There are several economically important insects that must be considered to help produce a corn crop with high yield potential. One pest that has increased in frequency is the brown stink bug (BSB) (Figure 1). Knowing how to distinguish BSB from other stink bugs and its feeding practices on seedlings and maturing corn is important.
Brown stink bugs can be found early in the season compared to green stink bugs because the BSB overwinters in northern climates, while the green stink bug migrates to northern climates during the growing season. In practice, we tend to see the green stink bug during reproductive stages in the Midwest and the BSB all season. The BSB overwinters as an adult in fence rows and heavy residue. In the spring, they may look for early planted corn and are usually found on field margins or around grass patches that may have been controlled with herbicide. The introduction of cover crop grasses in the cropping rotation, such as cereal rye, may increase the level of BSBs that can be found in corn fields. Adult female stink bugs lay eggs (20-30) that resemble small silos. When the young hatch, they look like miniature adult stink bugs.
Brown stink bugs can cause stand reductions, barren ears, spindly plants and deformed kernels. In V1 to V4 corn growth stages, the bugs stick their piercing mouth part (Figure 2) into the base of the seedling near the growing point and inject an enzyme that allows them to extract nutrients from the plant. The injury appears much like a growth regulator herbicide injury symptom on the plant. Tillers or suckers develop because the growing point of the original plant is damaged. The loss of the original plant effectively terminates the potential to produce a normal ear. Ragged leaves and twisted tops are also common from seedling and early growth feeding. If scouting determines damage to be at an economical stage, a foliar insecticide application may be warranted. Prior to planting corn, if the field to be planted has a grassy cover crop, the addition of an insecticide to the burndown herbicide may be warranted to help control BSBs.
Should feeding occur when the ears are developing, the ear becomes the feeding target. Individual kernels are pierced and drained through the husk (Figure 3). A foliar insecticide applied at tasseling (VT growth stage) is the only potential control tactic for reproductive stage corn.
Stink bug management. 2017. Agronomy Advice. Channel.com. https://www.channel.com/agronomics/Documents/AgronomicContentPDF/StinkBugManagement.pdf
Early growth stage damage from stink bugs in corn. 2017. https://www.channel.com/agronomics/Documents/AgronomicContentPDF/EarlyGrowthStageDamagefromStinkBugsinCorn.pdf