| Insect |
Description |
Nature
& symptoms of damage |
Management |
---------------------------- Insect pests of seed and roots
---------------------------- |
| Wireworms
(true and false), families Elateridae and Tenebrionidae |
Larva of click
(true) or darkling (false) beetle; shiny, slender, cylindrical, and hard-bodied, range
from white or yellow, to brown. |
Feed on planted
seed and less on seedling plant roots. Damaged seed do not germinate, resulting in stand
loss. |
Encourage rapid
seed germination and rotate with non-host crop. Insecticide as seed, planter box, or
in-furrow treatment. |
| Red
imported fire ant, Solenopsis invicta Buren |
Social insect
lives in colony with several castes of winged reproductives and workers reddish brown to
black and 3-8 mm long; constructs mound. |
Chews through
thin seed coat and consumes embryo of planted seed; damaged seed does not germinate,
resulting in stand loss. |
Encourage rapid
seed germination by planting good seed into well-prepared seed bed and firmly packing
covering soil. Insecticide as seed, planter box, or in-furrow treatment. |
| White
grubs, Phyllophaga spp. |
Larva of May or
June beetle; "C"-shaped, white body, head and legs brown; last abdominal segment
transparent and digested material can be seen. |
Damage results
from larva feeding on roots; small seedlings often are killed, resulting in stand loss;
severely pruned roots result in stunting, plant lodging, and increased susceptibility to
drought and stalk rot organisms. |
Rotate with
nonhost crop. Base insecticide treatment on 1-2 grub/ft2 of soil; in-furrow
insecticide provides some suppression. |
---------------------------- Insect pests of seedlings
---------------------------- |
| Cutworms
(several species), family Noctuidae |
Smooth-skinned,
dirty gray or brown larvae 30-50 mm long. When disturbed, curl up tightly into a
"C" shape. |
Feed at night
and hide during day. Usually feed on seedlings and sever stems. Some feed on foliage, and
some feed entirely underground on seedling roots. |
Rotate with
nonhost crop, and clean cultivate before planting. Insecticide applied to soil or foliage
in late afternoon to prevent excessive plant or foliage loss. |
| Southern
corn rootworm, Diabrotica undecimpunctata howardi Barber |
Larva is 12 mm
long, creamy white and wrinkled, with a brown head. Adult is the spotted cucumber beetle. |
Larva chews
along roots or burrows into roots and crown, causing stand loss, stunting, deadheart, or
late-season lodging. |
Clean cultivate
2-3 weeks before planting. Base in-furrow insecticide application on history of problem. |
| Yellow
sugarcane aphid, Sipha flava (Forbes) |
Lemon-yellow
aphid covered with small spines and has two double rows of dark spots down the back; very
short cornicles. |
Attacks soon
after plant emergence. Injects toxin that causes purple-colored leaves and stunting of
seedlings; yellowing of more mature leaves and delayed maturity. |
Encourage rapid
plant growth until 5-leaf stage. Base insecticide treatment on percent infested plants --
10, 20, and 40 percent infested at 1-, 2-, and 3-leaf stages. |
| Chinch
bug, Blissus leucopterus leucopterus (Say) |
Adult is 5 mm
long, black with reddish-yellow legs and white wings marked with black triangular spot at
middle of outer margin; immatures resemble adults in shape but are wingless and reddish
with a horizontal white band across the back. |
Immatures and
adults congregate and feed behind sheaths of lower leaves; suck plant juice and cause leaf
reddening and wilting, and plant stunting. |
Assure dense,
uniform stand; promote vigorous plant growth; do not plant near small grains. Base
insecticide treatment on 2 or more bugs on 20 percent of plants less than 1.25 cm high or
75 percent of plants infested. |
---------------------------- Insects pests of leaves and leaf whorls
---------------------------- |
| Corn
leaf aphid, Rhopalosiphum maidis (Fitch) |
Bluish-green
aphid is 1.5 mm long with black legs, antennae, and cornicles; winged and wingless forms
in colony. |
Sucks juice,
usually within the plant whorl; may cause yellow mottling of leaves; transmits maize dwarf
mosaic virus. |
Usually not
justified. Insect may be beneficial by increasing abundance of natural enemies. |
| Greenbug,
Schizaphis graminum (Rondani) |
Aphid is 1.6 mm
long and pale green with darker green dorsal abdominal stripe and black distal leg
segments and tips of cornicles; winged and wingless forms in colony. |
Sucks juice
from underside of leaves, injects toxin that causes red spots, yellowing and leaf death,
vectors virus, and predisposes plant to disease and lodging. Causes damage at any plant
growth stage. |
Resistant
hybrids; base insecticide treatment on extent of plant damage at different growth stages.
