L EAFL ET NO. 36
CONTROL of
VETCH BRUCHID in 
ALABAMA
GEORGE H. BLAKE, JR., Assistant Entomologist'
and
W. G. EDEN, Associate Entomologist
1
The vetch bruchid, or vetch wee-
vil, does severe damage to vetch
grown for seed in Alabama. The
insect has no effect on the amount
of foliage produced, but it may
seriously reduce the germination
of seed. Seed that appear sound at
harvest may be worthless or very
low in quality. Visible damage 
ap-
pears a few weeks after harvest,
when the bruchids emerge from the
seed, leaving only empty seed coats.
LIFE HISTORY
The vetch bruchid adult is a
small, almost black, chunky 
beetle
about 1/8-inch long, resembling the
pea weevil, but less than half as
large. The bruchids pass the win-
ter in the adult stage, and begin to
come out of hibernation during the
first warm days of spring. By the
time vetch is in bloom, all of the
adults are out of hibernation 
and
widely distributed in vetch fields.
When the first vetch pods are formed,
the females begin to lay eggs, which
are attached to the outside of the
pods. They continue to lay 
eggs
on new pods as they are formed.
The writers acknowledge the coopera-
tion and assistance of the personnel of
the Tennessee Valley Substation.
The newly hatched larvae penetrate
the pod and feed inside the seeds.
The insects remain inside the seed
until the seed are harvested, or un-
til the pods burst open, when they
emerge as adults. There is only
one generation of bruchids per year.
They do not infest seed in storage.
CONTROL
Results of experiments show that
fumigation of newly harvested vetch
seed will prevent emergence of adult
bruchids. However, these results
proved of no value 
in control of the
ruchid, since by the time seed
were harvested their viability al-
ready had been destroyed by the
larvae. Therefore, both fumigated
and non-fumigated seed failed to
germinate. From these results it
was concluded that control measures
must be taken in the field to prevent
egg laying.
Field experiments on control of
the vetch bruchid have been con-
ducted at the Tennessee Valley
Substation for 3 years. Five and 
10
per cent DDT, 5 and 10 per cent
chlordane, 10 per cent toxaphene,
2.5 per cent aldrin, 1 per cent rote-
none, and 1 per cent parathion were
tested during this period to deter-
mine the materials and number of
applications most effective for con-
AGRICULTURAL EXPERIMENT 
STATION
ola/e ALABAMA POLYTECHNIC INSTITUTE
t. V i th, ectorl Auge burn Alabamaan n
FEBRUARY 1953
Auburn, Alabama
E. V. Smith, Director
trol of the bruchid. These materials
were applied to vetch as dusts dur-
ing pod-forming time at rates of 25
to 35 pounds per acre per applica-
tion. The first application was
made when the vetch was beginning
to bloom freely. The seed were
harvested by combine and held for
bruchid 'emergence. The degree of
control was measured by the num-
ber of adults emerging from the
seed after harvest.
One application of the dusts had
no significant effect on the number
of bruchids emerging from the seed.
Two applications of all the insecti-
cides, except parathion, caused a
significant reduction in the number
high.
husts of 2.5 per cent aldrin and
10 per cent DDT were used in an
experiment to determine the number
of applications needed for most ef-
fective control of the bruchid. Two,
three, and four applications of these
two insecticides were applied to
vetch during the blooming period
with 7 to 10 days between applica-
tions. Two, three, and four appli-
cations of each material caused
significant reductions in emerging
bruchids when compared with no
insecticidal application. 'The de-
gree of control increased as the
number of applications' increased
(Figure 1).
Figure 1. Number of bruchids emerging from seed of untreated vetch and 
of
vetch treated with two, three, and four applications of DDT and aldrin.
of emerging bruchids. The 2.5 per
cent aldrin and 10 per cent DDT
were more effective than the other
treatments. Although two applica-
tions of insecticides caused signifi-
cant reduction of bruchid infesta-
tion, this infestation was still rather
Four applications of 2.5 per cent
aldrin or 10 per cent DDT applied
at the rate of 25 pounds per acre
and at weekly intervals, beginning
when the vetch is blooming freely,
are recommended for control of the
vetch bruchid.
N umber of
bruchids emerging
per pound of seed
400
300 .
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SUMMARY
1. Unless control measures are
employed, the vetch bruchid does
severe damage to vetch seed pro-
duced in Alabama.
2. Fumigation of newly harvested
seed prevented emergence of adult
bruchids, but it had no effect on the
germination of the seed.
3. One application of the insec-
ticides tested had no effect on the
number of bruchids emerging from
the seed.
4. Two applications of 5 or 10
per cent chlordane, or 2.5 per cent
aldrin significantly reduced bruchid
damage. The aldrin and 10 per cent
DDT were more effective than the
other treatments.
5. Two, three, or four applica-
tions of 2.5 per cent aldrin or 10
per cent DDT at 25 pounds per acre
caused significant reductions of
bruchid infestations.
6. As the number of applications
of insecticides increased from two
to four, the degree of control of
bruchids increased significantly.
7. Four applications of 2.5 per
cent aldrin or 10 per cent DDT ap-
plied at the rate of 25 pounds per
acre per application and at weekly
intervals, beginning when the vetch
is blooming freely, are recommended
for vetch bruchid control.