266 TRANSFORMATIONS OF INSECTS. 



of the perfect insects. The beetle or perfect insect usually passes 

 a short existence. 



There is great diversity amongst the Colcoptera, both as regards 

 their anatomy, physiology, development, and the manner in which 

 they live. Many appear to be inferior or lower in the insect scale 

 than others ; whilst some are so elaborately constructed that they 

 must be placed in the most perfect class. The most decided 

 anatomical differences, so far as the internal organs are concerned, 

 coincide with striking distinctions in the external conformation of 

 the insect ; and in those beetles whose limbs denote superior 

 powers the nervous system is very concentrated ; and it is less so 

 in those species the structures of which are more simple. The food 

 of the Colcoptera is of all kinds, so, of course, the modifications 

 of the structures of the digestive organs are very great. Many 

 of the larvae are leaf-eaters, and certain kinds do a great deal of 

 harm to all sorts of crops and trees. There is much interest 

 attached to the early conditions of the Coleoptera, and there is often 

 a striking resemblance between the larvae of those families, the 

 adult forms of which differ in the strongest possible manner. In 

 some families of beetles the development of the larvae is very 

 slight, and they have no legs, so that they look like worms. In 

 other families the larvae have structures which are intended to act 

 as legs, but they are feebly developed, and locomotion is there- 

 fore very imperfect. On the other hand, many larvae are born 

 so fully formed, that they are very much like the perfect insects, 

 and are more or less active in their habits ; and, finally, some on 

 leaving the egg possess the habits and the methods of movement 

 which characterise the perfect forms. They cannot fly, however. 

 All these insects, more or less well organised, must undergo their 

 principal metamorphosis during the period of rest and quietude 

 when they are nymphs. The metamorphoses, the habits, and the 

 instincts of many of the Colcoptera are well known, and those of 

 a considerable number of species in each of the great groups into 

 which these insects may be divided have been carefully studied. 



There are at least twenty families of the Colcoptera which can 

 be readily distinguished on account of their members being very 

 characteristically formed ; but it is impossible, from what we know 

 at present, to collect them into groups, and to distinguish one from 



