Now that I’m aware of the existence of the Gelis wesp, see here, all ants in the garden are suspects. Scanning the ground for early insects awakening after the winter I notice a very small ‘ant’ crawling on a stone wall. And for sure it has an ovipositor. It manages to escape in a gap between the stones. With the sucker still ready in position but without hope she will appear again I give up after 20 minutes. At that moment a larger ‘ant’ comes crawling up a leaf behind the wall and it is immediately clear to me it is a Gelis. The sucker doesn’t fail so the identification process can start.

It turns out to be a female Gelis spurius ^[1,2] (confirmation Paul Hoekstra), a common species.

References