Northern dune tiger beetle  (Cicindela hybrida)

Information supplied by English Nature:

http://www.englishnature.org.uk/

Larvae: stage in an animal's lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
Mandibles: the pair of mouthparts most commonly used for seizing and cutting food, common to the centipedes, millipedes and insects.