Control of Corn Insects and Diseases
N UMEROUS 
insects 
and diseases 
attack 
corn in 
the field 
and
several insects cause serious damage to corn in storage. It
is the purpose of this leaflet to describe briefly the more important
insects and diseases of growing corn and to give control measures
for them. Control measures for the insect pests of stored corn and
other stored products are given in Leaflet No. 8 of this Station.
CORN INSECTS
Southern Corn Root Worm
The southern corn root worm bores into the young stalks of
early corn planted on bottom lands or after winter legumes on
upland soil. As a result of this injury, the buds wilt and (lie and
the stand of corn may be greatly reduced. The larvae of this in-
sect (Figure 1) is a slender yellowvish-white worm about I 1, inch
long when full grown. The
adult is a yellow ish-green
beetle with a black head and
6 black spots on each wing;
it is about 
1
,i inch long.
Injury from the south-
S ern corn root worm may
be avoided or greatly re-
f"I (iE 1.-Larva of the Southern Corn 
duced by late planting.
Root Worm (Enlarg ed about 5 times). The exact date of planting
necessarily varies with the
season and locality. I)uring a normal season in the vicinity of
Auburn winter legumes on upland soils should be turned and
disked on or before April 15 and the coin planted early in May.
The date of turning and planting should be a few days earlier
in South Alabama and a few days later in North Alabama than
at Auburn. Bottom lands should be turned at least four weeks be-
fore the time of planting and should be kept free of vegetation until
the corn is planted. The corn should be plauted the first of May in
South Alabama and the latter part of Max in North Alabama.
A more detailed discussion of southern corn root worm in-
jury in corn following legumes is given in Circular 65 of the
Alabama Experiment Station.
Lesser Corn Stalk Borer
The lesser corn stalk borer eats holes in the unfolding leaves
of corn or bores into the base of the stalk. The most serious
damage is produced in corn on poor, ul)land, sandy soils. Out-
AGRICULTURAL EXPERIMENT STATION
OF THE
ALABAMA POLYTECHNIC INSTITUTE
M. J. FUNCHESS, Director
AUBURN
LEAFLET No. 9 (e vised Imn JULY 1934
breaks have occurred
recently in three year
cycles, i. e., in 1924,
1927. 1930, and 1933.
In addition to corn,
this insect attacks sor-
ghum, Johnson grass,
FIGURE 2.-Larva of the Lesser Corn 
Stalk cowpeas, beans, pea-
Borer (Enlarged about 
V'2 times). nuts, 
and several other
criolps.
The larva of the lesser corn stalk borer (Figure 2) is a slen-
der greenish worm slightly less than 1 inch long when mature.
It can usually be distinguished from other similar insects by the
presence of the tube-shaped web the 
worm spins at the surface
of the soil. The adult is a yellowvish-brown moth with a wing
expanse of about 1 inch.
No entirely satisfactory method of control is known for this
insect. Since the immature stages pass the winter in the soil,
plowing and harrowing late in 
the fall are helpful. Not only
should the main part of a field be cultivated but also the 
borders
and terraces, as the insect may breed in the wild plants there.
Heavy fertilization is another practice which is of some value in
combating the lesser corn stalk borer. The fertilizer 
does not
destroy the insects but increases the vigor of the corn, thereby
making it more resistant to insect 
attacks.
Southern Corn Stalk Borer
The southern corn stalk borer is another worm 
that bores in-
to the stalks of growing corn, causing the buds to 
die or weaken-
ing the plants so that they are easily broken down by the wind.
This insect is sometimes called the larger corn 
stalk borer. It is
a fat dirty-white caterpillar (Figure 3) and 
when full grown is
marked with numerous brown or black spots, on 
each of which
there is a short bristle. The mature worm is about 1 inch long.
The adult is a smoky-yellow moth with a wing expanse 
of about
1!/. inches.
Late planting, as recommended for the southern corn root
worm, is effective in controlling the southern corn stalk borer.
