Invasive bugs making a bigger stink

Newark, Del. — The brown marmorated stink bugs that took a $37 million bite out of the Mid-Atlantic’s apple crop last year have awakened from winter hibernation, mated and morphed into a possibly larger threat to farmers and homeowners.

These stink bugs are the offspring of the same plague that freaked out Maryland, West Virginia and Pennsylvania homeowners last fall when they crawled into houses to hibernate after the feast, seeking warmth in cracks, and, in some cases, near sleeping humans.

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That kudzu seemed like a good idea at the time . . .

They started creeping out of hibernation and coupling in late May. Their eggs hatched within three weeks, and their babies, or nymphs, reached adulthood within six weeks. They will possibly return to homes and other warm places when temperatures dip in late September.

Government entomologists say this year’s plague seems worse in many areas, and they expressed a particular worry about this invasive species from Asia, which has no natural predators in the United States. The warmth-loving insects appear to be migrating from eastern Pennsylvania, where they were first spotted in 1998, to the sunny Southeast, where the population might explode.

“If they get to Florida, it could be like the atomic bomb going off,” said Douglas G. Luster, research leader for the U.S. Department of Agriculture’s Agricultural Research Service. “They’re starting to show up in North Carolina.”

In a desperate search for a solution, the Environmental Protection Agency recently approved limited use of two insecticides to help control the pest, and researchers at a government lab in Delaware are conducting studies to determine whether a non-stinging parasitic wasp that preys on brown marmorated stink bug eggs in China, Japan and South Korea can be introduced here.

The Asian wasp isn’t much bigger than a period that ends a sentence, but introducing the insect is risky because it, too, could become invasive and attack native insects that are beneficial to the Mid-Atlantic’s ecosystem. If the wasp became a threat, it would join a host of species from Asia on the government’s most unwanted list of harmful plants, insects and animals.

But the risk might be worth it, entomologists said. Detected in 33 states and the District, the brown marmorated stink bug munches on hundreds of varieties of plants and trees. It has a taste for fructose, stabbing its mouth — or proboscis — into apples, peaches, grapes and other fruit at the start of harvest season. Last year, it ruined nearly half of Pennsylvania’s peach crop, worth $15 million, said experts at the Penn State Cooperative Extension.

“The growers who have the most fear are the fruit growers,” said Jerry Bruste, secretary and treasurer for the Maryland Vegetable Growers Association. “It will devastate them.”

In a secured section of the Beneficial Insect Introduction Research Unit at the University of Delaware in Newark, researcher Kathleen Tatman described last week how the Asian wasp kills the stink bug.

As stink bugs lounge on paulownia leaves and suck on vegetables and fruit, the wasps target stink bugs’ tiny clusters of perfectly round, milk-colored eggs and use them as hosts for larvae that eat them from the inside. Asian stink bug eggs are thought to be the perfect size for the wasp, its mortal enemy.