CHAPTER XIX 



Order Coleoptera : Beetles 



(Gr. KoXeos = a sheath ; Trrepov = wing). 



The beetles are an enormous group of insects in which the 

 front wings are hard and useless for flight but form covers, 

 or elytra (eXvT/aoi/ = sheath or shard), that cover the hind 

 wings and the back ; sometimes the elytra are soldered 

 together, sometimes they are short and leave the after part 

 of the abdomen exposed. The hind wings, which are 

 properly functional, are large and membranous, and have 

 few veins. The mandibles, maxillae, and labium are used 

 for biting, and in general form are not unlike the same 

 parts of a cockroach {cf. Fig. 112). The antennae vary in 

 structure and are used by systematists in classifying the order. 



All 3 segments of the thorax are distinct, though the 

 mesonotum and metanotum are covered by the elytra. 

 The form of the sockets of the legs, or coxal cavities, is of 

 taxonomic importance; they are said to be "closed" when 

 they are complete rings, "open" when they are merely 

 bights in the after -edge of the sternum. The coxae of the 

 hind legs are often broad plates which appear to belong 

 to their sternum. The number of tarsal segments is variable, 

 and is employed in classification. 



The larva usually has a distinct head, 3 distinct thoracic 

 segments, and 9 (occasionally 10) abdominal segments : 

 there are commonly three pairs of thoracic legs ; but legs 

 are often altogether absent. A majority of beetle larvae 

 live concealed in wood and among roots, and these, as a 

 rule, have a soft, whitish abdomen ; but some larvae are 

 active and predaceous, and have the abdomen shapely. 



The pupa also is usually buried in earth or timber ; it is 



