344 



THE ANIMAL KINGDOM 



Figure "17.17. A nocturnal insect, flying a straight path, uses the lamp (L) as a land- 

 mark when it comes into view (position A). Since the lamp is not far away the insect must 

 repeatedly turn to maintain a fixed bearing. (After Buddenbrock.) 



it and go to sleep, unless eaten by a bat or frightened away. Fright 

 appears to be the only stimulus that can break up the impasse. 



These are but a lew oi the relatively simple responses that can be 

 found abundantly in arthropods. There are, in addition, many complex 

 and less well understood patterns. The most elaborate of these are 

 social, in which the stimuli include others of the same species. Social 

 responses are well developed in the social insects, those that live to- 

 gether in colonies. 



155. Social Mechanisms in Insects 



The development of integrated colonies is limited largely to insects, 

 and a division of labor among the members of the colony is found only 

 in the termites, ants and bees. These colonies are marked by a restriction 

 of the function of reproduction to a limited portion of the population 

 and by a separation of duties among the nonreproductives. 



Termites. The termite colony (Fig. 17.18) begins when a pair of 

 winged primary reproductives shed their wings and set up housekeeping. 

 The young which they raise are sterile wingless workers, who do all 



