294 A BOOK OF INSECTS 



while many exotic ants have a specialised worker caste 

 known as " soldiers." These, like the ordinary workers, 

 are imperfectly developed females, but they have excep- 

 tionally large heads and mandibles. In the case of the 

 " honey-ants," of which a number of species are known, 

 certain of the workers sacrifice their activity in order 

 to act as living food reservoirs. The Mexican species 

 (Myrmecocystus melliger), as observed by Dr. H. C. 

 McCook, sends out workers at night to collect the sugary 

 exudations of a certain oak-gall. On their return, the 

 foragers pass this substance on to other workers, which 

 hang sluggishly from the roof of little chambers in the 

 nest. The crops of these " honey bearers " eventually 

 become enormously distended, so that the whole abdomen 

 looks like a small translucent fruit. Apparently the sole 

 object of this extraordinary habit is to preserve the food 

 until such time as it shall be needed by the community. 

 Very little is known as to the origin of castes among 

 ants ; but the evidence, so far as it goes, points to 

 the conclusion that the differences are due to the 

 quantity and kind of food which the lame receive 

 from their nurses — as is known to be the case with 

 hive-bees. 



Ants excel all other animals in their devotion to 

 the rising generation. The queens of the nest are fed 

 and tended by the workers, and the eggs which they lay 

 are assiduously collected and carried off. But the eggs 

 are not kept permanently in isolated cells. They are 

 constantly moved from one part of the nest to another, so 

 that the most favourable conditions for their development 

 may be secured. Still greater care is bestowed upon the 

 larvae. They are fed by the workers at regular intervals, 

 cleaned, classified according to age, and carried from 

 chamber to chamber with never-failing solicitude for their 



