PERSECUTED AXD TOLERATED GUESTS. 



395 



nibbling at or even approaching the ant's head. It is always alert, as 

 if perpetually aware of danger and ready to dodge at the slightest 

 movement of the ant. Occasionally, in the narrow confines of an 

 artificial nest, the ants do succeed in capturing and devouring one of 

 their vigilant little nest-mates, but the fact that of the eleven sound 

 crickets remaining after these observations were made, eight were still 

 alive June 22, when I had to discontinue my observations for the 

 summer, shows that the crickets are extremely expert in keeping out 

 of danger. During all this time the attitude of the ants towards the 

 M\rineco[>hila remained unchanged, so far as I could observe. The 

 ants are compelled to tolerate the little crickets for a very simple reason. 

 The former, with their long bodies, incapable of much lateral flexure, 

 always walk or run in long straight or sinuous paths, and are quite 

 unable to turn around abruptly, whereas the stout-bodied crickets move 

 in a complicated zigzag path made up of very short lines and abrupt 

 angles. This seems to be the key to the symbiosis of the two insects: 

 they manage to get on together in the limited space of an ants' nest 



FIG. 234. Myrmecophilous cockroach (Attaphila fitngicola) from fungus garden 

 of Atta texana. (Original.) A, Male, dorsal view; B, female, dorsal view: C, 

 same, ventral view. 



because they have very different and, as it were, interdigitating modes 

 of progression. Since the ants are quite able to clean themselves and 

 one another and even take delight and spend much time in this employ- 

 ment, they probably derive little or no advantage from the crickets. 

 The latter, while deriving much of their sustenance from the surfaces 

 of the ants, are often seen haunting even the galleries abandoned by 

 their hosts, scrutinizing the walls and nibbling at them from time to 

 time. There can be no doubt that they find here the same substances 

 which cover the ants, for the walls of the galleries of a populous nest 

 soon become greasy from the attrition of the constantly passing ants. 

 Sometimes the crickets may be seen nibbling at dead ants that have 

 been temporarily abandoned in the galleries or placed on the kitchen 

 midden. 



