Sphecodes is a genus of bees ithin the family Halictidae, the majority of which are black and red in colour and are colloquially known as "blood bees".
Sphecodes bees are cleptoparasitic on other bees, especially bees in the genera Lasioglossum, Halictus and Andrena.
The adults consume nectar and are polylactic, i.e. generalist feeders, but because they use other bees to bring up their offspring they do not collect pollen.

There are about 20 types of blood bees in the Netherlands, only 3 of which are common.
They are the most difficult bee species to identify.
Identification of blood bees from a photo is only possible for some species like Sphecodes albilabris which is bigger (1 - 1.5 cm) than most other species.

Naardermeer, Naarden, The Netherlands, 18 April 2019