ARID AGRICULTURE. 271 



crops or useful plants, but we know now that 

 thev do other things which make them enemies to 

 agriculture. The one useful thing which ants 

 apparently do is to serve as an example of indus- 

 try to the sluggard. 



The western mound-building ant truly loves 

 the desert. She builds mounds of small gravel 

 and does not allow any vegetation to exist for 

 some distance around her home. On the range 

 and in new fields, before this ant becomes dis- 

 couraged by cultivation and drowned by irriga- 

 tion, she occupies much space that should be oc- 

 cupied with grass or crop. Each one carries a 

 pair of scissors and industriously cuts off every 

 sprouting grain or small plant as fast as it comes 

 up. 



Ants are destructive nuisances around dwell- 

 ings or in yards. They will discourage or bother 

 colonies of bees by robbing the hives of their 

 honey. Another thing which ants do that causes 

 incalculable damage is to harbor and foster plant 

 lice. Plant lice excrete as foecal matter a sweet 

 fluid called honey-dew. The ants are very fond 

 of sweets and they actually rear and care for the 

 plant lice in return for the food product. Some 

 ants carry the plant lice eggs into their nests in 

 the fall, give them careful storage thru the win- 

 ter and in the spring place them on roots or ten- 

 der shoots of plants where they can begin the bus- 

 iness of supplying honey-dew to the ants as soon 

 as thev hatch. In other cases the ants care for 



