Vanessa, an illegal immigrant, has harvested fruit in Kerman, Huron and Madera for four years. Until this summer, she had never seen a white face in the fields.

Then one day, four teenagers showed up at a cherry orchard. They didn't speak Spanish, and they didn't seem to know what they were doing.

"Everybody was surprised to see them there," Vanessa said.

It didn't go so well for the newcomers. Within an hour, all four had quit.

At the heart of the debate over illegal immigration is a question that burns as hot as the afternoon sun hovering over the Central Valley: Are illegal immigrants doing the work that no one else wants, or are they stealing jobs from Americans and dragging down their wages?

To some extent, both are true.

As Vanessa's story shows, some jobs might go unfilled — even in tough times — without illegal immigrants.

But there are drawbacks. Illegal immigrants push down wages for legal workers in food-processing, factory and service jobs, economists say. Because illegal immigrants will work for almost any wage, employers have little reason to pay other workers more. Sometimes jobs that low-skilled Americans would be willing to do, such as washing dishes and cleaning bathrooms, are instead taken by illegal immigrants.

Illegal immigrants help the nation's private-sector economy by providing cheap labor — something that is especially critical for the Central Valley. But their competition with low-skilled American workers and their strain on local government budgets cancel out that boost for that nation's overall economy, some economists say.

In the end, illegal immigration in the Valley means businesses are big winners while many blue-collar workers lose out.

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