Photograph by Jeff Hertrick, National Geographic
These tiny wasps could prey on stinkbugs. Photograph courtesy Brian Thomas Cutting
Published March 1, 2013
Maryland farmer Nathan Milburn recalls his first encounter.
It was before dawn one morning in summer 2010, and he was at a gas station near his farm, fueling up for the day. Glancing at the light above the pump, something caught his eye.
"Thousands of something," Milburn remembers.
Though he'd never actually seen a brown marmorated stinkbug, Milburn knew exactly what he was looking at. He'd heard the stories.
This was a swarm of them—the invasive bugs from Asia that had been devouring local crops.
"My heart sank to my stomach," Milburn says.
Nearly three years later, the Asian stinkbug, commonly called the brown marmorated stinkbug, has become a serious threat to many mid-Atlantic farmers' livelihoods.
The bugs have also become a nuisance to many Americans who simply have warm homes—favored retreats of the bugs during cold months, when they go into a dormant state known as overwintering.
The worst summer for the bugs so far in the U.S. was 2010, but 2013 could be shaping up to be another bad year. Scientists estimate that 60 percent more stinkbugs are hunkered down indoors and in the natural landscape now than they were at this time last year in the mid-Atlantic region.
Once temperatures begin to rise, they'll head outside in search of mates and food. This is what farmers are dreading, as the Asian stinkbug is notorious for gorging on more than a half dozen North American crops, from peaches to peppers.
The first stinkbugs probably arrived in the U.S. by hitching a ride with a shipment of imported products from Asia in the late 1990s. Not long after that, they were spotted in Allentown, Pennsylvania. Since then, they've been identified in 39 other states. Effective monitoring tools are being developed to help researchers detect regional patterns.
There are two main reasons to fear this invader, whose popular name comes from the pungent odor it releases when squashed. It can be distinguished from the native stinkbug by white stripes on its antennae and a mottled appearance on its abdomen. (The native stinkbug can also cause damage but its population number is too low for it to have a significant impact.)
For one thing, Asian stinkbugs have an insatiable appetite for fruits and vegetables, latching onto them with a needlelike probe before breaking down their flesh and sucking out juice until all that's left is a mangled mess.
Peaches, apples, peppers, soybeans, tomatoes, and grapes are among their favorite crops, said Tracy Leskey, a research entomologist leading a USDA-funded team dedicated to stinkbug management. She adds that in 2010, the insects caused $37 million in damage just to apple crops in the mid-Atlantic region.
Another fear factor: Although the stinkbug has some natural predators in the U.S., those predators can't keep up with the size of the stinkbug population, giving it the almost completely unchecked freedom to eat, reproduce, and flourish.
Almost completely unchecked. Leskey and her team have found that stinkbugs are attracted to blue, black, and white light, and to certain pheromones. Pheromone lures have been used with some success in stinkbug traps, but the method hasn't yet been evaluated for catching the bugs in large numbers.
So Milburn—who is on the stakeholders' advisory panel of Leskey's USDA-funded team—and other farmers have had to resort to using some chemical agents to protect against stinkbug sabotage.
It's a solution that Milburn isn't happy about. "We have to be careful—this is people's food. My family eats our apples, too," he says. "We have to engage and defeat with an environmentally safe and economically feasible solution."
Research Entomologist Kim Hoelmer agrees but knows that foregoing pesticides in the face of the stinkbug threat is easier said than done.
Hoelmer works on the USDA stinkbug management team's biological control program. For the past eight years, he's been monitoring the spread of the brown marmorated stinkbug with an eye toward containing it.
"We first looked to see if native natural enemies were going to provide sufficient levels of control," he says. "Once we decided that wasn't going to happen, we began to evaluate Asian natural enemies to help out."
Enter Trissolcus, a tiny, parasitic wasp from Asia that thrives on destroying brown marmorated stinkbugs and in its natural habitat has kept them from becoming the extreme pests they are in the U.S.
When a female wasp happens upon a cluster of stinkbug eggs, she will lay her own eggs inside them. As the larval wasp develops, it feeds on its host—the stinkbug egg—until there's nothing left. Most insects have natural enemies that prey upon or parasitize them in this way, said Hoelmer, calling it "part of the balance of nature."
In a quarantine lab in Newark, Delaware, Hoelmer has been evaluating the pros and cons of allowing Trissolcus out into the open in the U.S. It's certainly a cost-effective approach.
"Once introduced, the wasps will spread and reproduce all by themselves without the need to continually reintroduce them," he says.
And these wasps will not hurt humans. "Entomologists already know from extensive research worldwide that Trissolcus wasps only attack and develop in stinkbug eggs," Hoelmer says. "There is no possibility of them biting or stinging animals or humans or feeding on plants or otherwise becoming a pest themselves."
But there is a potential downside: the chance the wasp could go after one or more of North America's native stinkbugs and other insects.
"We do not want to cause harm to nontarget species," Hoelmer says. "That's why the host range of the Asian Trissolcus is being studied in the Newark laboratory before a request is made to release it."
Ultimately, the USDA's Animal and Plant Health Inspection Service will decide whether or not to introduce the wasp. If it does, the new natural enemy could be let loose as early as next year.
Do you have stinkbugs in your area? Have they invaded your home this winter? Or your garden last summer? How do you combat them? Share your sightings and stories in the comments.
Reading the responses I know I've been lucky so far. But the extend of other's invasion alerts me to the importance of working on controlling them when their numbers are few.
I found some inside my home in the past month. Before that I found numerous one on my 6' long row of a mixture of domestic black berries and Marion berries. If we ate a berry we found one on, the berry would have a very bitter taste. This is in Salem, Marion, Oregon.
Two years earlier I found them in Dallas, Polk, Oregon in a tree I was pruning on a family member's property. The tree is a Hawthorne with a red blossom.
