ANTS — KEEPING- PETS. 83 



to deposit more balls upon and around the domiciles of their 

 tiny neighbours than elsewhere. The erratics struggle vigor- 

 ously against this Pompeian treatment; they bore through 

 the avalanche of balls, only to find barriers laid in their way. 

 The obstructions at length become so serious that it is impos- 

 sible to keep the galleries open. The dwarfs cease to contend 

 against destiny, and, gathering together their household stores, 

 quietly evacuate the premises of the inhospitable giants. It is 

 the triumph of the policy of obstruction, a bloodless but effec- 

 tual opposition. 



Lastly, MacCook records the history of an interesting 

 engagement which he witnessed between two nests of 

 Tetramorium ccespitum. It took place between Broad 

 Street and Penn Square in Philadelphia, and lasted for 

 nearly three weeks. Although all the combatants belonged 

 to the same species, however great the confusion of the 

 fight, friends were always distinguished from foes — ap- 

 parently "by contact of antennae. 



Habit of keeping Domestic Pets, — Many species of 

 ants display the curious habit of keeping in their nests 

 sundry kinds of other insects, which, so far as observation 

 extends, are of no benefit to the ants, and which there- 

 fore have been regarded by observers as mere domestic 

 pets. These ' pets ' are for the most part species which 

 occur nowhere else except in ants' nests, and each species 

 of ' pet ' is peculiar to certain species of ants. Thus 

 Moggridge found ^ a large number of a minute shining 

 brown beetle moving about among the seeds ' in the nests 

 of the harvesting ant of the south of Europe, ' belonging 

 to the scarce and very restricted genus Golnocera, called 

 by Kraatz C. attce, on account of its inhabiting the nests 

 of ants belonging to the genus Atta.^ He also observed 

 inhabiting the same nests a minute cricket ' scarcely 

 larger than a grain of wheat ' (Gryllus myrmecophilus), 

 which had been previously observed by Paolo Savi in the 

 nests of several species of ants in Tuscany, where it lived 

 on the best terms with its hosts, playing round the nests 

 in warm weather, and retiring into them in stormy weather, 

 while allowing the ants to carry it from place to place 

 during migrations. Again, Mr. Bates observes that 



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