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 coespitum. 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 Peis. — 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 c pets ’ are for the most part species which 
occur nowhere else except in ants’ nests, and each species 
of 6 pet ’ is peculiar to certain species of ants. Thus 
Moggridge found 6 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, 6 belonging 
to the scarce and very restricted genus Golnocera , called 
by Kraatz G . attce , on account of its inhabiting the nests 
of ants belonging to the genus AttaJ He also observed 
inhabiting the same nests a minute cricket 6 scarcely 
larger than a grain of wheat ’ ( Gryllus myrmecophilus ) 9 
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 
