The Firebug, Pyrrhocoris apterus, is a common bug and easily recognizable due to its striking red and black colouration.
It looks similar to the Black and Red Squash Bug (Corizus hyoscyami) but it has a different colour pattern on its back.
Young Fire Bugs (nymph) look different from the adults (on the photos).
The young ones are more red than black and they lack the adult's black triangle and two big black dots on the back.

Bükk National Park, Hungary, 26 April 2019