This year’s Christmas Grinch might be slugs.

That’s what’s slowing delivery of Christmas trees from Oregon and Washington to local retailers.

The problem was discovered during the first week of November when the first batch of trees arrived from the Pacific Northwest by container ships.

"Some of the trees were infested with slugs," said Carol Okada, manager of the state Department of Agriculture Plant Quarantine Division.

Okada could not give specific figures on the slug infestation because she is on holiday with family in Kansas and didn’t have the information.

Okada said even Pacific Northwest Christmas tree shippers don’t know why there is such a large infestation of the slugs, which are an invasive species that can carry rat lung disease.

There has been speculation that the problem may have occurred because "the weather was very wet" this year and slugs took refuge in the trees, she said.

Officials from Washington and Oregon who were here earlier this month were "shocked" by the slug problem, Okada added.

The Oregon Department of Agriculture reported on its website that last year 16 containers, from five shippers, had live yellow jacket wasps and multiple species of slugs not known in Hawaii. The trees in 10 of these containers were treated at the port of entry and released. The owners of six containers of trees had their trees rejected when they refused post-entry treatment options.

Oregon reported that last year about 230 containers were shipped to Hawaii, which means about 138,000 Oregon Christmas trees were sold in the state in 2011. A similar number is expected this year.

In the 2009 season, Oregon reported there were six shipments of Christmas trees rejected due to pests.

Okada said that once the slug infestation is discovered, each tree has to be individually treated either by shaking it or hosing it with hot water.

That means that state agriculture plant inspectors will have to be at the quarantine plant sites at the Matson and Horizon Lines shipping yards supervising the operations seven days a week.

OKADA said the problem is exacerbated by cuts made by the administration of Gov. Linda Lingle, which slashed the number of plant inspectors to 55 from 95.

Okada said the cost of clearing the trees of slugs will have to be borne by the importers.

But the state will have to absorb the overtime cost for the plant inspectors, who also are needed to clear other items being shipped to Hawaii this holiday season.

"It’s a heavy time for us," Okada added, noting that during the holidays a constant flow of seafood products, plants and other items arrives in the islands.

"We will be stretched to the max," she added.

However, Okada said that there will be Christmas trees for sale because once a shipping container has been been found to be free of slugs, it is released to the importer.

The manager of Costco in Iwilei told the Star-Advertiser on Wednesday that there are trees for sale.

A random check also found that there are Christmas trees for sale at Lowe’s and Home Depot in Iwilei.

Carol Ai May, vice president of City Mill, said Thursday her company has gotten only three of 10 shipping containers it ordered.

"We’re bummed," May said, "because we were planning a Black Friday special selling 4- to 6-foot trees for $19.98."

However, City Mill still plans to continue that special, May added.