116 Other Inter-relations 



ning the web that makes the ants' nest; hence the 

 strange word hyphamosymphily, for "symphily" 

 means something like "friendly association" and 

 "hyphaeno" means "spinning." It is a mutually bene- 

 ficial association, as the result of which the cater- 

 pillars secure shelter and food, and the ants secure 

 assistance in nest-making. There is no trace of exuda- 

 tions which might give the caterpillars a pleasant 

 fragrance or taste, as in many ants' guests ; and the 

 caterpillars have no disguise or invulnerability or 

 quickness or protection of any kind. All that can be 

 said is that the ants tolerate the caterpillars, whom 

 they could devour in a very short time if they chose. 

 It seems to us that the caterpillars have by far the 

 best of the bargain. 



It would be strange if an inter-relation like this 

 stood quite alone; and it does not. Apart from the 

 presence of the caterpillars of a species of Wurthia 

 in the nests of the tailor-ant, where no assistance in 

 spinning has as yet been observed, there is a case 

 described by Jacobson where caterpillars of an unre- 

 lated moth (Batrachedra) live in the nest of another 

 kind of Polyrhachis ant and strengthen the wall with 

 their spinning. These ants are furiously intolerant of 

 other caterpillars, but they shut their eyes to this 

 one which devours their cocoons ! There is also a very 

 curious case where the caterpillars of another species 

 of Batrachedra live in a friendly way with a gregari- 

 ous South African spider and probably assist in the 

 strengthening of the web. These instances are inter- 

 esting, because they suggest steps in the evolution of 



