Garden Variety: Stinkbugs damage plants, remain pesky for gardeners
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Stinkbugs are dime-sized, shield-shaped, green and brown insects that damage fruits, vegetables and other desirable plants when they feed on them. The insects are prevalent in gardens right now in northeastern Kansas and will be around until freezing temperatures arrive.
Damage to fruits, vegetables and other plants occurs when stinkbugs insert their proboscis (straw-like mouthparts) into plant tissues and suck juice out of them. This feeding leaves a small brown spot with a white halo that may appear sunken or swollen. With a lot of feeding, fruit becomes deformed and ripens unevenly. On leaves and stems, stinkbug feeding can lead to abnormal growth and plant stress that results in delayed or reduced yields.
Tomatoes and soybeans are stinkbug favorites, but the insects are also major pests of blackberries, peppers, eggplants, peaches, plums, apples, pears, sunflowers, corn and other soft-skinned vegetables and fruits.
In Kansas, green stinkbugs and brown stinkbugs are most common. The color is more than a descriptor — it is part of each of these two species’ common names. Green stinkbugs are the largest with bodies that are about a half-inch long at maturity. Adult green stinkbugs are chartreuse-lime colored. Brown stinkbugs are a little smaller at maturity and are dark brown to gray with gray to black speckling on their backs.
Like other stinkbugs, green and brown stinkbugs are shaped like a shield. They are very closely related to squash bugs, which have a similar shape but are more elongated. Stink bugs get their name because of scent glands that release a foul odor when the insects feel threatened. The scent is a protective measure that makes them less attractive to predators.
In small gardens, the most effective method of control is to pick stinkbugs off of plants when seen and drop them into a jar of soapy water or otherwise dispose of them. For larger gardens with heavy populations of stink bugs, gardeners may opt for kaolin clay (product name Surround), which has shown some success as an organic option. Conventional insecticides are less effective because they need to be reapplied and stinkbugs can easily move on or avoid sprayed plants.
Green and brown stinkbugs produce two to four generations from midsummer to fall in the Midwest.
Gardeners should also be on the lookout for brown marmorated stink bug (BMSB). This species was introduced into the eastern U.S. in the 1990s and has been a major pest in fruit and vegetable production in that part of the country. The insect has been confirmed in Kansas but only as an isolated individual. It is very hard to tell apart from the more common brown stinkbug and closely related dusky stinkbug and rough stinkbug.
Birds are a natural predator of stinkbugs. Creating habitat that is desirable for birds near your garden may help to reduce populations of unwanted insects.
— Jennifer Smith is a former horticulture extension agent for K-State Research and Extension and horticulturist for Lawrence Parks and Recreation.