BEETLES 



341 



membrane which unites the hard ventral with the soft dorsal portions of 

 the abdominal somites. 



(b) The elytra (note their convex shape) are continued over the ivhole 

 dorsal surface of the abdomen as far as the anal style. Hence, this portion 

 of the abdomen, unlike all the other parts of the body, remains soft and 

 extensile. (Explain the importance of this in respiration.) 



(c) The body of the cockchafer is stout (see Section 3 d), and its centre 

 of gravity lies far behind the point of articulation of the wings. Hence, 

 during flight the beetle assumes an oblique position relatively to the 

 direction of flight, so that it presents a large surface to the air. For this 

 reason the cockchafer is but an indifferent flyer. Nor, when we consider 

 the nature of its food, does 



skill in flying, like that pos- UHLr-Kt. 



sessed by the bee or butter- ' 



fly (which see), seem to be 

 specially necessary in the 

 case of this insect. 



3. Food. — The food of 

 the cockchafer consists of 

 the leaves of fruit-trees, wil- 

 lows, oaks, beeches, horse- 

 chestnuts and other trees. 



(a) Its eyes, and more 

 especially its antennce, point 

 out to the animal where its 

 food is to be found. The 

 last six (female) or seven 

 (male) joints of the ten- 

 jointed antennae are widened 

 out into large plates or la- 

 mellae (lamellicorn beetles), 

 forming an elegantly-shaped fan, of which the remaining joints form the 

 handle. The larger number and size of these lamellae in the male 

 implies an enlarged surface, on which are situated the minute organs of 

 smell. This difference becomes comprehensible when we consider that 

 the male discovers the female by the sense of smell. (In what other 

 insects do we notice the same phenomenon ?) 



(&) Before commencing its meal, the cockchafer secures a firm hold of 

 the leaves by means of the sharp claws of the last joints of its toes. In 

 cool weather the beetle becomes rigid, so that the claws cease to act. It 

 may then be easily shaken off the tree, especially in the mornings after 

 cold nights. 



23—2 



Mouth Parts of a Beetle (Ground Beetle). 



01., Labrum ; Ok., mandible ; Uk., maxilla ; K., mas- 

 ticatory portion, Kt., palpus, of the maxilla ; 

 Ul. , labium ; Z. , its middle, anterior portion, or 

 tongue (lingua) ; Lt., labial palpi ; A., eye ; F.. an- 

 tenna. 



