White specks on framing lumber
That's insect damage from when the tree was still in the forest. It's not really a problem now since the board has been cooked in a kiln. Any insects have leave the vicinity or been destroyed by heat. A few such boards are common with any unit of lumber, but if you see more than maybe 5% like that I'd be questioning whether your builder is buying from a reputable source.
That said, boards like that tend to be very soft and shouldn't be used in critical locations. They include wood that was probably dead at the time of harvest and is partially decomposed. For a common stud, not a concern. For a header or other specialty bit, it's to be avoided.