ADAPTATION 239 



species the benefits which free-living individuals must secure for 

 themselves. Association within the species may be limited to the 

 mere banding together of individuals as in herds of grazing animals; 

 such association does not reduce the potential indc^pendcnce of 

 the individual but gives him the protection of numbers. Carnivo- 

 rous species may run in packs, like wolves. Lull characterizes 

 this arrangement as "a sort of armed truce, the idea of mutual aid 

 for defense evidently being foreign to their code of ethics, for they 

 will at once turn upon, destro\^, and devour one of their own band 

 who happens to be wounded, even though it delay the chase." 

 Crows flock together apparently for no other end than companion- 

 ship, although they probably derive some measure of benefit in 

 the possibility of more certain warning of danger. 



Communal Associations. Such associations are accompanied 

 by a division of labor and in most animals by some structural 

 specialization of the different castes. Among the insects the ter- 

 mites (Order Isoptera) and ants, bees and wasps (Order Hymen- 

 optera) include many highly developed communal forms. The 

 condition found in the honey-bee colony is a relatively simple 

 illustration of communal association, since the number of forms 

 involved is only three (Fig. 5), many less than in the ants and 

 termites, although the division of labor is intricate and no indi- 

 vidual can long exist independently. 



The honey-bee colony is made up of a single queen, many 

 workers, and during the breeding season some drones. The queen 

 is a perfect female. She alone mates and lays eggs under normal 

 conditions, and she must even be fed by the workers. The worker 

 caste in a strong colony of Italian bees may include 100,000 or 

 more individuals, although a wild colony is likely to be much 

 smaller. During the winter under natural conditions there are 

 less workers present. These insects are females, but they are im- 

 perfectly developed and never mate. They are capable of laying 

 eggs under abnormal conditions, but these eggs can develop only 

 into drones, which always come from unfertilized eggs. The 

 drones are males, and are tolerated only during the breeding 

 season. In the fall they are killed by the workers or thrust out of 

 the colony to die. There is definite structural difference between 

 each of the three forms and in addition a division of labor not 

 wholly correlated with structural differences. Workers, when 

 newly emerged from the pupa, are idle for a few days. They then 



