Flanked by potato and sugar beet fields, the desolate stretches of Interstate 80 may seem an unlikely setting for an angry confrontation. But for a growing number of U-Haul-towing California migrants, Idaho is downright hostile territory.

On and off the road Idaho's proud natives have their own language for the newcomers who cross the western state line in overloaded swaying station wagons and motor home. Oldtimers call them goats; the new generation calls them C.B.s (literal translation, "California Bastards").

"Let's just say I was glad to get rid of my California license plates," says Bob Trerise, personnel manager for a Boise computer firm. Three years ago, Trerise, his wife and two children moved here to Idaho's capital and largest city from Palo Alto, Calif. Their reception was less than lukewarm. "People would say, 'Oh, you're from California,' and it wasn't until I told them I was born and raised in Montana that they would warm up to me," Trerise remembers.

En route to their new home in suburban Boise, Earl and Nancy Dunn, new arrivals from Los Angeles, also received the cold shoulder after coming bumper to bumper with one of Idaho's most popular tail-end stickers -- "Don't Californicate Idaho."

"My God, what have we done," Mrs. Dunn asked her husband. "Why do they hate us?" Earl Dunn's answer was immediate and to the point: "Because there are so many of us."

Exactly how many Californians nobody knows for sure. Idaho's Bureau of Vital Statistics estimates only net migration figures and does not categorize new immigrants by states. But check with California's Department of Finance shows that 9,500 transplanted Californians traded in their old license plates for Idaho tags last year, an increase of 2,600 over 1977. Most of the newcomers were white and from the San Jose and Los Angeles areas.

Indeed past population studies indicate that California supplies Idaho with more newcomers than any other state. Thirty-four percent of the people moving to Idaho hail from California.

A good share of the California tide is attributed to word-of-mouth reports that Idaho, a state with vast stretches of untouched wildernesses, abundant resources and few people (950,000), is the new "promised land," a place far away from rising crime, the smog and asphalt jungles of Orange County.

One Boise resident who lives on a tree-shaded street in the city's oldest residential area expresses his amazement that his new neighbor was a friend of several other Californians who moved to Boise years earlier. "My neighbor across the street . . . he was the fourth in the circle to arrive. Right now I can look out my window and see the homes of five transplanted Californians. It's incredible."

For the natives the migration of Californians conjures a fear that Idaho will be turned into a mass of freeways, parking lots, hamburger stands, nudist colonies, high-rise developments, tract houses and neon billboards.

Simple economics may say more about the anti-California sentiments. In a 1974 study, Lamar Bollinger, an economics professor at the College of Idaho (a school with a student body 18 percent Californian), reported that three times as many of Idaho's West Coast immigrants were college graduates as were native Idahoans. "The new residents compete for our jobs and if they are better educated, they may be able to compete on more favorable terms," he concedes today.

In Boise, where the "California problem" is openly discussed at the seediest bars and the mose uptown cocktail parties, the new immigrants are often blamed for the inflation in housing prices. "I've been in real estate for five years," says Joan Matlock, a Boise agent, "and I've seen what they've done here . . . they make a bundle on their tract homes in California and then they come up here with $30,000, $40,000, $50,000 equity in their pockets and they're willing to pay almost any price. It doesn't matter because they have the money to cash anybody out. It's unreal."

"Of course we're responsible for some of these rising real estate prices," says Chuck Kuhlman, a 35-year-old former Los Angeles businessman who moved to Boise with his wife and nine-year-old son a year and a half ago. "But nothing is ever mentioned about the adjoining neighbors who seem to benefit from this . . . Or the new jobs we create."

The former owner of a pharmaceuticals distributorship and an accounting firm, Kuhlman was able to sell his $300,000 Encino, Calif., house and build a 5,000-square-foot rambler in Boise for half the price. He invested the rest of his savings in a $500,000 computer-operated car wash on a busy corner lot, once the site of a gutted gasoline station.

"At first I was just another Californian spending money -- one of those weirdos," Kuhlman says. "Now I've adapted and people are beginning to understand I live and work in Boise just like anybody else does. And I'm contributing. It takes a certain amount of time."

In Salmon, a conservative ranching and logging community, long-time locals carry on a love-hate relationship with the California immigrants who have settled there to retire and enjoy a slower pace.

Mayor William Cannon complains that the new arrivals want "the pioneer experience with hot and cold running water" and have caused a strain on city services. But Bob Johnson, editor of the town's weekly newspaper, the Recorder Herald, says kicking out the Californians would be like "taking out another sawmill." Salmon, one of Idaho's most economically depressed towns, depends on the Californians for revenues, he says.

Many ex-Californians turned confirmed Idahoans are getting tired of the criticism. "It's the Californians who join the battles to keep the air here clean, the free-flowing waters free flowing, the wildfire protected," insists former Californian Melissa Dodworth of Boise. "We are the Sierra Clubbers, Trout Unlimiteders, Duck Unlimiteders, Idaho Wildlife Federationers."

Recalling his cool greeting from Idaho natives after moving here from Sacramento several years ago, Mike Bunnel, the owner of a Boise record store, talks of a barroom brawl he had with a drunken cowboy who told him to go back where he came from. "The funny thing," Bunnel says, "was that the same guy who told me to go back home was originally from California himself."

But Carolyn Stump, a resident of Barboursville, W. Va., sees nothing funny about the antagonism the Californians sometimes feel. In a letter to the editor of the Idaho Statesman last month, she lashed back at three Idaho youths who she says roughed up her 60-year-old father from California while on a hunting trip. "Although vengeance is not mine," Stump wrote, "I cannot help but hope that the same crow that plucks the seed from your garden also dumps his riches on your head."