Another effective con-
trol measure is the de-
struction of corn stub-
bles in the fall. This t , 
'
practice is especially j 
' *
helpful, as the insect
passes the winter in
the base of the old
corn stalks. Crop ro- FIGURE 
3.--Larva of the Southern (larger)
tation is of value if the Corn Stalk Borer (Enlarged about 3',,2 times).
corn is planted a considerable distance from any field which
grew corn the previous year.
Corn Ear Worm
The corn ear worm is also called the boll worm and the
tomato fruit worm. It feeds in the unfolding leaves of young
corn and in the tassels and ears of older corn. The most serious
damage is produced in South Alabama, where late corn may be
almost ruined during certain years. The larva of this insect
(Figure 4) is a green or brownish-colored worm with alternating
light and dark stripes running lengthwise the body. It is about
2 inches long when full grown. The adult is a grayish moth
with a wving expanse of about 11 inches.
No entirely satis-
factory method of con- - :
trol is known for this ' :
insect. Since the worms y
usually become more
numerous late in the
season and do more
damage then than ear-
lier, early planting is ___
helpful in avoiding in-
jury. In planting early
to reduce the damage FIGURE 4.-La 'a i the %'n E11 
Worm
from the corn ear (Side and top views, enlarged about 1 11 times).
worm, however, the
chances of damage from the southern corn root worm and the
southern corn stalk borer are greatly increased. In the sections
of South Alabama where the corn ear worm is very destructive,
the corn should be planted early and thickly in the drill; it
should then be thinned to a stand about the first of May. It is
possible that the root-worm and borer injury to the early corn
may be so great some years that the corn will have to be "planted
over" rather than thinned, but the chance is worth taking, since
corn planted over will have as good a chance of missing the corn
ear worm as will corn which is planted late to avoid root-worm
and borer injury.
Fall plowing, as recommended for the lesser corn stalk borer,
is of some value in controlling the corn ear worm. Cooperation
of neighbors in plowing adjacent corn fields is necessary, how-
ever.
Long close-fitting shuck coverings help prevent corn-ear-
worm damage to the ears of corn. In selecting seed corn, there-
fore, only ears with long close-fitting shucks should be used.
Careful selection of seed corn will produce a strain of corn with
shuck coverings that offer partial protection not only against
ear-worm damage but also against damage from corn weevils
and other insects.
The best direct control known is obtained by dusting the
corn with equal parts of lead arsenate and talc. Several appli-
cations should be made at intervals of two to four days. These
dustings are usually made at the time of silking to prevent
serious damage to the ears but may be made earlier to reduce
damage to the buds. Dusting is recommended for corn in small
garden areas rather than in large fields.
Fall Armyworm
The fall armyworm feeds on the foliage and ears of corn
and on the foliage of grasses. It is sometimes called the grass-
worm. Although this insect occasionally produces serious dam-
age throughout most of the State, it is more common on low
lands along rivers. The eggs are laid in clusters on the leaves
of grass or corn and the larvae (worms) which emerge from
the eggs feed first on the under surface of the leaves; later they
eat practically the entire plant. Frequently the worms appear
first in grassy areas where they feed until the grass is consumed.
They then "march in great armies" to 
fields of corn, sorghum,
or other crops, devouring almost everything in their path.
The larva of this insect (Figure 5) is a caterpillar about 1i
inches long when full grown. It varies in color from tan or
green to almost black. Three narrow yellow stripes extend along
the back from head to tail and a wider dark stripe occurs on
each side. The front of the head is marked with conspicuous
white lines forming an inverted Y. 
The adult is a grayish,
mottled moth with a wing expanse of 11 inches.
The fall armyworm is attacked by birds and parasitic insects
but other means of control are usually necessary. Young larvae
are readily destroyed by thoroughly dusting the infested grass
or corn with sodium fluosilicate, lead arsenate or calcium arse-
nate. Sodium fluosilicate is apparently the most effective of
these materials, but may be difficult to obtain. The older
worms are much harder to kill than the younger ones. Sine
the first outbreaks often occur
in grassy plots, it is sometimes -
possible to control the insects
by making several dustings
before they "march" to the
corn fields. If they are al-
ready migrating when discov-
ered they may be stopped by
plowing a deep furrow across
the path of the worms. A
large turn plow or "middle
buster" is suitable for making FIGURE 5.-Larvae of the Fall Army-
the furrow. The worms are worm (Side and top 
views, enlarged
about 11/4 times). Note the two eggs
unable to cross the furrow if 
of a parasitic insect on the back 
of
it is deep and freshly made. the worm below.
