Ooh, superb. These are the larva of one of the Oil beetle species, Meloe spp., and are known as triangulins. The female oil beetle lays her batch of eggs in the soil, when these hatch the triangulins leg it up a nearby plant (hopefully with flowers) and await the arrival of a bee. They then rush the bee and several will usual manage to grab hold of one of the bees hairs with their mandibles and be transported back to the nest of the solitary bee. (I do not think that honey bees or bumble bees are ever successful hosts). Once there the triangulin tucks in to the pollen resource provisioned for the bee larvae - nicking some bees provender in this way is known as cleptoparasitism. It's a fascinating life history and a once in a lifetime opportunity to photograph these. Thanks for posting.