The video shows how the parasitic wasp Leucospis dorsigera thrives his ovipositor into hard wood in order to place the egg into a cell of the Hornet Mason Bee, Osmia cornuta. The nest inside the wooden block was built and provisioned in April. In contrast Leucospis is a summer species and searches for bee nests with larvae on which the egg will be deposited. The wasp larva feeds on the bee larva. The adult waps emerges in the following year.