LONGEVITY AND FECUNDITY OF BRUCHUS QUADRI- 
MACULATUS FAB. AS INFLUENCED BY 
DIFFERENT FOODS 1 
By A. O. Larson, Assistant Entomologist, and C. K. Fisher, Junior Entomologist , 
Stored Product Insect Investigations, Bureau of Entomology, 
United States Department of Agriculture 
INTRODUCTION 
It is remarkable how writers have 
refrained from making definite state¬ 
ments in regard to the feeding habits 
of adult weevils, Bruchus quadrimacu - 
latus. The general assumption is that 
no food is required, and that as soon as 
the energy stored up by the larva is 
exhausted the adult dies. This is 
borne out by the fact that weevils of 
both sexes are smaller at the end of life 
than at the time of emergence; and the 
female shrinks to about one-third her 
former size. In warm weather this 
energy is used up more rapidly than in 
cooler weather. The insect therefore 
lives longer in a low temperature than 
in a high one, but does not produce 
more eggs during the long period of 
life than during the shorter period at 
the higher temperature. 
The few known statements regarding 
the feeding habits of this weevil are not 
altogether in accord with one another. 
In speaking of Bruchus chinensis , which, 
he says, is typical of the other bruchids, 
Kunhikannan (I) 2 says: 11 The adults ap¬ 
pear to take no food during their life.” 
Wade (5), speaking of B. quadrimacu - 
latus , says: “ Weevils were bred in suc¬ 
cessive generations, * * * the 
adults taking neither food nor drink 
throughout their existence without 
apparent injury to them or effect upon 
their activities. Under these condi¬ 
tions adult females were kept alive for 
as many as 40 days.” He says further: 
“That the adults will drink was 
demonstrated on several occasions when 
water was given them, of which they 
partook greedily. So far as could be 
learned, access to water did not stimu¬ 
late their activities or prolong their life. 
That they feed can not be stated 
definitely; none were ever observed 
to do so, although it is quite possible 
that they may feed some on the green 
pods and foliage of the host plant.” 
Sanborn (If), discussing the same weevil, 
says: “The adults are not as ravenous 
as the young or larvae.” Paddock and 
Reinhard (3) say: “The active feeding 
period is confined to the larval stage.” 
In the same publication they say: 
“The cowpea weevil [the common 
name which they apply to B. quadri- 
maculatus] has not been observed to 
feed on any solid food in the adult 
stage * * *. In the field the 
adults feed almost exclusively upon 
nectar secreted by the nectaries lo¬ 
cated at the base of the green pods.” 
In confinement the length of life of 
the adult varies from a few days to a 
few weeks, depending on the tempera¬ 
ture. In a warehouse the weevil gets 
no food, but finds conditions favorable 
for reproduction during the short time 
it lives. This is not the case in the 
field. There is a long period every 
summer during which there is no 
suitable place for oviposition in the 
field, but the crops become infested 
later. This would indicate one of 
three things: First, that infestation is 
caused by weevils which have emerged 
during the summer shortly before the 
crop is sufficiently matured for oviposi¬ 
tion to take place; or, second, that the 
female weevil has the ability in the 
field to assimilate material which should 
normally go to form part of the quota 
of eggs, as is claimed to be the case 
with poultry, thus being sustained 
until she finds a suitable place to de¬ 
posit the remainder of the eggs; or, 
third, that she consumed some kind of 
nourishment which prolongs her life. 
Experiments and observations indicate 
1 Received for publication July 26, 1924. Issued January, 1925. 
2 Reference is made by number (italic) to ■ 1 Literature cited, p. 3Uo. 
Journal of Agricultural Research, 
Washington, D. C. 
( 297 ) 
Vol. XXIX, No. 6 
Sept. 15, 1924 
Key No. K-145 
