NEW ORLEANS  They are the men still rebuilding New Orleans more than three years after Hurricane Katrina, the head-down laborers from Honduras, Mexico and Guatemala who work on the blazing hot roofs and inside the fetid homes for a wad of cash at the end of the day.

But on the street, these laborers are known as “walking A.T.M.’s.”

Their pockets stuffed with bills, the laborers are vulnerable because of language problems and their status as illegal immigrants. And as Hispanics have become the prey of choice in crumbling neighborhoods here in one of America’s most crime-ridden cities, racial friction between the newcomers and longtime black residents has moved close to the surface.

Geovanny Billado, a worker from Honduras, spoke of one incident in which “they waited to punch me,” and “one of them stabs me with a knife.” It was four against one, Mr. Billado said, and he lost the $350 he had earned; another time, it was seven against one.

“You don’t get a chance to say anything,” he said. “They just fall on top of you. It’s better to just give the money up front. If you don’t give it to them, they’ll beat you and take it anyway.”