Stink bugs, Hemiptera: Pentatomidae

Description

Several stink bugs including the brown stink bug, the green stink bug, the southern stink bug and the rice stink bug occur on grain sorghum in Arkansas. Stink bugs are true bugs having the front half of the fore wing hardened while the rear portion is membranous. Adults are about ½ inch long and color varies from tan to green depending on species (Photo 11). Immature stink bugs or nymphs resemble the adults but are wingless.

Distribution, damage and impact

Stink bugs occur throughout Arkansas and impact grain sorghum production by feeding during early stages of seed formation. Soft seed is fed on by the bug inserting its stylet or beak into the seed and withdrawing partially digested plant material (Photo 12). After the seed hardens damage from stink bugs is minimal.

Life History

Stink bugs overwinter as adults in plant debris located on field boarders. In late winter or spring when temperatures approach 70 degrees adults become active, mate and females begin to deposit eggs. Each female can deposit several hundred eggs on weed hosts. Nymphs emerge and feed on alternate hosts and cultivated plants for over one month before they form wings and disperse. In Arkansas several generations are produced each year. Populations can build to high levels in late summer and fall. Grain sorghum in early stages of head formation can sustain considerable damage during this period.

Management

Destruction of overwintering sites may play a role in stink bug population development. Because adult bugs are strong flyers, however, this practice may have little benefit. The most practical management tactic is use of foliar insecticides. Fields should be scouted for adult and immature stink bugs from flowering to maturity. Because of the clumped distribution of stink bug populations, efforts to scout entire fields should be undertaken. A minimum of 30 sorghum heads should be shaken into a white bucket and the stink bugs should be counted. The recommended threshold in Arkansas is 5 stink bugs per sorghum head. As seed mature this number should be greatly increased, i.e., 16. Numerous beneficial organisms affect stink bug populations including some beneficial stink bugs and insecticide use may reduce their effectiveness.

Insecticide recommendations for stink bugs on grain sorghum

See Table 2 for insecticide recommendations current at time of publishing. Current updated recommendations can be found in the Cooperative Extension Service publication MP-144 and on the world wide web at WWW.cdms.net/manuf/default.asp. Always follow instructions on pesticide labels.