A resident in the Sacramento infestation site shot this photo of brown marmorated stink bugs aggregating on a tree. DD and Jim Cathcart/Courtesy photo

By Jeannette Warnert

A well-established population of brown marmorated stink bugs has been found in a Sacramento neighborhood, reported Chuck Ingels, UC Cooperative Extension adviser for Sacramento County — the state’s first reproducing population of the pests outside of Los Angeles.

Ingels said he had no difficulty finding the pests on tree foliage and flying around when he visited the midtown site, centered around 13th Street, south of Capital Park, last week. 

“This is the worst invasive pest we’ve ever had in California, but there is no funding to attempt to eradicate it, nor is there a mandate to do so,” he said.

The stink bugs, which are native to China, Japan and Korea, affect many different crops and are a serious residential problem. They move around easily, so they can be expected to spread.

The bugs can fly up to a half-mile at a time and also travel long distances by hitching rides in vehicles or inside furniture or other articles when they are moved, often during winter months. As a result, most new infestations are found in urban areas.

The stink bugs feed on dozens of California crops, including apples, pears, cherries, peaches, melons, corn, tomatoes, berries and grapes. Feeding on fruit creates pock marks and distortions that make the fruit unmarketable. In grapes, berries collapse and rot increases.

Wine tasters have been able to detect stink bug odor in wines made from grapes that had 10 bugs in a 35-pound lug.

The bug is also a pest of many ornamentals, especially fruit-bearing trees, princess tree, common Catalpa and tree-of-heaven.

In addition to the damage caused by their feeding, the bugs can cause problems for homeowners. When the weather cools down, they migrate in droves to sheltered areas, including inside homes and buildings.

“These bugs aggregate in such numbers that there are reports of people using manure shovels and five-gallon buckets to dispose of them,” Ingels said. “The strong, unpleasant odor the insects emit when disturbed makes cleanup still more daunting.”

Brown marmorated stink bugs were first documented in the in the United States in Pennsylvania in 2001, but was likely established there several years earlier. The pest has spread throughout that state, is believed to be established in at least 15 states and has been found occasionally in more than a dozen additional states.

In 2004, the pest made its way to Oregon and is now established in northwest Oregon and a portion of southern Washington.

The pest has been present in Los Angeles County for six years.

In its homeland, the stink bugs are mostly controlled by parasitic wasps. U.S. Department of Agriculture researchers have collected parasitic wasps in Asia, but they must be tested extensively before they can be released in California — a process that will take until 2016.

“Parasitism is our best hope for reducing populations,” Ingels said. “Chemical control of (the stink bug) is very challenging.”

Ingels said the best way to keep them out of homes is to seal off any potential entry points, especially around window air conditioning units.

Insecticides that have been shown to be effective in the lab are often less effective in the field. In and around the home, insecticides that have efficacy are mostly pyrethroids and neonicotinoids, both of which can have harmful off-site effects.

Pesticides showing efficacy on farms also include organophosphates and carbamates. But growers have worked hard to develop effective integrated pest management programs, and the use of these broad spectrum sprays will set these programs back.

There are also pest resistance concerns with increasing use of these products.

Control for organic growers and home gardeners will be most troublesome, and involves the use of row covers, trap crops, pheromone traps, and predator insects. Ingels is asking growers to be on the lookout for the stink bugs.

“Because they are strong fliers, it’s just a matter of time before they reach farms,” Ingels said.

The pest can be distinguished from ordinary brown stink bugs by its larger size, marble-like coloring on its shield and white markings on the extended edge of the abdomen. BSMB also has distinctive white bands on the antennae and legs.

The best monitoring method is to inspect foliage throughout the year, and larger branches in late summer and fall. A quick method is to beat foliage over a piece of cardboard or sheet.

If the bugs are found, place some in a container and note where and when they were collected. Take the sealed container to the Yolo County Agricultural Commisioner’s office, 70 Cottonwood St. in Woodland.

— University of California Division of Agriculture and Natural Resources News

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A resident in the Sacramento infestation site shot this photo of brown marmorated stink bugs aggregating on a tree. DD and Jim Cathcart/Courtesy photo

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