340 TEXT-BOOK OF ZOOLOGY 



first thoracic somite (prothorax), is of specially large size. (Contrast 

 with swimming and leaping insects.) Moreover, since the fore-legs 

 must be endowed with considerable mobility, the prothorax remains 

 free, instead of coalescing with the other thoracic segments. (This 

 is also the case in all other beetles, as well as in grasshoppers and bugs, 

 constituting the division of so-called " cursorial insects," all of which 

 employ their fore-legs actively in running, climbing, scraping, seizing and 

 mastering their prey, removing obstacles and loads, etc. Contrast with 

 these the " flying " insects : Lepidoptera (butterflies and moths), Hymen- 

 optera (bees and wasps) and Diptera (flies).) 



The dorsal portion of the chitinous covering of the first thoracic 

 segment (prothorax) is termed the pronotum. In the cockchafer it is 

 black or red, or appears whitish owing to a covering of short hairs. 

 When the wings of the beetles are not spread apart, only a small 

 triangular portion of the second thoracic segment, the so-called scutellum, 

 remains visible, being interposed between 



(/) The wing-cases, or elytra (see Section 2, a). These hard covers 

 protect the delicate wing membranes whilst the beetle is working its 

 way upwards through the ground. 



2. Adaptation for Flight. Having at last one evening reached the 

 surface of the ground, the cockchafer soars upward into the mild spring 

 air, and flies with a loud humming noise from tree to tree. 



(a) As is the case in all beetles, only the hind-wings are used as 

 organs of flight. The fore - wings have the form of horny plates, 

 brown in colour, their function, as already intimated, being to protect the 

 fine membranous hind- wings against injury. They are for this reason 

 described as wing-covers, or elytra. The hind-wings, being longer than 

 the fore-wings, are folded together in order to be completely hidden 

 beneath the latter. When preparing for flight, the cockchafer raises its 

 fore-wings somewhat and begins to breathe energetically, probably for the 

 purpose of laying up a store of air to be used during flight. (There can 

 be no question here about a diminution of the body weight ; see Part II. , 

 p. 145, note.) In Germany childre'n are accustomed to play with cock- 

 chafers, which are very common on the Continent. They sing a rhyme 

 when the insect is " counting " that is, making the respiratory move- 

 ments preparatory to flight just as children in England sing to the 

 ladybird : 



"Ladybird, ladybird, fly away home ; 

 Your house is on fire, your children at home," etc. 



The " spiracles " or stigmata (see p. 315) are situated above the five 

 white triangular spots of the otherwise black abdomen, in the fine 



