1898] PARASITES A AW MESS-MA TES IN ANT-HILLS .327 



Sleep, so necessary to animals which expend so much energy, and 

 the noctural torpor, occasioned by cold, put ants at the mercy of 

 myrmecophagous coleoptera. One of these is Myrmoecia fassi of the 

 nests of Tcqnnoma erraticum, which hides itself during the day to 

 avoid the formidable poison of these ants, but which seizes and 

 devours them during the night. 



During their winter sleep ants are without means of defence. It 

 is said that the bird Picus viridis, which supports itself chiefly on 

 insects, digs up the nests of Formica rufa in the winter and eats the 

 torpid inhabitants. 



The oreat multitude of individuals, and the almost incessant 

 renewal of the progeny, which contributes so much to the power of 

 ants, allows them, on the other hand, to become an easily found prey 

 for those animals which are stronger than themselves, or are so 

 organised as not to suffer from their means of defence. Thus it is 

 that ant-bears, birds, and toads destroy a considerable number of ants. 



Ant larvae, in common with the larvae of so many other insects, 

 receive the eggs of entomophagous Hymenoptera, which develop at 

 the expense of the tissues of their victim and undergo their nymph- 

 stage in the cocoon of the ant (EucJioris myrmeciae, the entomophage 

 of Myrmecia forficata). The difficulty that the entomophagous Hy- 

 menoptera have in penetrating to the interior of the nests, explains 

 the fact that the ant larvae do not more often fall victims to them. 



Finally, the abundance of progeny which is to be found in 

 ants' nests constitutes a choice of nutriment to every animal which 

 seeks first. Thus Solenopsis fugax, thanks to its small size, is able 

 to penetrate the nests of other species of ants to devour the nymphs. 



Societies of ants are rendered powerful by the number of indi- 

 viduals that compose them ; by their tenacity, courage, and complicated 

 instincts ; by the perfect means of attack and defence possessed by 

 certain individuals ; by the favourable medium and the protection 

 that is afforded by their well-shielded retreats ; and by a remarkable 

 division of labour. On account of all these particularly advan- 

 tageous circumstances, colonies of ants as a rule enjoy a long 

 existence and a life of opulence. 



