My eye caught a small, nervously wandering wasp that started digging near a low thistle on the digger wasp hill. The dotted abdomen followed by the thornlike protrusions of the metanotum disclosed this was a digger wasp from the genus Oxybelus, a female Oxybelus bipunctatus . It is the first time this common species has been observed in the garden, a new garden species!
She has dug nervously for some time in the sand of the hill, starting with two holes that were then connected by a short, shallow tunnel, followed by the deepest and largest hole behind a small rock. This larger hole, which seemed to be targetted to be the nest judging on the effort she put into it, collapsed multiple times during excavation and that might have been the reason she eventually gave up and disappeared.
References1 Nederlands Soortenregister