INTERDEPENDENCE OF ORGANISMS 



17 



head 



thorax 



abdoMcn 



whether there exists any correlations between bilaterality, 

 position of the flower in the cluster, arrangement of the 

 stamens, etc. 



2. The adaptation of insects to flower visitation. 



In the body of an in- 

 sect there are three prin- 

 cipal divisions: head, 

 thorax and abdomen. 

 The head bears eyes, 

 antennae and mouth- 

 parts, the latter con- 

 sisting of upper and 

 lower lips, with two 

 pairs of jaws working 

 horizontally between 

 them. 



Fig. 10. Diagram of the externa] parts of an 

 insect, a, antennae; £", eye; oc, ocelli; /, pro- 

 thorax; //, mesothorax; ///, metathorax; 

 w, and Wo, fore and hind wings; /j, U, /j, 



fore, middle and hind legs; i, 

 segments of the abdomen. 



3, 4. etc. 



The thorax is di- 

 vided into three 

 horny rings or seg- 



of 



pair 



the 



two 



ments, each 

 which bears a 

 of legs, and 

 hindmost 

 bear each a pair of 

 wings. The abdo- 

 men consists of a 

 variable number of 

 segments. 



The accompany- 

 ing diagram (fig. 10) 



will serve to repre- pj(, ^ Mouthparts of grasshopper and beetle, a, 

 „p„j. ij-p arrancrp- ia.ce\[ie-woigras?,hopper{Melanoplus femur-rubrum) 



ment of parts for 

 insects in general. 



showing at /, labrum; b, labium of same; c, mandi- 

 ble of same; d, maxilla of same; ^.mandible of 

 soldier beetle (C"/iaM/zogna</iz<5 scutellaris) \ /.maxilla 

 of same, showing pollen brushes. 



