Beach and Dune - Gower - page 148

when few other areas of Wales received any attention from entomologists. The size of the dune systems
is important, as the larger complexes contain a richer range of habitats. The compacted sand of the ma-
ture dunes is ideal for burrowing insects and the rich flora supports a wide range of invertebrate prey for
sand-dune wasps, while the abundance of nectar sources ensures a plentiful food supply for bees. The
brown-banded carder bee Bombus humilis , in particular, is common both in the dunes and on the south
Gowercoast.Despiteitsabundancehereitisactuallyoneofthemostendangeredspeciesofbumblebeein
Britain. The bee has a characteristic brown band on the upper surface of the abdomen, hence the common
name. It nests on the surface of the ground, usually in grass tussocks, and forages for pollen and nectar
throughout the summer months from May to September.
The real specialities of the dunes are the predatory insects, which include the robber fly Pamponerus
germanicus (Fig. 79) and the stiletto fly Dialinura anilis . The robber flies typically frequent sand dunes
just behind the marram grass belt and feed on other insects, some flying in search of food while others
lie in wait and pounce on their prey. The proboscis of these flies is very hard and is used to pierce the
prey and suck its juices. Their larvae are thought to develop in moist sand as predators of other inver-
tebrates. At night the large black, smooth ground beetle Broscus cephalotes emerges from under stones
and driftwood to feed in the sand dunes, preying particularly on amphipods and isopods. During the day
it is replaced by the nationally scarce dune tiger beetle Cicendela maritima , whose British stronghold is
Wales, with records as far north as Morfa Harlech. In contrast, elsewhere in Europe it is a common and
widespread species that is not always restricted to the coast. The tiger beetle has an annual life cycle,
breeding in spring and summer and overwintering as pupae or adults in burrows situated in hard-packed
sand.
FIG 79. The robber fly Pamponerus germanicus , a common predator of the Gower dunes. (David Painter)
Another striking insect is Britain's largest bush-cricket, the great green bush-cricket Tettigonia viri-
dissima (Fig.80).Despiteitsloudsongthisbrightgreeninsect,whichgrowsupto5centimetreslong,can