HYMENOPTERA 153 



Workers are infertile females not fully developed. There 

 may be different sizes of workers, the soldiers themselves 

 being workers with greatly developed heads and jaws. Ants 

 have a wide variety of food habits and live in greatly different 

 situations. Some burrow in the ground, others in wood; some 

 construct nests on the stems of plants. Many ants are 

 almost omnivorous, but most species have a weakness for 

 sweets of all sorts. This fact often renders them very 

 annoying and destructive in dwellings. Some ants are 

 farmers or harvesters. They are often called agricul- 

 tural ants and are popularly, but erroneously, supposed 

 to plant the crops which furnish their food. Several ants 

 have the habit of making slaves of the workers of other 

 species. In some the slave-making habit is of such long 

 standing that they have forgotten how to care for their 

 own nests, and when they cannot obtain slaves they perish. 

 Much has been written about the communal organiza- 

 tion found in ant colonies and many writers ascribe to 

 ants intelligence of a human order and altruism of an 

 even higher degree. Undoubtedly, ants do possess very 

 highly developed instincts; their colonies are well organized 

 and their daily functions are performed in a most efficient 

 manner. At the same time there is, in the mind of the 

 writer, ample proof that the first gleams of anything that 

 may be called intelligence has yet to appear in any insect 

 type. The basis for the assumption that ants possess 

 intelligence has been the difficulty of explaining certain of 

 their actions on the ground of instinct alone. There are 

 other actions that are even more difficult to reconcile with 

 the idea that these insects have the slightest intelligence, 

 and added to that is the physiological reason of the lack 

 of a structure comparable to the brain of the thinking 

 animal. 



