PHILADELPHIA (AP) _ A species of snail that is considered one of the worst agricultural pests in California has been discovered in Pennsylvania, posing a potentially expensive threat to the state's farms and nurseries.

``The last thing Pennsylvania wants is this snail rampaging across the countryside,'' said David Robinson, a snail specialist for the U.S. Department of Agriculture. ``It's a major pest. It's one of the worst snail problems there is. It feeds on practically anything green and growing.''

The brown garden snails were discovered last month in the garden of a Philadelphia schoolteacher, who told officials that they had been in her garden for 10 years.

Before that, the snail has not been known to survive the winter in Pennsylvania, though state officials fear it may be adapting.

California spends about $7 million a year to battle the snail, which was brought to that state in the 1850s from the Mediterranean, as a delicacy for restaurants.

One threat to Pennsylvania agriculture is the direct damage to plants, but other states also might refuse to import Pennsylvania products because of a snail infestation in the state.

State officials plan a survey of state parks and commercial greenhouse operations to determine whether the snails have spread beyond the Philadelphia neighborhood where they were discovered.

State Department of Agriculture scientists said the snails probably arrived in Philadelphia on garden plants imported from California.