OK, that's pretty good evidence.
They aren't mealy bugs, are they? They don't look like it from the
photo. Mealy bugs would move around. The ones on the wall would have to
move to go find a plant to feed on.
From your pictures they look attached to the wall and they look oval in
shape. Right? If you squash one, is there liquid inside like a living
thing? Can we rule out it being some sort of fungus growth?
Your original idea of egg cases may be right. I'm just trying to rule
out other things because if they ARE egg cases, I still don't have any
idea what they are. Also, egg cases shouldn't harm a plant (though the
insect that left the egg cases might have).

Steve

rachael traub wrote:
they are growing on the mint too. leaves in the area of the eggs are dying back.

Steve wrote in message ...

I can't recognize them from that photo. (Not sure I could with a better
photo either.)
What evidence do you have that the white things on the wall have
anything to do with the decline of your mint?