ANT COMMUNITIES 



them and fleeing with them in predatory raids all this 

 forms a chapter of natural history so strangely analogous 

 to the ways of agricultural society as to link the ancient 

 and wide-spread human interest in ants with the life 

 of the aphids, which lend themselves so readily to their 

 remarkable uses. This natural adaptation is, of course, a 

 factor in the development of the habit which here has 

 commanded our attention. 



That which makes ants particeps criminis in the de- 

 struction wrought by aphids is the remarkable habit 

 which they have acquired of deliberately housing the 

 aphid eggs and raising therefrom the adult forms. From 

 their breeding-camps and nurseries they transport these 

 domesticated herds to the plants which they elect to 

 attack, whether on root or stem. There the aphids 

 at once thrust in their beaks and begin to draw out 

 the sap, which the canny " proprietors " appropriate as 

 honey-dew. It is thus indirectly, and not by any direct 

 injury inflicted upon plants, that ants become at times 

 injurious insects. Otherwise they take rank with the 

 benign insects, by aiding the fertilizing of blossoms by 

 their frequent visit- for nectar, and the formation and 

 shifting of tillable soil by digging out their subterranean 

 homes. 



Our attention must now pass from the communal 

 associations which have been established between ants 

 and alien insects to those existing between ants of sepa- 

 rate species. These are numerous and greatly varied, 

 and only a few typical cases can be considered here. 

 Among the consociated communes of ants there are few 

 whose relations are more interesting than those existing 

 between Myrmica brevinodis and Leptothorax emersoni. 

 The latter is a small species (much smaller than Myrmica), 



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