554 INSECT A ORDER COLEOPTERA. 



which, called elytra, are of a horny or leathery consistency, and when closed, 

 form covers for the true wings, which are membranous, and are folded beneath 

 them like a fan, but with the end doubled back. They undergo a perfect 

 metamorphosis, the pupa being what is called necromorphous, or corpse-like, 

 because, although inactive, it is not enclosed in a single tight-fitting integu- 

 ment, like that of a butterfly or moth, but is furnished with separate 

 though immovable sheaths for the antennae, legs, etc. The mouth of 

 the perfect insect is mandibulate, or furnished with strong jaws or 

 mandibles. 



Beetles are very numerous. We are probably at present acquainted with 

 at least 150,000 species ; and although they have been more carefully collected 

 than most other orders of insects, there are, doubtless, 

 Number of enormous numbers which yet remain to be discovered. In 

 Species. Britain we have in round numbers about 3,000 species. 



They feed on all kinds of animal and vegetable substances 

 on land, in the water, and on the seashore ; but very few are parasitic on 

 other insects. They vary in size from an almost invisible speck to six inches 

 in length, or with expanded legs and antennae much more. Many of the 

 plant-feeding beetles, as the wire-worms, the chafers, the Colorado potato- 

 beetle, the turnip-fly, etc., are extremely destructive to our crops ; but the 

 carnivorous beetles, such as the ground-beetles, the tortoise-beetles, the 

 lady-birds, etc. , are very useful in destroying other injurious insects; and 

 the grubs of some of the large wood-feeding beetles are esteemed a great 

 delicacy in some countries ; indeed, it is far more probable that the Cossus of 

 the Romans was the larva of some large Lamellicorn or Longicorn beetle 

 than that it was the repulsive foul-smelling larva of the goat-moth, although 

 Linne* applied the name to the latter insect. 



In the classification of beetles, the structure of the antennae, wing-cases 



and legs is of primary importance. The neuration of the wings, which is 



important in some orders of insects, is not much used in 



Classification. Coleoptera. It should, perhaps, be noted that the wings 

 are sometimes wanting, when the elytra are sometimes free, 

 and sometimes soldered together at the middle line where they meet, which 

 is called the suture. Sometimes both wings and elytra are absent, either in 

 both sexes, or in the female only, as in that of the glow-worm. In some 

 beetles there is a triangular space, let in, as it were, between the bases of the 

 elytra ; this is called the scutellum. In some families the anal appendages 

 are useful in classification, while in others the structure of these parts is so 

 uniform that it is not worth noting in this connection. Ridges on the body 

 or elytra are called carinse, and circular pits (very conspicuous and numerous 

 in some species) are called punctures. 



The first large group of the beetles is that of the Geodephaya, or carnivorous 

 ground -beetles, which are divided into two main families, the Cicindelidce, or 

 tiger-beetles, and the Carabidce, or ground-beetles proper. They are hard- 

 shelled oval beetles, with long slender legs and antennae, and five-jointed 

 tarsi on all the legs. 



The tiger-beetles have a small moveable hook at the end of the maxillae, 



large heads, with very prominent eyes and strong jaws, and very long and 



slender legs and antennae. The front tibiae are not notched 



Tiger-Beetles, on the inner side. We have but one British genus, of which 



the green tiger-beetle, Oicindela campestris (Linn.), is the 



commonest species. It is found in sandy places, where its larva constructs a 



