With something in the region of a quarter of a million species, the beetles are by far the largest group of insects. Rather more than 4,000 species are known in the British Isles but, although many of them turn up in the garden from time to time, very few are in any way restricted to garden habitats.Beetles are generally recognised very easily because the front wings are hardened and modified into protective shells called "elytra". These elytra usually cover the whole abdomen, but they are very short in "Rove Beetles" and they are absent altogether from the female "Glow-worm". Only the hind wings are used for flight, but most beetles prefer to keep their feet firmly on the ground or on the vegetation and they don't very often fly. They scuttle away when disturbed, or else they just drop to the ground and play possum (lie still), with their legs held tightly against the body. Many beetles have no hind wings at all, and their elytra are fused together and immovable. It is possible that some of the beetles will be confused with the "Heteropteran bugs" to start with, but the elytra of the beetles always meet and form an obvious junction in the mid-line, whereas those of the bugs always overlap. In addition, the beetles all have biting jaws and never have the piercing beak which is so obvious in the bugs.
Beetles can be found almost anywhere, for their tough elytra give them added protection and allow them to occupy places which are denied to other winged insects. Many of them, for example, live in the soil and under stones, while others spend their lives groping their way through piles of stored grain and flour. Water beetles use the spaces between their elytra and their bodies as rechargeable air cylinders which enable them to spend long periods under the water. Associated with their wide range of habitats, the beetles also make use of a very wide range of foods, both animal and vegetable, living and dead. Many have a remarkable metabolism which enables them to survive without free water, and it is this ability which has led to the establishment of grain weevils, carpet beetles, and other species as pests in food stores and domestic premises. In general, the larvae of the beetles eat much the same kind of food as the adults, and both stages therefore cause damage. The larvae themselves are very variable, ranging from the very active young of the ground beetles to the legless grubs of the weevils. Most of the plant-feeding beetle larvae are rather stout and slow moving, bearing three pairs of legs at the front of the soft and often brightly coloured bodies.
One group of beetles stand apart from the others which are found in the garden and which can be found indoors. This group is known as the Ground Beetles. These beetles are fast moving and very predatory. They have long legs and a characteristic angular shape. They also bear fine sensory bristles on various parts of the body, but these are not easily seen without a lens or at least close examination. Many ground beetles have a beautiful metallic sheen when seen from certain angles, but the majority are of a sombre hue and generally look black when seen in the garden. The best way to see ground beetles is to go out with a torch at night, they can be seen hunting slugs and other tasty morsels.
