HAMDEN -- State entomologists, already on edge over a pair of beetles that threaten Connecticut's forests, are bracing for another invasive threat from the brown marmorated stink bug.

A native of Asia, the small, flat insect has experts worried because its menu reads like a vegetarian's shopping list: corn, peaches, apples, grapes, oranges, tomatoes and even figs. It also devours the soybean plant, a critically important cattle feed crop.

"What's really worrisome is that the brown marmorated stink bug eats 70 different plants in the United States," said entomologist Chris T. Maier, who spoke to a gathering Wednesday at the Connecticut Agricultural Experiment Station's 101st annual Plant Science Day at the station's hilltop Lockwood Farm in Hamden. "It eats almost all fruits, nuts, legumes, even corn."

The brown marmorated stink bug, or BMSB, is believed to reside in all of the lower 48 states. Its first appearance in the U.S. was in Allentown, Pa., in 1996. In December 2008 it was discovered in West Haven.

"The number of counties reporting the stink bug started going up explosively in 2010," Maier said. "It's an excellent hitchhiker. In the fall, millions are flying about, and they find their way into every box truck that's open, every RV with an open door, every mail container, so they're easily transported from one state to the next."

He said that while they're best adapted to tropical conditions, they like to spend the winter in homes and other heated buildings.

"They're also highly mobile," he said, "and they move from one crop field to another from one day to the next, so even it you did spray with insecticide, it would probably be ineffective."

From coast to coast, entomologists are frantically looking for ways to get BMSB numbers down to "acceptable levels." Insecticides aren't viewed as a good solution because of their effect on bees and other pollinators, Maier said. Most insecticides have been found to be useless against it. An Asian wasp that attacks stink bug eggs is being studied by the U.S. Department of Agriculture.

More Information

Bugging out Name: Brown marmorated stink bug. Scientific name: Halyomorpha halys. Invasive range: Likely in all of the lower 48 states. Native range: China, Japan, Korea and Taiwan. Size: Adults are about three-quarters of an inch. Color: Brown with marbled appearance and tiny red eyes. Shape: Flat, shield-like, almost as wide as it is long. Diet: Apples, pears, peaches, tomatoes, berries, figs, mulberries, citrus fruits, corn, persimmons, ornamental plants, grapes, peppers, soybeans and beans. Reproduction: Female lays clutch of 25 to 30 eggs on the underside of leaves. Usually, one generation per year in northern states, multiple generations in the South. Emerging nymphs easily confused with tics. Control: No effective control strategies are known at this time, but research is continuing.

Another possible control technique, he said, might be to plant a worthless crop that the BMSB is highly attracted to, then spray that field. "But the chemicals that look promising are also harmful to bees," he said.

In the Mid-Atlantic, the insect has caused about $37 million in damage to the apple crop alone this year; about 18 percent of the crop was ruined.

The BMSB eats by inserting its protruding mouth into the plant, injecting digestive juices, and sucking up the resulting "plant slurry." It eats different parts of the plant, including leaves, flower buds, stalk, seeds and fruits. When they eat, say, apples in this fashion, the fruit is covered with brown spots where the fruit tissue was "digested." While the apple is still safe to eat, it can't be taken to market.

"In the Midwest, soybean growers are shaking in their boots," he said. About the only good thing about them, experts say, is that they don't bite humans, pets or livestock.

Unlike the "ladybug," which is actually a beetle, the BMSB is what entomologists call a "true bug," meaning it comes equipped with a piercing snout or proboscis, two pairs of wings and antenna that usually has five segments. Others in the bug or hemiptera order include cicadas, aphids, planthoppers and leafhoppers.

There are about 55 native species of stink bugs in Connecticut, 16 of which are beneficial. Most of the others feast on plants, although they specialize on one plant species. The BMSB, on the other hand, seems to like most of the plants that are of high economic importance.

Experts recommend that if you see one in your home, you shouldn't squish it because of the stench that will result. The University of Illinois Extension Service website recommends using a vacuum.

If you find a brown marmorated stink bug, note the date and location, and contact Chris Maier at Chris.Maier@ct.gov. Or send it to Maier at the Connecticut Agricultural Experiment Station, P.O. Box 1106, New Haven, CT 06504.