leaf miners & veggie quality

Does anyone know if leaf miners (not a HUGE infestation) affects the quality (beets) of the vegetable?

One or two will not noticably affect the quality of beetroot, but larger infestations will reduce the size and quality (since they're eating the photosynthesizing material in the leaf). If you use the beet greens, they will have an effect.

It seems like the leaf miners have a cycle here, I don't have them all season. I use beets as an indicator to let me know when to plant spinach. If the new growth looks good, it is time to put in the fall spinach.