Its large size and the bright red bands around its body make it unmistakable; its coloration is aposematic, reflecting its ability, in common with other oil or blister beetles in the family Meloidae, to squirt a caustic liquid if attacked.

Populations of entirely black specimens without any red markings are found scattered over much of the distribution range of B. majalis.

[3] The red-striped oil beetle is found in dry places in Portugal and the Mediterranean regions of Spain and North Africa, from Morocco to Tunisia.

They live in sunny, dry places, either in open grassland in woodland with light tree cover.

The female lays between 2000 and 10000 eggs, but most of these fail to reach maturity either for lack of food or through predation.