LEAFLET No. 8
Control of Insect Pests in Stored Grains,
Peas, and Beans
HE CONTROL of insects in stored grains, cowpeas, beans,
and other similar products is a major problem in Alabama.
The greater part of the damage to grain is produced by the com-
mon corn or rice weevil and the Angoumois grain moth, although
more than 40 different species of insects are known to attack
grain and grain products. The most serious damage to beans
and peas is produced by three species of small insectscommonly
called bean or pea weevils.
CONTROL BY HEAT
Pests of stored grains, peas, and beans can be successfully
controlled by exposing them to a temperature of 120 to 130
degrees F. for 4 to 5 hours. The seed should be thoroughly
dry when treated and should not be overheated or germination
will be injured. The entire mass to be treated should be slowly
brought up to a temperature of 120 to 130 degrees F. and held
at this temperature for 4 to 5 hours. This treatment kills all
stages of the insect.
The use of this method of control is rather limited because
of the lack of heating facilities.- Very few bins or cribs in Ala-
bama can be heated to the proper temperature. Many cooking
ovens, however, may be used satisfactorily for treating small
quantities of seed, provided a thermometer is used to make cer-
tain the correct temperature is maintained.
CONTROL BY FUMIGATION
Fumigation is by far the most common method of controlling
insects in stored products in Alabama. No elaborate equipment
is needed. The materials to be fumigated are stored in a tight
bin or other container and treated with a suitable gas.
Rocms or Containers Suitable for Fumigation.-The success
of the fumigating operation 
depends largely upon the tightness
of the crib or the container in which the grain is stored. Cribs
made of tongue-and-groove material, with double walls and
floors, are satisfactory for fumigating. Some cribs not con-
structed so well may easily be made tight enough. For example,
AGRICULTURAL EXPERIMENT STATION
OF THE
ALABAMA POLYTECHNIC INSTITUTE
M. J. FUNCHESS, Director
AUBURN
JULY 1934
several layers of heavy paper may be spread on floors that are
not sufficiently tight and a tarpaulin may be spread over the
corn or other products in the absence of a good overhead ceiling.
It is much more difficult to make loosely constructed walls tight
enough for a fumigation. Since the condition of such walls varies
so greatly, the individual farmer must use his judgment in re-
building them or in using tar paper, tarpaulins, or other ma-
terials to prevent the escape of the gas through the walls. Small
quantities of seed may be fumigated in a good barrel, an empty
calcium arsenate drum, a dry-goods box well lined with several
thicknesses of heavy paper, or some other similar container.
Grain may be fumigated with fair results out of doors. In
this procedure the grain is piled on dry ground and covered well
with tarpaulins. The tarpaulins must completely cover the pile
of grain and extend out over the ground around the pile. Soil
should be shoveled on the edges of the tarpaulins to prevent the
escape of the gas.
Material to Use.-Of the many different fumigants used to
control pests in stored products, carbon disulphide ("high life")
is perhaps the most satisfactory. This material is a clear liquid
that volatilizes rapidly forming a heavy gas which penetrates
well into piles of stored seed. It is both effective and economi-
cal. Carbon disulphide has the disadvantage, however, of being
highly inflammable; its vapors, when mixed with air, are violent-
ly explosive.
The amount of carbon disulphide needed to kill insects varies
considerably, depending upon the tightness of the fumigation
chamber. In a practically air-tight bin 5 pounds of the material
to each 1,000 cubic feet of content is sufficient. The average
tongue-and-groove crib in Alabama, designed especially for
fumigation, requires 8 to 10 pounds for each 1,000 cubic feet.
In many cribs 15 to 20 pounds must be used for the same amount
of space, if fumigation is possible at all. For fumigating small
quantities of seed in tight containers the correct amount of
carbon disulphide is 1 teaspoonful to a 1-gallon container or 1
pint (2 cupfuls) to a 60-gallon container.
Fumigating Procedure.-In fumigating grains, peas, or beans
stored in a bin, crib, or other container, the following procedure
should be followed:
(1) Determine the number of cubic feet in the room or con-
tainer and calculate the amount of carbon disulphide needed.
The cubic content refers to the capacity of the entire room and
not to the part occupied by the materials to be treated. It may
be desirable in a partly filled room, however, to spread a good
tarpaulin over the materials to be treated and fumigate only the
portion occupied by these materials rather than the entire room.
(2) Make the room or container as nearly air-tight as pos-
sible. All windows to cribs should be closed and paper should
be packed in the cracks around them. All other openings or
cracks of any kind should be tightly closed.
(3) Remove enough corn or other needed livestock feed to
last several days or until the fumigation is over and the grain is
aired out.
