A new stinkbug swarming in Sacramento’s downtown gardens

Published: Friday, Sep. 20, 2013 - 12:00 am
Last Modified: Saturday, Sep. 28, 2013 - 12:16 am

The school year was just starting when Sacramento resident Vilaiporn Zalunardo first noticed the arched, shieldlike insect crawling across her bedroom window screen.

Upon closer inspection, she saw another, and later a few more hovering nearby.

Concerned they may be an unusual species of cockroach, Zalunardo took to the Internet. There, she became acquainted with the brown marmorated stinkbug: a leggy, flying insect that appears to be wearing a small plate of armor on its back. Scientists deem the marmorated stinkbug one of the newest “superpests,” and it now calls a patch of downtown Sacramento home.

“I’ve been living in this house for 11 years and this is the first time I’ve seen them,” said Zalunardo, pointing to several on the eaves of her house near 13th and P streets. “They have tried to get into the house whenever I open the front door. Now, I’m scared. I don’t like this.”

Indeed, plenty of the stinkbugs were flying around the city’s downtown just south of Capital Park on Thursday, most noticeably on 13th between P and T streets. This is the area where entomologists have documented an infestation that covers over half a square mile. It is believed to be the first reproducing population in California outside of Los Angeles County.

The bugs have been spotted in other parts of Sacramento, as well. Gardeners complain the bugs have been feasting on Chinese cabbage and other Asian greens at the community garden in Bill Bean Jr. Memorial Park in south Sacramento.

It’s because of their taste for greens – and many other plants – that brown marmorated stinkbugs become a problem. They typically start out in urban gardens, then spread to agricultural areas, where they’ve been known to damage tomatoes, corn, berries, grapes and array of other fruit crops.

The insect is native to China, Korea and Japan. It often is confused with the similarly colored consperse stinkbug, which already is established in California and considered a pest for squash and pear trees. The bug gets its name because of the pungent odor it emits when squashed.

In the United States, the presence of the brown marmorated stinkbug first was documented in Allentown, Pa., in 2001, after a homeowner collected the insect and had samples sent to Cornell University for identification, said Tracy Leskey, an entomologist with the U.S. Department of Agriculture’s agriculture research service. Since then the stinkbug has set up shop in 41 states.

The bug is not considered a threat to humans. Rather, it is seen as a nuisance as it gathers, often by the hundreds, on the outsides and insides of homes. Stinkbugs become more apparent in autumn, when they can be seen flitting around homes, mostly in urban areas.

“They over-winter in cool, dry locations, and oftentimes this just happens to be people’s homes,” Leskey said.

Problems with the stinkbug really began a few years ago, with their move into agriculture, Leskey said. In the mid-Atlantic states, where the pest has made the deepest incursions, the stinkbug caused an estimated $37 million in damage to orchards in 2010, she said.

The stinkbug casts a wide net for sustenance; entomologists have established it feeds on more than 100 plant species. “It will feed on everything from a box elder tree to a pepper plant,” Leskey said.

In some cases the stinkbug has come into vineyards, she said, feeding on the grapes until they collapse. Leskey said it’s not yet clear how dire a threat they pose to viticulture. But their presence at harvest time can be a concern: “There is a problem with contamination of wine,” she said.

The insect spreads by hitchhiking on vehicles and planes. Entomologists estimate it has been in California since 2007, and arrived in the Sacramento region around 2009. “There is a period when it begins to establish itself – and then the population begins to build,” Leskey said.

Controlling the stinkbug poses a dilemma for scientists and farmers given one of its main enemies is the parasitic wasp, said Chuck Ingels, farm and horticultural adviser with the University of California Cooperative Extension in Sacramento County.

The parasitic wasp is not found in the United States, and its introduction has not been approved by the USDA or the California Department of Food and Agriculture. Both agencies want to make sure the wasp will affect only the stinkbug species before approval.

In the meantime, the stinkbugs will continue to populate – and feed. Ingels said it may take one to three years before they become a problem on area farms. Without pesticide controls, he said, “they could spread fairly quickly.”

Call The Bee’s Edward Ortiz, (916) 321-1071. Follow him on Twitter @edwardortiz

Read more articles by Edward Ortiz

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