An immigrant beetle with a taste for Scotch pines has taken the joy out of the holidays for many Christmas tree growers and eventually may threaten all of North America's pine forests.

Christmas tree buyers aren't expected to see higher prices or tree shortages this year, according to industry spokesmen.

But the U.S. Agriculture Department estimates that the pine shoot beetle will cost American businesses and taxpayers nearly $900 million in damage to tree crops, landscape trees and standing timber over the next 30 years.

"No question, it will do very, very well in North America," said Robert Haack, an entomologist with the U.S. Forest Service. "We could build up some large numbers quite rapidly. The beetle has the potential to do a lot of damage here."

The Christmas tree business could greatly speed the process. The seasonal movement of more than 35 million freshly cut trees could spread the pest all over the North American continent. Stumps left after the harvest provide ideal breeding spots.

That's the reasoning behind the quarantines established last year in the United States and Canada that prohibit shipment of infected trees outside the county where they are grown.

Quarantines of farms have been extended to twice as many counties as last year in the two countries, but foresters say this will only slow, not stop, the beetle's inevitable spread to natural woodlands.

Six states--New York, Pennsylvania, Ohio, Indiana, Illinois and Michigan--and Canada's Ontario province have quarantines this year.

Standards are strict. Agricultural inspectors in both countries check each Christmas tree grove in November, just before harvest. Every tree is inspected for any sign of the beetle. All trees from an infected grove are restricted.

"One beetle can literally shut you down," said Gary Reissen, owner of a 1,700-acre Christmas tree farm in Greenville, Mich.

The shiny, dark, cylindrical insect, no larger than a match head, is a recent invader from Europe and Asia. It has swept through Christmas tree farms around the Great Lakes region since it was discovered last year in Ohio.

Preliminary studies show that it will thrive on any of North America's 35 pine species, although it prefers the Scotch pine--the favorite Christmas tree--which is plentiful on tree farms and in forests.