I found a small, brown spherical object, less than 1 cm, attached to a dead leaf on the oakwood floor at Clara Vale, Co Wicklow. When I broke one open it contained a tiny white grub.... Eamon Lynch, Dublin 15
These are marble galls caused by the gall wasp, Andricus kollari. This tiny, ant-like insect has two generations: one a sexual and the other an asexual generation. A parthenogenetic female will emerge from this gall in autumn and will overwinter in a sheltered spot. When she lays eggs on the buds of sessile or pedunculate oaks in spring the larvae will cause these marble galls on the leaves and the cycle will repeat itself. But if she lays the eggs in the buds of turkey oak, a bisexual generation will emerge in spring from much smaller galls.
On the causeway at Dollymount Strand, there are lots of wild flowers that attracted hundreds of an unusual insect. They were about the size of a bee, with wonderful dark red wings and a black body.
... Maureen Westbury, Dublin 5.
They could have been one of the burnet moths.