Brown stink bug, Euschistus servus
Lesser brown stink bug, Euschistus spp.
Conchuela stink bug, Chlorochroa ligata
Green stink bug, Acrostermnum hilare
Southern green stink bug, Nezara viridula
Harlequin bug, Murgantia histrionica
Description. Several species of stink bugs feed on cotton fruit in Texas cotton. In South and East Texas, the primary stink bug species is the southern green stink bug, followed by the green stink bug and brown stink bug. In West Texas and the Winter Garden, the conchuela stink bug is most prominent.
Stink bugs are shield-shaped, flat and vary in size around 3/8 to 5/8-inch in length, and are about one-half as wide as their length. While the adult brown stink bug is light brown in color, the green and southern green stink bugs are bright green and similar in appearance. They can be distinguished from one another by color of the bands on their antennae. The southern green stink bug has red bands while the green stink bug has black bands. The conchuela stink bug adult is dark brown to black with a red border and a red spot on the tip of the abdomen. The harlequin bug is primarily a pest of mustards and cole crops will occasionally attack cotton. Adult stink bugs may live for several weeks. Stink bugs get their name from the foul smelling substance they exude from glands on their thorax. This chemical smell is meant to deter predators and warn other stink bugs of danger. This scent gland also plays a role in females attracting mates.
A single female may lay 300 to 600 eggs, laid in clusters of 30 to 80 eggs. Egg clusters appear as rows of pale-green, pink or white barrels laid primarily on the underside of leaves. Eggs will typically hatch in 2 to 4 days under ideal conditions, but may require up 2 weeks when temperatures are cool. Because the eggs are laid in clusters, stink bug nymphs are often found aggregated together in high numbers.
The immature stage of the stink bug is similar to the adult in shape but lacks wings. First instars of the southern green stinkbug are reddish orange, second instars are black with white spots, and third and fourth instars are black or dark green with pink and white spots. Additionally, southern green stink bug nymphs have two rows of spots on the back of their abdominal segments. Early instar green stink bugs begin as reddish brown in color, but turn light green with black and white stripes as they mature. The white stripes tend to turn yellow as they mature and there is a single row of spots on the back in third and fourth instar green stink bugs. The conchuela stink bug nymphs are similar to its adult in color. Immature stink bugs will pass through 5 instars, each lasting 5 to 7 days. The entire life cycle from egg to adult typically requires 40 to 45 days.
In Texas, stink bugs will produce up to 5 generations per year in the southern portions of the state, but there may be as few as 2 generations in more northern areas. Stink bugs will overwinter in just about any habitat that provides cover and protection from the environment. Favored places include thick grassy areas, under rocks and logs, and brushy environments. When temperatures reach 70 degrees F, overwintering adult stink bugs will emerge and begin feeding and laying eggs. The first generation usually occurs on wild hosts near the overwintering site. For conchuela stink bugs this is usually in mesquite where they feed on mesquite beans. Subsequent generations may disperse into field crops such as soybeans, corn, sorghum and cotton.
Damage. Stink bugs have piercing-sucking mouthparts and damage cotton by piercing bolls and feeding on the developing seeds. Their feeding activity usually causes small bolls to abort but can result in dark spots about 1/16-inch in diameter on the outside of larger bolls where feeding occurred. (These dark spots do not correlate well with the wart formation on the inside of the boll to be used in scouting.) There may be several spots on a boll without internal feeding.) The external lesions are associated with wart like growths on the inner carpal wall where penetration occurred. Seed feeding may result in reduced lint production and stained lint near the feeding site. Stink bugs are also known to facilitate the infection of boll rotting organisms. Because of their size, adults and fourth and fifth instar nymphs have the greatest potential for damaging bolls.
Management and decision making.
Cultural management. There are not many cultural practices that will aid in managing stink bugs in cotton, although knowing what sorts of habitats stink bugs may disperse from may be useful in predicting infestations. Thus it can be advantageous to monitor nearby crops and weedy habitat for the presence of stink bugs as a predictive measure.
Biological control. There are a number of parasites that prey on stink bugs. All life stages (egg, nymph and adults) can be parasitized. Generalist predators are also important for biological control of stink bugs. The red imported fire ant is considered an important stink bug predator. The beneficial impact from most parasites and predators of stink bugs occurs in non-crop habitats.
Scouting. Stink bugs are difficult to detect, especially in tall, rank cotton. Stink bugs can be seen climbing about the cotton early in the morning before late morning heat, or by utilizing a sweep net, but because they can be distributed throughout the canopy, the recommended sampling technique is to use a drop cloth. Refer to page ?? for a detailed description of sampling techniques. When using a drop cloth take 4 to 6 samples from 4 to 6 locations throughout the field, paying particular attention to field margins, especially near stink bug sources.
Recent research indicates that decisions to treat for stink bug infestations may be best made based on boll damage. To use this technique remove 25 bolls, one 1-inch in diameter, from each of four parts of the field. Cut these bolls open and examine the interior carpal wall for wart like growths or staining.
Once the cotton has reached 450 DD60s beyond cutout (5 nodes above white flower), sampling and treating for stink bugs may no longer be necessary since bolls produced after this point will not fully mature or contribute significantly to yield. However, it is possible that this value may shift slightly due to factors such as water stress, variety, and boll shading.
Chemical control and action threshold. The action threshold for stink bugs based on the drop cloth sampling techniques is when stink bugs are averaging at least one per 6 row-ft. Treatment is also recommended, based on boll sampling, when 20% or more of the bolls have internal wart and/or stained lint and stink bugs are present. Some resistance to pyrethroids has been documented in brown stink bug populations of the Coastal Bend of Texas. Southern Green, Green and conchuela stink bugs can be controlled with recommended insecticides.
|Stink Bug Action Threshold|
|Drop cloth||Boll sampling|
|1 or more per 6 row-ft||Presence of stink bugs with 20% or more bolls with warts on inner carpal walls and/or stained lint|
|Cease sampling and treating when NAWF = 5 + 450 DD60’s|
|Suggested Insecticides and Rates for Managing Stink Bugs in Cotton
ingredient per acre
|Amount of formulated
|Acres treated per gal or lb of
|Mode of Action Group (IRAC)|
|Brown stink bugs only|
Acephate 90, generics)
(Bidrin 8 )
|0.25-0.5||4-8 fl oz||32-16||1B|
4-6.4 fl oz
(Methyl 4EC, generics)
(Vydate C-LV 3.77)
|0.33-0.5||11.2-17 fl oz||11.4-7.5||1A|
|All stink bugs excluding brown stink bugs(products listed above for brown stink bug should also be effective)|
(Baythroid XL 1)
|0.013-0.02||1.6-2.6 fl oz||80-49.2||3A|
(Brigade 2, generics)
|0.04-0.10||2.6-6.4 fl oz||49.2-20||3A|
|—||3.8-7.7 fl oz||33.7-16.6||3A, 4A|
(Leverage 2.6 SE)
|—||3.8-5 fl oz||33.7-25.6||3A, 4A|
(Bidrin 8 )
|0.5||8 fl oz||16||1B|
(Declare 1.25, generics)
|0.01-0.015||1.02-1.54 fl oz||125.5-83.1||3A|
(Karate 1 EC, generics)
|—||3.5-5.5 fl oz||36.6-23.3||3A, 4A|
(Mustang Max 0.8 E)
|0.018-0.025||2.8-4 fl oz||45.7-32||3A|
(Hero 1.24 EC)
|—||10.3 fl oz||12.4||3A|
1rates vary depending on formulation.