University City

October 18, 2013

Bugs raise a stink in homes, gardens

What’s single-minded, stinky and likes to hang out in the house?

What’s single-minded, stinky and likes to hang out in the house?

No, this isn’t a Jon Stewart joke about Washington, D.C.

The correct answer is the brown marmorated stink bug, an invasive pest that’s creating big problems in North Carolina and dozens of other states.

With cold weather just around the corner, swarms of these brown bugs have been invading houses for warmth. They don’t bite or cause structural damage, but they can be a major nuisance for residents.

In farms and gardens, however, they’ve done enormous harm, and they will probably be back to cause even more problems next year.

According to Jim Walgenbach, an entomologist with N.C. State University who has been intensively monitoring the bug populations this year in North Carolina, researchers think they have “pretty good handle” on the bug’s distribution and numbers.

In 2013, Walgenbach said, “we observed a significant increase in numbers in many areas of the Piedmont and mountains of North Carolina. Based on our field surveys and reports from extension agents and homeowners, the largest populations extend from about Greensboro to Asheville.”

For some reason, he added, the Coastal Plain has not been heavily affected.

In infested areas, large numbers massed together and entered homes from mid-September through early October, Walgenbach reported. The good news is that the activity seems to be rapidly subsiding in recent days.

Brown marmorated stink bugs look similar to native brown stink bugs. You can tell them apart in various ways; one is to look at their undersides. The native bug’s belly is pale and greenish; the BMSB’s is brown. BMSBs also have light-colored stripes on their antennae.

Like its native cousins, the BMSB emits a very unpleasant smell when squished, earning it its common name.

Both damage crops by stabbing them with their sharp mouthparts and sucking out the sap, in the process sometimes injecting diseases as well.

That said, native stink bugs are bad enough, but BMSBs are much worse. Voracious feeders, BMSBs have done millions of dollars of damage, particularly in Middle Atlantic and Southeastern states, destroying fields of sweet corn, tomatoes, peppers, peaches, apples and other crops since first showing up in Pennsylvania in the 1990s.

Thought to be of Korean origin, they left their natural predators behind and have exploded in numbers. Current pesticides are not very effective at controlling the bugs. The pesticides also damage the native insects and diseases that are key to addressing the problem sustainably.

A task force funded by the U.S. Department of Agriculture, and that includes Walgenbach, is now hard at work looking for solutions.

It gets worse. Like another recent invasive species from Asia, the kudzu bug, BMSBs also swarm into structures, including homes, at the onset of cold weather, then snooze through the winter to emerge in the spring and renew their attacks.

When one BMSB finds a house it likes, it gives off a pheromone (humans can’t detect it – it’s unrelated to the insect’s “stink” defense) that attracts hordes more BMSBs.

Since pesticides are ineffective, scientists recommend that residents take special care to block all cracks and spaces where bugs might enter, and to pay special attention to windows, doors and, most of all, window air conditioning units, which seen to be especially attractive entry points.

In heavily affected areas, people are being told to minimize outdoor lighting and to keep windows and doors closed, even in nice weather.

It appears the worst may be past for the University City area. David Goforth, horticulture agent with the N.C. Cooperative Extension Service in Cabarrus County, believes he has seen some BMSBs in the area, but he said, “we haven’t had any problems like they have further north.”

All the same, BMSB stink bugs are worth watching out for next year, especially for organic gardeners and farmers, who find control even more challenging.

Organic Gardening Magazine’s website, in a special page dedicated to the BMSB, suggests making sure to plant sunflowers, French marigolds and other insectary plants to create habitat for organisms that eat BMSB eggs and attack their nymphs – ladybugs, lacewings, tiny predatory wasps, ants and other beneficials.

Long term, the future is more hopeful. In Asia, though they remain a minor nuisance and pest, BMSBs are largely kept in check by their natural enemies. It is only a matter of time before nature rebalances things here.

In the meantime, urban edible pioneers might be in for some pretty stinky situations.

Garden note

The call is out to remind people to band trees against cankerworms, a great idea that’s environmentally friendly and highly effective.

David Goforth recommends putting up the tar paper or gorilla tape bands now, but not adding the sticky Tanglefoot – needed to catch the pests as they climb the trees this fall – until “cold weather.”

Based on experience, Goforth defines this as the first night to drop below 26 degrees F.

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