Mighty invasion plagues beehives.

Byline: Tim Christie The Register-Guard

The varroa mite is a tiny, eight-legged blood-sucking parasite that is making life miserable for beekeepers and farmers who depend on bees to pollinate their crops.

The reddish-brown, saucer-shaped arachnids, each about the size of a grain of rice, feed on the blood of honeybees, causing weight loss, deformities, disease and reduced lifespan. They can destroy an entire colony within a few months.

The parasites, which have grown resistant to approved miticides, have wiped out thousands of hives in Oregon and across the country this winter, leaving beekeepers scrambling for a new way to eradicate the pest. The bee shortage has left farmers, notably California almond growers, paying top dollar for healthy hives to pollinate their crops.

"The mites are going to wipe us out unless we get someone to figure out what to do to kill the mites," said Laura Ames, whose family raises bees in Elmira.

The Ameses lost at least one-third of their hives this year, leaving them with about 400 colonies, which are now in California, parked in almond groves, she said.

Beekeepers don't know how many hives have been lost all told, but estimates range from one-quarter to two-thirds of the colonies in the West and the upper Midwest, said Kenny Williams, president of the Oregon State Beekeepers Association.

California has more than 500,000 acres of almonds, requiring about 1.1 million hives to pollinate the trees from mid-February to mid-March. Each colony is home to about 40,000 bees. About half of those bees come from out of state, and this year there are just not enough bees to go around, Williams said.

"That has created intense demand for beehives on the part of almond growers," he said.

Last year, almond growers paid about $54 per hive for a pollination fee. This year, they're paying $80 to $100, Williams said.

Oregon is home to only about 20 commercial beekeepers, who generate about $4.5 million a year in honey production and hive rentals, Williams said. But their economic worth goes beyond that: The Oregon crops they pollinate are valued at $280 million, he said. In addition to the commercial beekeepers, there are hundreds of hobbyists and "sideliners" - farmers who raise bees on the side.

The varroa mite first emerged as a threat to honeybees about 10 or 12 years ago. They infest the breathing tubes of bees, and causes hives to become smaller, said Susan Hansen, a beekeeper in rural Clackamas County.

Beekeepers had an effective treatment, in the form of a plastic strip coated with one of two miticides that is placed in hives when the bees are dormant. But over time the mites became resistant to both approved miticides.

California beekeepers began noticing problems last summer, Hansen said, and the problem soon spread.

Scientists are working on several possible solutions, Williams said. One is formic acid, a hazardous material that so far has proved difficult to apply safely. They are looking at Oxalic acid, which is found in lettuce and is more benign, he said.

Federal researchers are looking at a potent fungus, Metarhizium anisopliae, that kills varroa mites but doesn't harm bees or their queen, according to the U.S. Agriculture Research Services.

In field trials, researchers placed a fungus-coated strip inside a hive. All the bees in a hive were exposed to the fungus within 10 minutes, and most of the mites on them died within three to five days. Researchers say the fungus doesn't kill as quickly as miticide but is just as effective, and beekeepers won't have to worry about mites becoming resistant to the fungus.

Researchers also are trying to breed mite-resistant bees, using bees that previously lived in hives that have survived the mites, Williams said.

The survivor bees either comb the mites off their body or crunch them in their mandibles, injuring the mite enough so that it doesn't bother any more bees.

Williams, who raises bees in Blodgett, west of Corvallis, said the mites didn't hit his hives too hard this winter, though he's not sure why. But the bees that survived don't look as strong as they could, he said.

"You could say we dodged a bullet," he said, "but I wish I knew what I did right."