Biotypes exist to resistant hybrids and insecticide resistance. |
| Spider
mites, especially Banks grass mite, Oligonychus pratensis (Banks) |
Extremely
small, to 0.4 mm; color varies from green to yellow, with 2 darker spots on lateral
margins of back; palpi and first 2 pairs of the 8 legs are salmon colored. |
Sucks juices
from underside of leaves in webs; initial colonies along the midrib; leaves turn pale
yellow, later red, then brown. |
Often an
induced pest. Prevent plant moisture stress. Base insecticide treatment on 33 percent of
area of lower leaves infested; control is erratic. |
---------------------------- Insect pests of panicles
---------------------------- |
| Sorghum
midge, Stenodiplosis sorghicola (Coquillett) |
Adult is small,
2-mm-long, orange-red fly. Orange larva is cryptic within spikelet. |
Adult female
lays eggs in flowering spikelets; larval feeding on ovary prevents kernel development. |
Early, uniform
planting in region. Base first insecticide application on 1 adult per panicle at 25-30
percent flowering. |
| Corn
earworm, Helicoverpa zea (Boddie) |
Mature larva
38-50 mm long; varies from green, yellow, or pink to almost black, with fairly prominent
longitudinal lines; dark stripe divided by narrow white line looks doubled down back. |
On whorl-stage
sorghum, feeds in whorl on leaves that appear ragged after emerging. Most damaging when
feeds on developing kernels of panicle. |
Early planting
of hybrids with loose panicles. Base insecticide treatment on 2 small larvae per panicle. |
| Fall
armyworm, Spodoptera frugiperda (J. E. Smith) |
Mature larva 40
mm long, greenish to grayish brown, with light-colored inverted "Y"-shaped
suture on head and dorsal lines running lengthwise on body. |
On whorl-stage
sorghum, feeds in whorl on leaves that appear ragged after emerging. Most damaging when
feeds on developing kernels of panicle. |
Early planting
of hybrids with loose panicles. Base insecticide treatment on 2 small larvae per panicle. |
| Sorghum
webworm, Nola sorghiella Riley |
Mature larva 12
mm long; reddish to yellowish brown, flattened and marked with four longitudinal reddish
to black stripes; densely covered with hair. |
Larva feeds on
and chews circular holes in developing kernels of panicle. |
Early planting
of hybrids with loose panicles. Base insecticide treatment on 5 small larvae per panicle. |
| Rice
stink bug, Oebalus pugnax (Fabricius) |
Straw-colored,
shield-shaped bug 12 mm long. |
Sucks juices
from developing kernels causing them to be smaller, softer, and lighter weight than
nondamaged kernels; commonly, fungi infect damaged kernels causing them to be black. |
Usually less
abundant on early-planted sorghum. Base insecticide treatment on 5 bugs per panicle. |
| Southern
green stink bug, Nezara viridula (L.) |
Green bug 19 mm
long; typically shield-shaped. |
Sucks juices
from developing kernels causing them to be smaller, softer, and lighter weight than
nondamaged kernels; commonly, fungi infect damaged kernels causing them to be black. |
Usually less
abundant on early-planted sorghum. Base insecticide treatment on 4 bugs per panicle. |
| Conchuela,
Chlorochroa ligata (Say) |
Varies from
dull olive or ash gray to green, purplish, pink, or red brown; has orange-red band along
lateral margins of thorax and margins of wings and a spot of the same color on the back at
base of wings. |
Sucks juices
from developing kernels causing them to be smaller, softer, and lighter weight then
nondamaged kernels; commonly, fungi infect damaged kernels causing them to be black. |
Usually less
abundant on early-planted sorghum. Base insecticide treatment on 4 bugs per panicle. |
| Leaffooted
bug, Leptoglossus phyllopus (L.) |
Brown, oblong,
with white band extending across forewings; 20 mm long; tibiae of hind legs dilated or
leaf-like. |
Sucks juices
from developing kernels causing them to be smaller, softer, and lighter weight then
nondamaged kernels; commonly, fungi infect damaged kernels causing them to be black. |
ETL is six bugs
per panicle. Usually less abundant on early-planted sorghum. |
| False
chinch bug, Nysius raphanus Howard |
Bugs 9 mm long,
mottled gray. |
Sucks juices
from developing kernels causing them to be smaller, softer, and lighter weight then
nondamaged kernels; commonly, fungi infect damaged kernels causing them to be black. |
Usually clumped
on panicles and in areas in a field. Usually less abundant on early-planted sorghum. Base
insecticide treatment on 140 bugs per panicle. |
----------------------------
Insect pests of stalks ---------------------------- |
| Sugarcane
borer, Diatraea saccharalis (Fabricius); neotropical borer,
D. lineolatus (Walker); southwestern corn borer, D.
grandiosella Dyar; Mexican rice borer, Eoreuma loftini (Dyar) |
Mature larva 25
mm long; creamy white and marked with brown to black spots. |
Larva bores
into stalk; may cause reduced stalk diameter, deadheart, or lodging. |
Early planting;
stubble destruction; good cultural management; insecticide usually not required. |
