1904] BRUES-. — MYRMECOPHlLES AXD THEIR ItOSTS 21 



ON THE RELATIONS OF CERTAIN MYRMECOPHILES TO THEIR 



HOST ANTS. 



BY CHARLES T. BRUES, COLUMBIA UNIVERSITY, NEW YORK CITY. 



Wasmann, to whom we owe the bulk of our knowledge concerning myrme- 

 cophiles, divides the series of staphylinid bettles which live with the legionary ants 

 into four biological groups.^ 

 These are, 



1. Mimicry Type. Including those which mimic, to a greater or less extent, 

 the color, form, actions and other characteristics of their hosts. 



2. Offensive Type. (Trutztypus.) Including those not fostered or 

 willingly tolerated by the ants, but living a precarious existence in their nests and 

 only escaping destruction through the ants' inability to capture them. 



3. Symphily Type. Including those which are tolerated on account of 

 some benefit which the ants derive from them, usually forms with glandular hairs 

 that secrete substances agreeable to the ants. 



4. Indifferent Type. Less specialized forms whose relations are not so 

 easily interpreted. 



It is about the first two types that I desire to confine my present remarks. 



We have naturally, not far to seek to find an explanation for the resemblance 

 between the ants and many of their guests. It is evidently advantageous for the 

 myrmecophiles to resemble their hosts in size, form, color, odor and any other attri- 

 butes which the ants are capable of perceiving. This is, I think, perfectly evident, 

 for all ants show the greatest good will toward the members of their own nest and 

 the more their guests approach their own kind in appearance the more readily they 

 are tolerated. 



This applies most strongly to myrmecophiles which depend to a greater or less 

 extent upon concealment for safety. Even in the case of forms which supply 

 pleasant secretions to the ants or are beneficial to them in other ways, it must enter 

 at least to some extent into their relations. Thus protected they may at times 

 either deceive the ants as to their identity and pass unnoticed, or at least attract 

 less notice than if they were entirely different from the ants in appearance. This 

 is evidently the chief value of mimicry to the guests living with ants which can 

 readily discriminate such objects as color and form. Among ants with a keen 



1 Verh. d. deiitschen Zool. Ges., 1902. p. 86. 



