Gall?

Gall?

Observation - Gall? - UK and Ireland. Description: I thought it was just a bit of debris but it has now started to 'sprout' a fluffy white 'growth'. I'm guessing it's a wasp or fly gall but know nothing about these or how to ID them! It's on a Sycamore leaf and there's currently no obvious effect on the

I thought it was just a bit of debris but it has now started to 'sprout' a fluffy white 'growth'. I'm guessing it's a wasp or fly gall but know nothing about these or how to ID them! It's on a Sycamore leaf and there's currently no obvious effect on the upper side.