Defusing a Stink Bomb

How one very foul-smelling bug could ruin your garden this year.

by Brendan Skwire

Alyssa Grenning

I've lived in the Kingsessing neighborhood of Southwest Philly for more than a decade. Over the past four years, I've been steadily building my backyard garden, beginning with a few in-ground plots and progressing to the series of raised beds I have now. Every year I learn more, especially when I make a mistake. I mean, who coulda predicted that without a trellis, my spaghetti squash would take over most of the yard, climbing all over the deck and completely enveloping the fence that separates my neighbor's yard from mine?

Most of my amateur errors didn't have serious ramifications — my neighbor enjoyed all the squash that grew on her side of the fence. But last year I learned a big lesson about the brown marmorated stink bug, a nasty little pest that invaded Pennsylvania just over a decade ago, and whose numbers have been growing (and eating) exponentially ever since. They hit Philly in force in 2009 and ate about a third of my crops. It took me six months of searching on the Internet and calling the agriculture extensions of local universities to determine what the bug even was. What I learned wasn't pretty: This pest is ravenous. What's worse, there are no specific natural or chemical pesticides that will do it in, and you can't rely on natural predators to control them, either.

Like most bugs, the brown marmorated (that's entomologist speak for "marbled") stink bug, or BMSB, goes through a number of stages before it becomes an adult. These immature stages are called instars, and in its first, the little bastard looks an awful lot like a ladybug. Which explains why I was caught completely off guard by the holocaust that hit my veggies. I'd happily let the red-and-black baby bugs clustering on my broccoli and Brussels sprouts alone, figuring they were warding off beetles and aphids. The truth was much more insidious: Those little invaders were sucking the crops dry, leaving a swath of destruction in their wake that would make William Tecumseh Sherman blush. When they turned on my cabbages, it was too late: I had an infestation.

I found a photo of the bug on the Internet and posted it on my Facebook. The response was immediate: "I HAVE THOSE!" a friend in Fishtown wrote. "THEY KILL EVERYTHING, WHAT CAN I DO?"

The unfortunate answer: not much. I got in touch with George Hamilton from the Department of Entomology at Rutgers University's Agriculture Extension, which has done a lot of research on the stink bug (fun fact: They get their name because when you smoosh 'em, they stink like rotten cheese or burning rubber). According to Hamilton, the BMSBs first appeared in Allentown in 1996, one of many unintended consequences of globalization. They hitched a ride from China and began reproducing in local farms almost immediately. They lay their eggs from June through September on a weekly basis, and the babies hatch just a few days later.

"Depending on where you are, their populations have slowly built to large levels," says Hamilton. "They're a huge problem in New Jersey, Pennsylvania, parts of Delaware and Maryland and even West Virginia. They'll feed on tomatoes, peppers, peaches, pears, apples, depending on time of year. Stink bugs also eat butterfly bush and asparagus."

HALF OFF DEPOT

Why live life at full price?

Perhaps the main reason the bugs are difficult to get rid of is that they left their natural predators back in Asia. And while there are some critters native to the United States that eat the brown marmorated stinker — including predatory stink bugs, assassin bugs and two types of egg parasites — most of them eat a wide variety of insects, so they're not all that useful as a control.

Where the BMSB is concerned, there's no defense like a good offense. Rutgers lists several insecticides that may be effective against Mr. Stinky, but Hamilton warns, "You have to be cautious about the crops you want to treat." Rutgers provides a pared down list of products, but advises you read the labels. Furthermore, many are meant for indoor use. When I ask about pyrethrins, natural insecticides produced by certain species of chrysanthemum, Hamilton tells me that the research hasn't been completed. "You could plant daisies, which produce pyrethrum, but the bugs would have to feed on it," he says, and he just doesn't know if they do. "We haven't tested natural pyrethrum, but the pesticides we list are based on that substance, so it would make sense that natural pyrethrum might have an effect on them." Hormone traps, like those used to control Japanese beetles, don't exist for the stink bugs yet. "One specific problem is the stink bug isn't attracted to those traps as instars, but only as adults.

"You might try spraying your crops with neem oil," suggests Hamilton of the concentrated oil from a species of evergreen native to India that is known to kill a number of pests by preventing them from feeding and breeding. Hamilton adds that your best bet is probably hitting your crops with a stiff spray from the hose to knock off the bugs. I've used this method, and find it works fairly well, albeit temporarily (the bugs, they always come back). I've also experimented with making my own natural pesticide from Dawn dish-washing detergent, a little white vinegar and water, rejoicing as the bugs rolled over and died within a few seconds of spraying them. You can find a number of recipes online, but if you make it too strong, you'll kill your plants worse than the stink bugs will.

I wish I could tell you there was some kind of panacea to help rid your raised beds of brown stink bugs. But the most you can do is keep your eyes open for signs of an invasion, and act quickly to limit the damage. Learn what the egg clusters look like, and remove them if you can. Kill the bugs on sight. Get row covers. WHYY's Mike McGrath  has a list of strategies, and I highly recommend his archives at gardensalive.com. Like so many invasive agricultural pests, the brown marmorated stink bug isn't going anywhere soon. If last year is any hint of what's to come this summer, arm yourself. Now.

Brendan Skwire blogs at brendancalling.com.