294 INSECT ARTIZANS AND THEIR WORK 



householder and burglar, as if each were doubtful 

 of the attitude of the other, but it ends in Sceliphron 

 allowing Larrada to carry out her plan. This 

 looks like another failure of instinct. There is no 

 room for reasoning in the matter, for none of 

 these wasps has any inherited knowledge of what 

 happens to her offspring, and the grub that suffers 

 from such dishonest proceedings never survives to 

 transmit the knowledge to descendants. 



Perhaps one of the most audacious examples of 

 these burglarious practices is afforded by the 

 habitual, everyday conduct of the little yellow ant 

 Solenofsis fugax. This ant seeks out a nest of 

 Formica fusca, an ant twice its size, and constructs 

 its own galleries in the walls of fusca's habitation. 

 From these galleries it makes entrances into the 

 chambers of the larger ant and lives cheaply at the 

 expense of Formica on its grubs and chrysalides. 

 It might be inquired, why do the larger ants permit 

 this ? There appears to be only one reason, and 

 that is that their superior size puts them at a 

 disadvantage. When in danger of being caught 

 the smaller ants slip through their minute holes 

 and tunnels where Formica cannot follow them. 

 Forel says that these entrances and exits are so 

 carefully contrived that they only just permit the 

 passage of the Solenopsis. 



One might suppose that from living for geriera- 

 tions in such close proximity, some sort of friendli- 

 ness would have been established between the two 

 species ; but that is not so. When they chance to 



