CENTRE COUNTY - An invasive bug, known as the brown marmorated stink bug, has graduated from being a nuisance in people's homes to an agronomic concern, according to Steve Jacobs, extension entomologist at Penn State's College of Agricultural Sciences.
During a recent presentation at Ag Progress Days, Jacobs spoke to an audience about the invasive insect and how it is affecting farmers and their crops.
"You will probably walk out of here with more questions than answers," he said.
PHOTO COURTESY OF STEVE JACOBS/PSU ENTOMOLOGY
The brown marmorated stink bug, an invasive species, is pestering homeowners and destroying farmers’ crops, say experts with the Penn State College of Agricultural Sciences.
He means that, even though the bug first was found in Pennsylvania in 1998 in Allentown, experts still are learning about it.
The BMSB, as it is commonly called, hails from the Orient - countries such as Japan, China, Korea and Taiwan.
"This thing is jumping around all over the place," Jacobs said, referring to its dispersal across the Mid-Atlantic region.
Because of the massive amount of commerce the United States has with those countries, it is common to find invasive bugs, such as the BMSB, in the U.S.
Attack on the crops
"The real problem is with fruits," Jacobs said.
Last year, he said, many farmers had to dump their crops because of stink bug damage.
The bugs attacks fruit such as peaches, apples and citrus. They leave cork-like marks and brown spots on the fruit and under the skin. This makes the fruit un-marketable.
A fact sheet by Penn State Cooperative Extension said insects in neighboring states often are found feeding on tomatoes, lima beans and green peppers. Jacobs said they insert a mouth-like body part into the fruit, inject their saliva and suck out the juices.
According to the U.S. Apple Association, apple growers last year experienced more than $37 million in damages from the BMSB.
Jacobs said last year orchards were taking their stink bug damaged apple crop to be pressed into cider, since the apples were not marketable.
Even though some orchards are sprayed daily for the bug, it's not helping.
"I actually had a dairy farmer tell me that he had cows who refused (to eat) silage which had stink bugs in it," he said.
Soybeans, which are not native to the U.S. but are widely grown in Pennsylvania, also are a favorite food for BMSB. Jacobs said a farmer reported to him that he saw large numbers of the bug in his soybean crop last year.
Another concern of experts and crop growers for this year is how the BMSB affecting the corn crop.
"They are big in numbers in sweet corn right now," Jacobs said.
Field corn doesn't escape the stink bug. Corn will show browning and shriveling on the cob in the field.
The bugs started out as a nuisance to homeowners who found them attached to the outside of their homes or coming through small cracks or open areas into their houses.
Learning and combating
Jacobs said Penn State's College of Agricultural Sciences, along with other institutions, want to figure out what exactly attracts the stink bug to homes and to fields of crops, how to monitor their spread and how to battle them.
"I have seen very few plants these guys won't attack," he said.
He told the audience that stink bugs do like plants from their native countries, which are known as ornamentals here. Many are used for landscaping and decorative purposes.
Experts use a pheromone to trap the bugs and study their range.
Penn State Extension tree-fruit entomologist Greg Krawczyk, received a grant of $50,000 in March from the Pennsylvania Apple Marketing Board to i a two-year investigation into problems being caused by the BMSB, according to Penn State.
In the fall, the insect begins to look for overwintering sites and will come indoors to do so. It will emerge in the spring.
Homeowners should take extra precautions to make sure their houses are well sealed. Caulk cracks and repair holes in door and window screens.
Jacobs does not recommend using pesticide sprays on the insects.
Pennsylvania has four native stink bug species, but it is the invasive brown marmorated stink bug that is causing the widespread crop damage, he said.
The BMSB can be various shades of brown. An adult is about 3/4-inch long and is about the same distance wide.
It has the distinct shield-shape as do other stink bugs. The brown marmorated stink bug's eggs can elliptical-shaped and laid in clusters of 20 to 30 on the undersides of plant leaves, Jacobs said.
The bugs do smell, as the other species do. One audience member said he thought they smell like a musky basement. Jacobs said it reminds him of the smell of cilantro.
The biggest problem with the BMSB is there are no known natural predators here to help keep the population in check.
One type of predatory wasp will lay its eggs on BMSB eggs and destroy then, but Jacobs said that only puts a 2 percent to 5 percent dent in the population of the BMBS.
Other predators can include birds, spiders and praying mantises, but that still isn't enough to combat the invasive species, the experts say.
Pennsylvania is likely into its second generation of the bug. Jacobs said the bug may be a little behind in reproducing this year because of the cool, wet spring - but it is catching up.
The invasive species also may spread through the state and nation by hitchhiking in recreational vehicles and other automobiles.