LEAFLET NO. 34
CONTROL of
CORN ROOTWORM in CORN
W. G. EDEN, Associate Entomologist
F. S. ARANT, Entomologist
The southern corn rootworm, more
generally known 
as the "budworm",
frequently causes severe injury to
corn in Alabama. The life history
and cultural control of the insect
were determined and published in
Alabama Experiment Station Bulle-
tin No. 230 in 1929. That work was
drawn upon for the accounts of life
history, damage, and cultural con-
trol given in this report. Experi-
ments on control of the corn root-
worm with insecticides have been
conducted over a 3-year period at
the Tennessee Valley, Wiregrass,
and Gulf Coast substations, and at
the Plant Breeding Unit. The con-
trol practices with insecticides
recommended in this leaflet are
taken from the results of these ex-
periments.
LIFE HISTORY and DAMAGE
The adult of the southern corn
rootworm is commonly known as the
spotted cucumber beetle. In Ala-
bama it overwinters in rubbish, win-
ter legumes and other green plants.
Egg laying begins very early in the
spring. Adults have been observed
feeding and laying eggs on warm
days in mid-January. However, the
mass of first generation eggs is
laid in March. Eggs, which are de-
posited in the soil, hatch in 8 to
12 days and the larvae feed on un-
derground parts of green plants. The
larvae feed for about 2 weeks after
which they pupate (go into inactive
stage) for about 1 week. The time
required for development from egg
to adult varies considerably with
temperature; usually it is 4 to 5
weeks during warm weather.
Most injury to corn is caused by
the larvae which occur in the soil.
The larvae are greedy feeders and
may cause severe or even fatal in-
jury to young corn plants. They
feed on the roots or bore into the
base of the stems. The plants be-
come stunted and appear yellow in
color but may later become more
vigorous and produce grain. Boring
AGRICULTURAL EXP ERIMENT STATION
o j 4e ALABAMA POL.YTECH NIC INSTITUTE
1 m _T __ m _
JANUARY 1953
E. V. Smith, Director Auburn, Alabama
into the stem by the larvae causes
the buds to wither and die; the en-
tire plant is often killed outright.
Corn may be attacked from the time
the seed germinate until the plants
are several inches high.
Injury from the rootworm is most
generally found in early corn on
bottom lands and in corn following
winter legumes turned under. The
worst injury usually occurs during
cold, wet springs.
CULTURAL CONTROL
Injury from the corn rootworm to
corn following winter legumes turn-
ed under can be almost completely
avoided by properly timing the date
of turning the legumes and planting
the corn. In the latitude of Auburn,
Alabama, the best procedure is to
turn and disk the legumes on or be-
fore April 15 and plant the corn
early in May. The corn may be
planted 1 or 2 weeks before May 1,
provided the weather has been warm
and reasonably dry and the legumes
were turned before April 1.
There are no data available to
indicate the best time to turn le-
gumes and plant corn to avoid root-
worm injury in different sections
of the State. It is logical that the
date of turning and planting should
be a few days earlier in southern
Alabama and a few days later in
northern Alabama than in the vicin-
ity of Auburn. During extremely
cool springs, the date of turning
and planting in any locality should
be later than during a more nearly
normal spring.
CONTROL with INSECTICIDES
Experiments have been conducted
on two methods of using insecti-
cides to prevent injury from the
corn rootworm. They are mixing
the insecticides with the fertilizer
and seed treatment. Research is
still in progress, but to date it ap-
pears that more effective control
can be obtained by applying the in-
secticides in the fertilizer than by
seed treatment.
Mixing with the fertilizer. Effec-
tive control of the corn rootworm
has been obtained by mixing dilute
dust formulations of insecticides
with the fertilizer and applying the
mixture at planting time. Aldrin,
dieldrin, chlordane, parathion, to-
bacco dust, DDT, BHC, lindane,
and toxaphene were all tested at
various rates. Some control was
obtained from all of the insecticides
except tobacco dust. The most con-
sistently effective treatments were
aldrin and dieldrin at 1 pound of
technical material per acre. Where
rootworm infestations were severe,
the use of aldrin or dieldrin has re-
sulted in increased yields of as
much as 20 bushels of corn per acre
over no treatment. One pound of
lindane per acre was also effective,
but it tended to reduce the yield of
corn, especially on sandy soils.
Best results have been obtained
by mixing the proper amount of
dilute insecticidal dust with the
amount of fertilizer to be applied
per acre. For example, 20 pounds
of 5 per cent or 40 pounds of 2.5
per cent aldrin dust contains 1
pound of technical insecticide. If
400 pounds of fertilizer is to be
applied to the corn, either 20
pounds of 5 per cent or 40 pounds
of 2.5 per cent aldrin dust should
be mixed with the 400 pounds of
fertilizer. The mixture should be
applied to the soil with a fertilizer
distributor in the regular manner.
Seed treatment. Research on the
control of the rootworm by treating
the corn seed with insecticides has
not been completed. Indications
are that this method of control is
promising. In one experiment where
seed were treated with 2.5 ounces
of 40 per cent lindane 
per bushel,
the yield of corn was 10 bushels
per acre higher than no treatment.
However, in the same experiment
the use of 1 pound of aldrin in the
fertilizer resulted in an increase
of 18 bushels per acre.
SUMMARY
1. Corn stands in Nlabomna are
often severely damaged by the corn
rootworm, especially following the
turning of winter legumes or in bot-
tom lands.
2. The damage to corn following
the turning of winter legumes can
be avoided by properly timing dates
of turning legumes and planting
corn. At Auburn least damage oc-
curred when legumes were turned
before April 15 and corn was plant-
ed in early May.
3. Effective control under con-
ditions of severe infestations has
been obtained by mixing insecti-
cides with the fertilizer and apply-
ing at planting time. Best results
were obtained with 1 pound of tech-
nical aldrin or dieldrin per acre.
4. Lindane seed treatments are
promising, but to date they have
not been as effective as insecti-
cides in the fertilizer.
Rootworm damaging corn seedling.
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