Fauna Kane is a Republican in Southern California. Oddly enough, she is not furious about immigration.

She is not sporting the latest fashion statement, the yellow “No más!” button that Republican legislators wore at the state Capitol on Thursday night to welcome President Vicente Fox of Mexico. She has not been calling radio shows to denounce the traitors in the U.S. Senate who voted to liberalize immigration.

At age 95, Mrs. Kane takes the long view. When she hears members of the House opposing a guest-worker program and vowing to slow the flow of immigrants, she wonders what lawmakers are contemplating for their old age.

“Maybe the congressmen think their pensions are so good they’ll be able to buy whatever they want when they’re old,” she says. “But if we didn’t have foreigners, we wouldn’t have anybody taking care of us.”

Mrs. Kane has a room in Holiday Villa, an assisted-living home in Santa Monica with two dozen nurse’s aides, cooks, housekeepers and other workers born in Mexico, El Salvador, Belize and the Philippines. The only native-born Americans are the director and one assistant.

“I’m the minority here,” says the director, Mary Ann Anderson. “We depend on immigrants — legal immigrants — to provide care, and we’re going to need more and more of them as the baby boomers age.”

This is not the perspective of members of Congress up for re-election. They’ve focused on the immediate costs of immigration for city and state governments in border states like California, which do indeed foot the bill for providing services to low-income immigrants and education for their children.

But immigrants’ children have a habit of growing up to become workers — and workers will be in demand as the baby boomers retire. The boomers haven’t taken the traditional precaution for old age, which is to have lots of children.

The fertility rate of native-born Americans in many states, including California, has fallen to near or below the replacement rate, as it has in European countries that are struggling to support their aging populations. Worried European leaders have been trying to reverse the decline by offering subsidies to parents, like the hefty payments announced this month by President Vladimir Putin of Russia.

But America is in better shape than Europe. Its population is still growing robustly, partly because of the arrival of adult immigrants, and partly because immigrants don’t have to be bribed to have children. Their higher fertility rate helps offset the natives’, bringing the overall national rate just about up to the replacement level.

Some “no más” natives complain that the country can’t absorb immigrants the way it once could. But these natives also expect Social Security and Medicare to sustain them during their retirement. Now that birthrates are low and retirees are living so long, America needs immigrants more than ever.

If there were a moratorium on legal immigration, the Social Security deficit would rise by nearly a third over the next 50 years, according to Stuart Anderson of the National Foundation for American Policy. Even illegal immigrants help the system’s finances, because when they give employers bogus Social Security numbers, the taxes paid on their behalf end up in the trust fund.

With fewer immigrants, we’d have to either raise taxes or cut retiree benefits. And who would do the work they’re now doing?

It’s been argued that they could be replaced by paying higher wages to natives or by automating the jobs. But those higher salaries would be a serious strain on public agencies as well as on retired baby boomers with fixed incomes. And there are a lot of jobs that can’t be done by robots, like caring for the elderly residents at Holiday Villa.

“If it weren’t for the help from the people here, I think I’d be a bag lady,” Mrs. Kane says. “I have people I can call in an emergency, but you can’t count on your friends or family for little things like opening a tube of toothpaste or getting you to the doctor.”

As the population ages, it’s going to get harder to find young people to do those jobs unless the Republicans in the House go along with the Senate’s plan to add legal immigrants. But Mrs. Kane can understand why those Republicans aren’t worried about their golden years.

“They’re not thinking ahead, but nobody does,” she says. “I never thought this would happen to me. You think the good Lord’s going to take care of you.”