This is a tiny little beetle and it has to be seen in good light to appreciate that it has red markings on its black elytra.
Anywhere a food source is to be found such as low vegetation or even on the sills of outbuildings etc. where tiny gnats and flies congregate. Often swept from long grass beneath trees.
When to see it
Best time is May and June.
Despite its size the adult is a predator of even smaller insects. The larvae of Anthocomus are predatory on the larvae of wood-boring beetles…. Naturespot