They have to take action before it's too late.
Some kind of chemical treatment will do the work
I live in southeastern Pennsylvania and there are so many on the outside of our house that the walls look like they are moving. We had a lock-top damper put on our chimney and that keeps them from getting into the house from the fireplace. We use the soda bottle traps in the attic and that catches hundreds of them over the winter. When the traps get full, we suck them into a shop vac that has insecticide in the tank. We use that same shop vac to vacuum hundreds of them from our outside porches each day in October. Releasing any that are vacuumed up or caught in traps just adds to the population. I'm hoping the wasps are released soon.
We've been doing battle with these bugs for the past two autumns. We've used exterminators and used various insecticides on our own with little or no results. They can literally cover a window when the weather warms up. We live in northern WV, bordering PA.
Premethrin is an excellent garden spray (use as directed) to eradicate these pests. Malathion works, too, but premethrin studies show it to be safest/best.
I just caught a Stink bug in my home, on the second floor, this is the third year in a row, the first year was in the winter, I thought it was something that I brought back from the Caribbean and have been wondering about it. Finally tonight I have been able to identify it. The nearest thing to a fruit tree are dogwood trees in the yard. What could they be eating around my home? I live on Long Island.
I can't stand these pests. I live in Delaware not to far from Newark and would be very interested to know more about these wasps. Just on Saturday night while dyeing Easter eggs with my daughter, one decided to take a swim in her purple dye. You should have heard my daughter cry. I have tried the traps but they did not work for me. I too would like to know what these pests feed on while in my home. I have no house plants and no fruit sitting out. I hope we find a solution soon.
One found it's way into my apartment (Staten Island, NY) in January. It was buzzing around my hallway light - and I'd never seen them fly before. I see a few every year, but usually in summer, not winter.
We just killed a stinkbug 3/2/2013 they are starting to come out now! Last year they were bad and are hard to kill! Killed everyone we saw!
They were nowhere near as bad at my home in 2012 as they were in 2011. I only had a handful coming in the house this fall where the year before there were hundreds. Nothing is cute by the hundreds.
I am sorry, but I think these critters are cute. I usually have them land on the lamp on my night table as I am reading at bed time. They wobble around slowly like drunken little elephants. They don't mind handling and they are fascinating to look at. It's like having a temporary pet, then I let them out the window.
But all my sympathy to the farmers. Pests are pests even if they are cute.
Thanks for sharing your stories, everyone! I'm grateful that I haven't had to contend with many stinkbugs in my DC apartment, but I've been exposed to plenty of them at my husband's uncle's cabin near Frederick, Maryland. Please tune in on Monday at 3:00 for a live Twitter chat. We want your questions--and of course your sightings! I'll be there, as will producer Jeff Hertrick and stinkbug maven Tracy Leskey. #NatGeoLive
I've seen these things multiply with staggering speed in the Blue Ridge mountains of Virginia since 2007. Here's a guide to build the most effective trap I've seen in action.
What you'll need:
light source, tape, 2 liter bottle.
I live in the Eastern Panhandle of West Virginia, and it seems like this could be a bad year, based on the number I'm seeing inside the house. They've completely ruined my peach and Asian pear crops on my trees. They can also do damage to some house plants. They like to perch on orchids, ficus, palms, violets- literally anything green. To get rid of them, I suck them up with a vacuum that has an enclosed catch bag. They never get out! They maneuver inside through window casings and door frames. They hover in between the rubber insulation. I've sucked up dozens from one door. Join us Monday at 3pm ET for a live Twitter chat about stink bugs with author Catherine Zuckerman. #NatGeoLive
Ive seen them already since it's getting warmer here in PA! I use a trap that seems to work... http://www.lowes.com/pd_129205-2226-1SBTR_0__?productId=3433974
We live not far from Nathan Milburn, and I have seen evidence already that this year may be as bad as 2010. Because we do not have air conditioning and our house remains open during the warm months, thousands of stink bugs seek refuge in our house in September, swarming on the southern side. They must seek warmth in our attic, and now on warm days, they crawl through the light fixtures into the house at an alarming rate. I am committed to eradicating as many as I can by throwing them in the fire, flushing them or feeding them to my chickens, but I despair that this year will be truly Biblical in proportions. At first I did not notice much damage in my garden, but last year there was damage both to my grapes and tomatoes.
We have had stinkbugs ever since we bought our house in 2009, 2010 was definitely the worst time for them though. We must have had literally hundreds in our house during that fall. I just suck them up in the vacuum and empty the contents outside, however, if you get a female (the stinky ones) then the stink goes all over the house, its awful. I did notice that last summer they were quite attracted to our bug zapper, maybe due to the blue light, but didn't see that many during the summer to be honest. I hope they come up with a trap that works soon, these things have got to go...
The stinkbugs started coming in my NW D.C. bedroom (the easiest outside access room in the house) at the beginning of fall. I must have seen a couple hundred since then. They love to hide in clothes/suitcases so that anytime I travel, stink bugs inevitably end up at my destination as well. :/ If I forget to check my jacket before I leave the house, there will likely be one in the hood riding along with me. Oddly, I've gotten used to cohabiting with them and transporting them out the window as I find them, but it seems to me now their next adventure will be down the drain, if only for the sake of American produce.
I usually get thousands on my doors and windows so I try and catch them all in a soda bottle. Then I patrol my house shaking the bottle of stinkbugs like a maraca. What I want to know is what thier eggs look like and what they are eating around my house because there are no fruits or vegetables around. There are so many of them that they must be eating a lot of something. I hate them.
@Jan Vones I think that they are cute too... My wife Rachel and I never kill them, we think they are kind of neat. The only time they can be annoying is when we accidentally step on one =/
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