The brown marmorated stink bug, a recently found invasive species in Kentucky, continues to increase in numbers in our area. It has a wide host range of vegetable and fruit crops. Currently, sweet corn is on the radar as a crop with the potential for rising pest populations.
Stink bugs are attracted to sweet corn as it moves into the milk stage of ear development. Sweet corn tends to also be a favorite crop for the development of immature (nymph stage) BMSB. Both the nymphs and adults penetrate through the husk leaves of ears to feed on developing kernels with their piercing-sucking mouthparts. This results in shriveled and partially shriveled kernels that can turn brown. When numbers are high, BMSB have the ability to ruin a crop.
As with corn earworm, planting date is very important; sweet corn that matures in early July is likely to be harvest before BMSB populations are at their highest. However, sweet corn maturing in late July and August may be more likely to have issues with BMSB. Sweet corn maturing later in September may have less risk to BMSB.
In terms of insecticidal control, treat if substantial numbers are found on the husk leaves of ears. There are no preventive treatments and the Bt sweet corn hybrids have no resistance to stink bugs. If an insecticide is needed, one of the pyrethroids listed for corn should be used.
Similar to stink bugs, leaf-footed bugs are becoming common late-season pests of tomatoes, green beans, and peppers. They feed with piercing-sucking mouthparts on the fruiting portion of plants. The adults produce damage very similar to that of stink bugs. This appears as corky damage under the fruit skin of peppers and tomatoes and as sunken areas on green bean pods.
Leaf-footed bugs are large, about 1 inch in length, and relatively narrow when compared to a stink bug. While their body shape and color are similar to that of a squash bug, their hind legs have a flattened and expanded tibia that is the basis for their common name. Leaf-footed bugs may also be confused with assassin bugs, which are beneficial as insect predators, but assassin bugs usually have enlarged front legs to capture and hold prey.
Occasionally, leaf-footed bugs may need to be controlled, particularly on tomatoes where they cause cloud spots under the skin similar to stink bugs. Pyrethroid insecticides are a good choice for garden pests. Be sure to read and follow the label.
Kelly R. Jackson is the Christian County Extension Agent for horticulture. He can be reached at 270-886-6328 or visit Christian County Horticulture online at www.christiancountyextension.com.