90 INSECTS AFFECTING STORED PRODUCTS. 
area surrounding the germ. Whether this location of the exit hole, 
which shows the point at which the larva developed, is constant or 
not, or whether it is due to the manner of growing, or exposure to 
direct sunlight, or to shade, remains to be learned. It is not an 
economic proposition, but is a matter of some interest scientifically. 
Another lot of cowpeas infested by the four-spotted bean weevil 
was examined for comparison and gave similar results. Estimated 
by j>ercentages of exit holes, on the left side there were 48 per cent, 
on the right side 26 per cent, near the center 8 per cent, and at 
one end 6 per cent, while 12 per cent contained two exit holes. It is 
easy to separate the work of the two species in spite of this fact, 
however, because of the larger and somewhat more irregular exit 
holes made by the beetle of the four-spotted species. 
SUSCEPTIBILITY OF DIFFERENT VARIETIES OF COWPEA. 
From observation of the seed of cowpea grown uj)on the experi- 
mental plats of the department grounds and obtained from other 
sources it appears that certain varieties are preferred to others by 
the cowpea weevil as well as by weevils of related habits. "When the 
insect is extremely abundant it is not apt to discriminate between 
varieties; or. in other words, if the favorite plant is not present in 
the vicinity where the insect happens to abound, it will not hesi- 
tate to attack whatever variety may be ready at hand. There is the 
best of evidence for the belief that these weevils, like the grain 
weevils (Calandra), prefer the softest seed because more easily pene- 
trated, and that they experience more or less difficulty in entering 
harder seed. 
The favored variety here, and apparently elsewhere, judging 
mainly from seed taken direct from the field, appears to be the 
Blackeye, although all the varieties grown were attacked, the Lee 
variety less so than any of the others. The different varieties ob- 
served are listed in approximate order of infestation as foiloAvs: 
Blackeye. Browneye, Black, Lady, Rice, Manakin. Southdown, Red 
Ripper, Whippoorwill, New Era, Red Crowder, Unknown, and Lee. 
SUMMARY OF LIFE HISTORY. 
The cowpea weevil does not differ very strikingly in its life habits 
and economv from the common bean weevil. A careful study of 
the biology of each, however, has been rewarded by the development 
of certain points of difference, which may be briefly summarized. 
-The eggs are deposited on the outside of the growing pods in the 
field and upon the dried seeds, and are attached by a glutinous 
substance which covers the egg and extends somewhat around it. 
The larvae hatch from them in four, five, or more days, depending 
