Garden Pests and Diseases: Alder pest, 1 by wannadanc

wannadanc wrote:
I just noticed this very tall alder tree is totally infested with something that is making holes in the leaves.

I scanned the leaves I picked and am asking if these are eriophyid mites, the only reasonable mention I found when I googled alder pests!

The pockets are on the leaf underside - but I expect that whoever is inside these pockets makes its living eating the leaf and then escaping to live another day!