PERSECUTED AND TOLERATED GUESTS. 



plcctus and Ecito.vcnus, and the symphiloid genera Ecitogaster and 

 Ecitodulus. These correspondences between the guests of the Old 

 World driver ants and those of the New World legionary ants represent 

 a very interesting case of convergent development, for none of the 

 genera is common to both hemispheres and all of them have the appear- 

 ance of having developed independently in adaptation to their respective 

 hosts. The most remarkable mimetic form is Mimed ton pnlc.v, which 

 lives with the Brazilian Eciton predator. But the smaller Ecitons of 

 the Southern States also have their mimetic guests (Ecitonidia wheeleri 

 and Ecito.vcnia brevipes with Eciton schmitti, and Ecitonusa schmitti 

 and jor ell with E. carolinense}. As the 

 Doryline ants are blind, but endowed 

 with a very keen contact-odor sense, 

 Wasmann assumes that the guest's mim- 

 icry in form and pilosity is for the pur- 

 pose of deceiving its hosts, whereas its 

 color mimicry may enable it to remain 

 unseen by birds and other enemies while 

 it is moving along in the procession of 

 the ants. While Wasmann is probably 

 right in regarding the peculiar resem- 

 blance between guest and host as due to 

 a tactile mimicry, further speculation had 

 best be postponed till the insects can be 

 carefully observed in their natural 

 environment. 



The tendency to develop mimetic, loricate and symphiloid charac- 

 ters is not confined to the guests of the driver and legionary ants, but 

 is discernible also among the guests of many of our northern species. 

 Two of the common Staphylinids living with Liometopnm occidcntalc 

 in Colorado, namely, Dinardilla liometopi and Apteronina schmitti, are 

 clearly mimetic, the former in color and pilosity, the latter -in form. 

 In the species of Dinarda of Europe, we have guests which resemble 

 the loricate dorylophiles and ecitophiles in form and also mimic their 

 hosts in color. The genus has been carefully studied by Wasmann 

 (igoie, 19040?, etc.), who regards it as representing a series of forms 

 actually in process of speciation. The various Dinardcc have definite 

 hosts: D. dentata living with Formica sanguined, mcerkeli with F. nifa, 

 Jwgcnsi with F. e.vsecta, pygmcca with F. fusco-rufibarbis, nic/ritoidcs 

 with F. fnsca, and niyrita with Aphcenogaster testaceopilosa. D. den- 

 tata, mccrkeli and hagensi are red and black like their hosts, pygmaa 

 is dark and nearly unicolorous like F. fusco-rufibarbis, nigritoides and 



FIG. 229. Hetccrius brunnei- 

 peniiis. (Original.) 



