What They Are
The brown marmorated stinkbug is a pest that was accidentally imported into the United States from Asia (possibly on packing crates). The bug began severely invading Maryland in the summer of 2010. "It was really a population gain like any insect," says Steve Allgeier, master gardener coordinator for University of Maryland Extension. "In some cases, it never builds up because of predators and disease." However, the stinkbug did persist and has become a severe pest. Females typically lay 28 eggs per clutch, which occurs in the warmest months.
What They Do
Right after they hatch, stinkbugs start feeding, mostly on their favorite crop, tree fruits. While a common misconception is that stinkbugs chew plants apart, they actually have piercing mouthparts that harpoon into food and extract nutrients. "They tend to be dirty feeders, like junkies with syringes," Allgeier says. "They pass around fungi and yeasts from plant to plant. This causes internal rot on crops." Many farmers will pick these fruits, not detect surface damage, but then eventually have to sell them to markets for a reduced price. Allgeier predicts that stinkbug damage will eventually lead to higher food costs.
Where To Find Them
While stinkbugs are now present in 33 states, the East Coast was the most heavily invaded, and Maryland is at the epicenter. There are some orchards on the Maryland panhandle that have recorded an 80-percent loss in tree fruit. The bugs also prefer corn and soybeans, which are primary Maryland crops. Stink bugs especially love apples, tomatoes, peaches, and pears. But, tracking the bugs down can prove difficult. "This is a very hit-and-run type feeder," Allgeier says. "They will spend some time outside in the garden, quickly feed, then leave." This makes the stinkbug even more difficult to eliminate.
How To Control Them
Allgeier points out that, because this pest is new, scientists are still in the experimental phase when it comes to managing stinkbugs. "We know that we won't be able to spray our way out of this problem," he says, referring to chemical pesticides. "Since they're hard to locate, they're hard to spray." But he does say there are ways to protect your garden, like floating row covers, which are pieces of gauzy fabric that you can drape over plants like a tent. However, this can block out necessary insects and cause a greenhouse effect. He also recommends buying insecticidal soap from a local gardening store and releasing that through a hose sprayer.
What Researchers Are Doing
At University of Delaware, scientists are studying a parasitic wasp that keeps stinkbugs under control in Asia. But researchers must determine whether it's safe to release the wasp here. There are also labs testing pesticides, but Allgeier warns that this is a contentious issue. "Many of the older insecticides are effective, but agriculture is trying to move away from them," he says. He adds that stinkbugs are a long-term issue. "It will be about five years before the wasps could even be released," he says. "For now, stinkbugs are here to stay."