26 Riley — Presidential Address. 



Such cases as this, of an animal having lost the instinct of feed- 

 ing, are extremely rare in nature, but the habit here has even 

 affected the structure, for the mandibles of the slave-makers have 

 lost their teeth and are useless except as weapons of war. 



Burial Grounds. — It would seem almost incredible, but there 

 is nevertheless good evidence that some species of ants habitually 

 form burial grounds for the dead. An esteemed friend and re- 

 liable observer, Mr. Henry G. Hubbard, informs me that he has 

 carefully studied the habits of a black mound-making ant in 

 Montana, {Formiai mbpoUta Mriyr), the mounds being made in 

 dry situations in the mountains. There are always burial pits 

 just outside the hill, connected with it by passages; and these 

 burial pits contain generally a double handful of dead ants, with 

 occasional fragments of other insects. They are made in firm, 

 hard soil, and consist of a clean neat chamber, sometimes as large 

 as one's two fists. In moist ground the same species of ant does 

 not seem to use the same method of burial. These facts are all 

 the more interesting as showing how the same species may develop 

 a local habit, as siihopolita is now considered but a variety or sub- 

 species of the widespread F. fusra L. 



Food-habits. — In Note 5, in speaking of the several species, 

 I have recorded iii detail some food-habits of our ants. Taken 

 as a whole they are truly omnivorous, feeding upon all sorts of 

 })lant and animal matter, storing" various kinds of vegetation, and 

 even, as in the case of the leaf-cutter ants, cultivating certain 

 fungus growths for food, but particularly relishing the sweets 

 obtainable from plants and other sources, and more especially 

 from the excrementitious and other secretions of plant-lice and 

 bark-lice. 



Keeping and raising KiNE.^There is no work upon ants 

 which does not refer to their well-known habit of guarding and 

 encouraging plant-lice, protecting them from their enemies, and 

 in other ways looking after their welfare. This attitude toward 

 various species of Aphidida? is essentially selfish, as these, 

 when carressed, yield a sweetened liquid which the ants much 

 covet. For this reason the Aphides have been denominated, in 

 popular parlance, the ants' milch-cows. Certain species of plant- 

 lice are frequently attended by particular species of ants, and 

 there is often a remarkable colorational harmony between a par- 

 ticular ant and the Aphidid colony which it cherishes. It is not 



