NOTES ON THE BIOLOGY OF THE CADELLE, 
TENEBROIDES MAURITANICUS LINNE 1 
By Richard T. Cotton 
Entomologist, Stored-Product Insect Investigations, Bureau of Entomology, 
United States Department of Agriculture 
INTRODUCTION 
The cadelle, Tenebroides mauritanicus Linne, is one of the commoner 
insect pests in stored grain and grain products. Although well known 
as a grain pest since the latter part of the eighteenth century, but little 
‘Careful study has been made of its life history and habits and much 
uncertainty exists regarding them. It is with the object of clearing up 
some of these uncertainties that the following brief notes are presented. 
OVERWINTERING AND EMERGENCE IN SPRING 
In the vicinity of the District of Columbia the cadelle overwinters in 
the adult and larval stages. Mature larvae that overwinter transform 
In the spring and large numbers of the newly emerged adults have been 
observed in May and June. These adults soon mate and shortly there¬ 
after oviposition begins. Freshly emerged adults collected May 25, 1922, 
began laying eggs July 1, 1922. This would seem to indicate a rather 
long preoviposition period, at least in the spring; however, female beetles 
that emerged later in the summer began laying eggs two weeks after 
emergence. Beetles that overwinter begin laying eggs with the first 
warm weather of spring. 
OVIPOSITION 
The beetles either lay their eggs loosely in the flour or other food 
material or tuck them into a crevice of some sort. They prefer to place 
them in some protected situation if possible, and advantage was taken 
of this habit to observe the number of eggs laid. Small pieces of sheet 
cork were fastened together with paper clips and placed on top of the 
food in the jar in which the female beetle was kept. The beetle invariably 
placed her eggs in batches between the sheets of cork, and it was a simple 
matter to change the cork each day and count the eggs laid. 
The eggs are placed side by side in batches containing usually from 
10 to 40 eggs. Table I gives a few records of oviposition. 
1 Accepted for publication Aug. 3 , 1923 . 
Journal of Agricultural Research, 
Washington, D. C. 
*agx 
(61) 
Vol. XXVI, No. 1 
Oct. 13, 1923 
Key No. K-xia 