(4) Pour the correct amount of carbon disulphide in thin
layers in large shallow pans placed on top of the material to be
fumigated or pour it on gunny sacks spread over the material.
It is essential that the carbon disulphide be spread in thin layers
over a considerable area so that it can vaporize rapidly. On
such products as unshucked corn the liquid may be satisfactorily
poured on the sacks or even directly on the corn, while on such
products as shelled peas it is better to use shallow pans. It is
necessary to place the fumigant on or above the material to be
treated because carbon disulphide forms a heavy gas that tends
to settle downward.
(5) Close the room or container tightly and do not disturb
it for 36 hours. It is well also to post signs warning passers-by
of the fumigation.
(6) Open the room or container after about 36 hours and
allow it to air out thoroughly.
Precautions.-Several precautions are necessary in fumi-
gating with carbon disulphide. Extreme caremust be exercised
to see that no lighted lanterns or other fires are carried in the
vicinity of the fumigation as the fumigant is highly inflammable.
Even a lighted cigarette, an electric spark, or a spark 
from the
hammering of metals may cause an explosion. With the exer-
cise of reasonable care, however, carbon disulphide may be used
with relatively little danger.
Fumigation may be performed successfully only when the
weather is warm. The temperature should be 70 degrees F. or
above. During colder weather the insects are not active and
the fumigant is only slowly volatile.
All seed should be mature and thoroughly dry when fumi-
gated with carbon disulphide. The germination and feeding
qualities of dry seed are not injured.
Time to Fumigate.-It is not possible to make any definite
rule as to the best time to fumigate. Certainly cowpeas 
should
be fumigated soon after harvesting. The soft grained varieties of
corn should also be fumigated soon after harvesting, unless 
trap
crops and other good farm practices have been used to protect
the corn against weevil injury. Hard grained varieties may not
need fumigating until spring; it is possible they may not need
it then if practically weevil-free corn was stored in a weevil-free
crib. The use of good judgment is necessary to determine the
best time under a given condition.
Costs.-The cost of carbon disulphide is quite variable. In
one-pound cans the retail price ranges from about 30 to 50 cents
a pound; when purchased in 500-pound drums the price is 4
to 6 cents a pound. Savings may be made by purchasing large
quantities and holding over any unused portion until it is needed.
It must be tightly sealed in the original container and stored in
a cool place.
OTHER METHODS OF CONTROL
Weevils in corn may be at least partially controlled by grow-
ing corn with long, close-fitting shucks and by using trap crops.
A trap crop to collect the weevils consists of a few rows of corn
planted in each field two or three weeks earlier than the main
crop of corn. To be effective, however, the trap crop must be
harvested as soon as mature and thoroughly fumigated to des-
troy the insects trapped. If the corn is not harvested early, the
trap crop becomes a breeding place to build up a large popu-
lation of weevils which remains to infest the main crop of corn.
The main crop should be harvested as soon as well mature and
stored in an insect-free crib or bin.
To rid an empty crib of insects all old corn 
and shucks should
be removed. The walls and floors should then be thoroughly
swept and the trash and live weevils thus collected should be
burned. It is sometimes desirable to fumigate an empty crib
with sulphur dioxide, as the fumigation is more effective than
the "clean up" without the fumigation.
To obtain the sulphur dioxide 5 to 6 pounds of sulphur should
be burned in a bucket or other metal container for each 1,000
cubic feet of content in the crib. Wood "shavings" or chips
should be placed in the bottom of the bucket and the 
sulphur,
mixed with additional "shavings", should be added. 
A small
quantity of wood alcohol or gasoline should then be poured on
the sulphur and lighted cautiously. To reduce the danger 
from
fire, the bucket of burning sulphur must rest evenly 
on a flat-
tened mound of soil several times the diameter 
of the bucket.
Asbestos or other non-inflammable material 
may be substituted
for the soil.
Insect pests of stored peas and beans cannot be successfully
controlled by any of the so-called farm 
practices. If insect-free
seed is planted the injury in 
the field is less than when infested
seed is planted, but protection against 
injury in storage is neces-
sary in either case. Peas and 
beans stored in air-slaked lime
are not attacked by weevils. For 
small quantities of peas the
correct amount of lime is one pound to each two pounds 
of cow-
peas. For large quantities of peas one 
pound of air-slaked lime
mixed with three or four pounds of peas 
is sufficient.
Peas and beans that have been freed of weevils by fumigation
may be stored in heavy closely woven 
sacks or other suitable
containers to prevent or reduce reinfestation.
DEPARTMENT OF ZOOLOGY-ENTOMOLOGY