform, the larvae form pupal chambers, usu- 
ally by burrowing into some substance like wood. Once the cham- 
ber is sufficiently large it is sealed with borings mixed with a 
larval secretion. After a prepupal stage averaging about 9 days, 
the pupal form is assumed. The pupal stage lasts from 8 to 25 
