192 THE BRITISH NATURE BOOK 



others the true wings are only rudimentary or even non-existent. The male 

 of the Glow-worm, for example, can fly, but the female has no wings or elytra. 



The hard, shell-like material which protects the soft inner body is called 

 " chitin," and is in reality the skeleton (technically, exoskeleton) of the insect. 

 The eyes are compound, though some species have two simple eyes in addition. 

 In some cases these compound eyes are divided nearly in two by a process on 

 the side of the head, as, for example, in some of the Water Beetles. 



It is, however, in the antenna that the most striking feature of beetles 

 is seen. These vary in shape in different species, and are thereby of great 

 use in classifying the species. They may be simple, thread-like forms, known 

 as filiform, serrate (or saw-like), pectinate (comb-like), capitate (with a head), 

 clavate (clubbed), lamellate (plated), geniculate (elbowed), etc. The foot also 

 is an important feature in classification. This (usually called the tarsus) has 

 generally five joints, on the last of which are a pair of claws ; but in many cases 

 it will be found that this number varies. The five-toed species form a large 

 section the Pentamera; a second group, the Heteromera, have five " toes " on 

 the first and second pair of legs, but only four on the third pair ; the Tetramera 

 have four " toes " to all their legs ; whilst the T rimer a have (apparently) only 

 three " toes " to a leg. 



The elytra that is, the wing-cases vary also in form. Some are grooved 

 or furrowed, these marks being known as sir ice ; others are covered with tiny 

 holes or punctures, which may be fine or coarse, deep or shallow. In many 

 cases beetles are clad in soft down, usually called " pubescence." 



The life-history is much the same as that of other insects. First the egg, 

 generally laid by the female in a selected spot where the larva can find food 

 without difficulty in the ground at the roots of trees, in pellets of dung, 

 rolled up in leaves, etc. The larva vary in the different species, some having 

 three pairs of legs, but others being entirely legless. Some have bodies pro- 

 tected by flat horny plates, others are quite soft and easily damaged. Some 

 reach their pupal stage in a few weeks, others remain as larvae for two or three 

 years. In the case of those which remain underground, feeding on roots, 

 it may be imagined how destructive they are. 



In the pupal stage some are encased in a cocoon, others suspended by the 

 tail, others remain hidden in the old larval skin, on or beneath the ground. 

 Whilst in this condition they take no food, but gradually darken in colour, 

 and finally, shedding a transparent skin, appear as soft beetles, very soon 

 hardening and assuming the perfect condition. 



As soon as the collector makes a start, he will be surprised at the many 

 varied colours of the species he captures, for beetles appear to be tinted in 

 almost every metallic hue green, blue, bronze, tinged with pink and yellow, 

 as well as brown, black, and grey. The species vary also in size from the 

 great Stag-beetle to the smallest, almost microscopic specimen that flies into 

 one's eye. 



Many, it is true, are injurious to plants and trees, feeding upon the roots 



