This holiday season brought some uninvited guests to a few homes where families cut their own Christmas trees -- small colonies of what are commonly called jumping spiders, ferocious-looking but harmless creatures about the size of an aspirin tablet.
And while a household with leaping arachnids is few people's idea of a holiday, entomologists and horticulturalists say that reports of these Yuletide insects is an encouraging sign.
The spiders are a byproduct, they say, of an estimated 70 percent cut in the use of toxic chemicals to control plant-eating insects on Maryland Christmas tree farms since the mid-1980s.
"When you bring a tree home and it's got spiders, that's a good sign," said Dr. Michael Raupp, an entomologist with the University of Maryland at College Park. "When you bring a tree home and its got pesticides, it's not so good."
Still, some folks have been startled by the jumping spiders, which resemble tiny tarantulas and are apt to leap from branch to rug.
"They're not your normal house spiders," said Linda Noell of Rodgers Forge, south of Towson, whose family cut their own tree at a Baltimore County farm. A short time after putting the tree in her living room, she said, she found about 10 small black spiders scampering across her ceiling.
While she insisted she is not afraid of of the insects, she said she isn't particularly fond of them, either. They were dispatched with the help of the family vacuum cleaner, wielded by her husband, Thomas, a salesman.
At Pine Valley Farm near Sykesville, where pesticide use has been cut to a bare minimum, Mrs. Roger Wolfe said two customers have called about spiders in their trees in the past two years. The farm replaced the trees.
"I know how people feel, because I certainly wouldn't want little spiders running around my house, either," she said. So few trees have been affected on the 100-acre farm, she said, "we haven't been too concerned about it."
Chuck Cornell, an entomologist and consultant to several Christmas tree growers who has vigorously promoted reduced pesticide use, conceded that the spiders are becoming "a problem that I didn't foresee."
"It's an uncomfortable situation for me," he said. "People don't like bugs in the house. My work is so successful, but I fear it may somehow become detrimental to the sale of the trees."
The low-pesticide growing method advocated by plant and insect specialists is called integrated pest management.
"What your grower is doing is getting away from a treatment called a 'cover spray,' where he blasts the whole plantation with a chemical," Dr. Raupp explained.
Instead, the grower will use a less lethal chemical to kill harmful pests on one or a few selected trees. The rest of the trees then create "a refuge of untreated places where beneficial organisms can live" and eat the harmful ones, Dr. Raupp said.
"Really, these spiders aren't doing any harm," said Dr. Francis R. Gouin, a horticulturalist at College Park. "They're very beneficial, as a matter of fact. If people are leery of them, they're probably too leery of too many things."
The best way to handle the spiders, he said, is to brush them onto your hand and carry them outside, where they can hibernate for the winter and wake up to a feast of less friendly insects.
"A hopping spider, the minute it feels the warmth of your hand, it will slow right down," he said.