They occur in rocks that were originally formed in swamp and marsh habitats - where dragonflies pursue small flying insects, such as midges, gnats and moths, to eat. Libellulids survive today as the dragonflies known as darters or skimmers, most of which have a broad body flattened from top to bottom. Their typical behaviour is to rest on a waterside perch, watch for victims with their domed eyes their vision is among the sharpest in the insect world - and then dart out to catch the prey in a 'basket' formed by their six dangling legs.