A log may be dragged along the furrow at frequent intervals
to kill the trapped worms. It is advisable to dust all infested
areas and provide ditches or furrows to protect uninfested areas.
Billbugs
Several species of billbugs attack corn and serious injury
is sometimes produced by the adults eating holes in the unfolding
leaves anti by the larvae (grubs) boring in the stalks. Although
these insects are primari-
ly pests of chufas, nut-
grasses, sedges, rushes,
A and wild grasses on damp
lands, they may migrate
from these plants to corn.
Corn on land which has
recently grown any of
the regular host plants
is also likely to be dam-
aged.
FIGURE (.-Adult of a Corn Billbug The billbugs 
(Figure
(Enlarged about 5 times). 
6) are dark colored wee-
vils having an elongate
body and a well developed snout or bill. They vary in size from
about f to :;' inch in length, depending upon the species. The
larvae are white or yellowish-colored grubs without legs.
Several farm practices are effective in controlling billbugs.
Clean cultivation to keep down nut-grasses. rushes, moisture-
loving grasses, and related plants on land to be planted in corn
is one of the most important control practices. It is also helpful
to plant corn as far away as possible from uncultivated lands
growing the wild host plants and to plant 
crops other than corn
on such lands recently brought under cultivation. Crop rotation
is another practice which is of some value. The cooperation of
several farmers with adjoining land, however, is necessary to
make effective the recommended practices for the control of
billbugs.
Grasshoppers and Cutworms
Grasshoppers are not usually serious pests of corn but oc-
casionally a serious and destructive outbreak occurs in localized
areas of the State. Cutworms are more generally destructive
throughout the State. These insects are too well known to re-
quire any description.
Grasshoppers and most species of cutworms may be con-
trolled with poison bran mash. One of the best formulae for
this mash is as follows:
6
Coarse wheat bran--------------------100 pounds
Sodium arsenite ----------------------- 4 pounds
Syrup -------------------------------- 2 gallons
Water--------------------------------8-12 gallons
In preparing the above mixture the sodium arsenite and syrup
are stirred into about eight gallons of water. The solution thus
prepared is then thoroughly mixed with the wheat bran. Mixing
may be effected by placing the dry bran on a smooth floor or
tight wagon bed, "turning" it with shovels as in mixing ferti-
lizers, and simultaneously adding the poison solution slowly to
the bran. Additional water is added if necessary to make the
mixture moist; it should not be wet or soggy, but should be a
crumbly mixture when properly prepared. The above formula
will make enough bait to broadcast over approximately 20 acres.
Poison bran mash should be applied broadcast late in the af-
ternoon in the manner of sowing oats. Care should be exercised
to see that no lumps of material are scattered over the field or
left exposed elsewhere, as it is poisonous to all animals. When
properly applied, however, this material is not injurious to birds
or game animals.
If the poison mash is to be used against grasshoppers only,
the cost may be reduced by modifying slightly the formula given
above. The syrup may be omitted and 50 pounds of wheat bran
mixed with an equal volume of sawdust may be used instead of
100 pounds of bran. The sawdust used must be measured by
volume and not by weight because of the great variation in water
content of the material. Fresh pine sawdust should not be used,
but is satisfactory after it ages a few years. Mash containing
equal parts of bran and sawdust is as effective against grass-
hoppers as a bait containing the same amount of undiluted wheat
bran. Slightly less water may be needed when sawdust is used
than for bran alone.
The insecticides used in bran mash (arsenicals,) are slow-act,
ing poisons, especially against grasshoppers. A period of three
to five days may elapse before the insects are killed in sufficient
numbers to be noticed. Hence, it is essential that the bait be ap-
plied first while the hoppers are small. Additional applications
may be necessary to prevent serious injury.
