Stink bugs are coming: Invasive species have few natural predators in Maryland

By Amanda Stout, Entomological Sciences Division lab manager, Defense Health Agency-Public Health Have you noticed the temperature starting to rise? Have you started to notice those pesky, stinky, brown bugs throughout your home, barracks, in your workspace, or outside on post? Crawling out of dark spaces and emitting an unpleasant smell, stink bugs are emerging from diapause.

Brown Invader Most people think that this brown invader, dubbed the Brown Marmorated Stink Bug, or BMSB, is the only stink bug around, but this invasive species is one of many that call the state of Maryland and Aberdeen Proving Ground home.

Native species can range from bright green to vibrant reds and blacks and even produce zebra-striped eggs. Jonathan Schmude, a biological science technician with the United States Department of Agriculture Agricultural Research Service says, “It’s always sad to me when people say they hate stink bugs because they only know and see BMSB. Meanwhile there are many beautiful and environmentally significant and less stinky native species that people can enjoy if they take the time to look.”

Impact to environment Native species of stink bugs are not as widely known because they are more adapted to survive on local plants and tend to hide among wild fruit, grasses, and trees. Some natives, such as the spined soldier bug, help home gardens by eating beetle and lepidopteran larvae that cause damage to crops. Others produce feeding damage to plants, making the plants more accessible for other native insects to consume.

“BMSB is so well known because of the significant crop damage it causes on apples, beans, corn, and other fruits and vegetables that we eat,” Schmude explains. “It’s not that native stink bugs don’t do some damage to these crops, but for the most part they rely on fruits and vegetation that humans rarely or never eat, such as wild blackberries, autumn olive, and pokeweed.”

BMSB Predators BMSB is also more well known because its population is minimally controlled by native predators, and there are few pesticides that are effective against it, said Schmude. Native stink bug predators are usually small wasps, the size of an ant, that typically sting the stink bug egg and lay their own egg inside. To combat BMSB, researchers traveled to Asia and collected parasitic wasps from there to be tested as a potential biological control agent. One of the wasps collected was the samurai wasp (Trissolcus japonicus), which is very effective at controlling BMSB in its home range. The wasp was extensively tested in labs across North America to determine its effect on native populations of stink bugs. In 2014, Trissolcus was found to have traveled to North America on its own and has subsequently established itself as an effective control agent for BMSB.

“The samurai wasp showed minimal effect on native stink bug species in the lab, but you may have noticed the significant drop in BMSB in the past few years,” said Schmude. “This is, in part, due to the diligence of this wasp.”

BMSB Risk Service members and their families may still experience plenty of BMSB in their homes and may worry about children and pets being affected, said Schmude. If consumed, any stink bug can produce a stinging and burning sensation in the mouth that can last for several hours. Although not poisonous, the emitted smelly chemicals can cause mental anguish and physical discomfort in both pets and people. Stink bugs can also stain skin and emit an unpleasant odor onto fabrics, air, and clothing.

Prevention The best way to prevent stink bugs from coming into your home is to minimize potential entry points. Make sure all window screens are sealed with caulk and are without holes, and ensure there is proper weatherstripping on all doors. Perform a cleaning in fall, when stink bugs are looking for a spot to overwinter, such as in dark and less frequently used spaces like garages, attics, and mud rooms. Clear debris from doorways and under windows where stink bugs also like to hide.

If you notice an abundance of stink bugs in any part of your home or workspace, set up a pan trap. Simply take a foil baking dish, fill it with a ratio of two cups of water, one cup white vinegar, and a half cup of dish soap.

“The vinegar helps attract any stink bugs that may be inside, and the soap decreases water tension so when the stink bugs land, they sink under the surface of the water,” said Schmude.

As the weather continues to warm up, keep an eye out for BMSB and take a moment to catch a glimpse of one of the beneficial and beautiful native species that call Aberdeen Proving Ground home.

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