Although poison bran mash is sometimes needed to control
cutworms, usually these insects may be controlled in small gar-
dens by collecting the worms by hand. The best time to collect
cutworms is just after dark when most species come above the
surface of the soil to feed. A strong flashlight is suitable to use
in locating the worms which should be collected on several suc-
cessive nights.
Other Insects
Other insects which attack growing corn include the sugar
cane beetle and several species of wireworms and white grubs.
All of these insects breed in sodded areas or other land growing
considerable amounts of grass throughout the year. The wire-
worms and white grubs live in the soil two or more years before
transforming into beetles, whereas the sugar cane beetle com-
pletes its development in one year.
Damage to corn is produced by the larval stage of the wire-
worms and white grubs and by the adult stage of the sugar cane
beetle. When corn is planted in grassy areas infested with these
insects they feed on the germinating seed, the roots, and the
stalks of corn, often causing serious damage.
The sugar cane beetle is a dark brown or black beetle about
1/ inch long; it is quite similar in shape to a common "June bug".
Wireworms are slender light-yellow to dark-brown worms with
conspicuously jointed bodies of rather uniform width throughout.
Many forms have a glazed wire-like appearance, whereas a few
have rather soft bodies. White grubs are the common soil "grub
worms" which are too well known to require description.
Clean cultivation to keep down the wild plants in which these
insects breed is helpful in controlling them. When sod lands are
brought under cultivation, they should be planted in cotton or
some other unsusceptible crop and cleanly cultivated for one or
two years before corn is planted. Small areas may be practically
ridded of these insects by turning hogs on the land in the fall so
they may root up and eat the worms.
CORN DISEASES
Smut
Smut may appear on any part of the corn plant above ground,
as stem, leaf, tassel, or ear., Boil-like swellings ranging from
one to several inches in diameter appear on the plant, especially
on the ear and stalk. When these swellings first appear they are
lustrous white; later they become lead colored, and finally black
and sooty. This black sooty mass consists of millions of spores
(comparable to seed) which are blown over the field by wind.
These spores may remain alive on old plant parts in the field or
even in the soil from year to year. Where smutted stalks and
ears are fed to cattle, the spores multiply abundantly in the
manure and this is one of the chief means of spreading the dis-
ease.
Control.-Since corn smut is worse in fields where corn is
grown continuously, crop rotation and destruction of diseased
stalks seem to offer the best control measures. Do not plant
corn on fields fertilized with manure from cattle which have
been fed smutted corn, as the spores of smut over-winter in the
manure.
Ear and Root Rots
The damage caused by these diseases is extremely difficult
to estimate. Sometimes ear rot and root rot are caused by the
same fungus but more frequently they are caused by different
fungi, even though the fungus attacking either the ear or the
root may readily go to the other of these parts of the corn plant.
There are a number of fungi that may cause these diseases and
rarely is there a year when some of these diseases do not appear
in the field. These diseases are usually more abundant and se-
vere in wet seasons.
Control.-There are a number of practices which will aid
in the control of these diseases, such as variety selection, crop
rotation, and soil improvement.
The grower undoubtedly will profit by crop rotation and
seed selection, even though the diseases are only partially con-
trolled. Field selection of seed corn should be practiced by the
farmer. Down stalks, small stalks, badly fired stalks, broken
ear shanks, ears with exposed tips, ears extremely large in
diameter, discolored, moldy and smutted ears are characters
that are often associated with diseased plants and should be
avoided. In corn, many of the above undesirable characters are
inherited. Field selection of seed corn for desirable plants has
proved most successful in obtaining disease-resistant and high-
yielding plants. (See Alabama Extension Circular 143, 1934,
for method of making seed selection.)
In some sections of this Country, particularly in the mid-west,
seed treatment has proved valuable but this has not been the
case here in the South.
DEPARTMENTS OF ZOOLOGY-ENTOMOLOGY AND BOTANY AND
PLANT PATHOLOGY