October, I'^no.] 



J'SYCHE. 



115 



It is an estal)lislied fact that ants when 

 moving to a new nest will take with them 

 certain of their guests like their Aphides, 

 and the singular beetles of the genera 

 Claviger, Paussus, etc. Myrmecophila 

 can lay claim to no such consideration. 

 When a colony of Formica nconijibarhis 

 moves, the crickets are all left behind. 

 The heavy floods of the past spring 

 gave me an excellent opportunity to con- 

 vince myself of the truth of this state- 

 ment. Many of the nconifibinhis nests 

 which I was in the halait of visiting, were 

 submerged during the night by a rapid 

 rise of one of the creeks near Austin. 

 The following day, when the water had 

 subsided, I found that the nests had 

 been completely deserted by the ants, 

 but nearly all of them still contained 

 numerous Myrmecophila wandering in 

 and out of the galleries under the stones 

 as if notliing had happened. I have also 

 seen the crickets left behind in other 

 ncunifibinbis nests which were on higher 

 ground and had been deserted for rea- 

 sons unknown to me. These observations 

 may explain a note quoted by Mr. Scud- 

 der concerning M. orcgoneiisis IJruner. 

 Dr. Fletcher informed him that this 

 species is " common in IJritish Columbia 

 under almost every slab of wood in some 

 places, whether there are ants there or 

 not." I doubt the occurrence of Myrme- 

 cophila outside of ants' nests. 



It is evident from the facts above re- 

 corded that the ants would gladly forego 

 the company of their little nest-mates, 

 but unless they resort to moving the 

 wiiole colony, they are compelled to 



tolerate them for a very simple reason. 

 The ants with their long bodies, incapable 

 of much lateral Hexure, always walk or 

 run in long, straight or sinuous paths, 

 and are quite unable to turn sharply 

 about, whereas the short-bodied crickets 

 move in a complicated zig-zag path 

 made up of very short lines and abrupt 

 angles. This seems to be the key to 

 the symbiosis of the two insects: the 

 ant and the cricket manage to get on to- 

 gether in the limited space of an ants' 

 nest 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 employment, they probably 

 derive little or no advantage from their 

 cricket guests. The crickets, however, 

 cannot get on without the ants and the 

 greasy walls of their burrows. The 

 symbiosis is thereforeof a unilateral type 

 and would seem to belong in the category 

 of relationships called "Metoekie" or 

 "Synoekie" by Wasmann. It is, in 

 fact, a relationship but slightly in ad- 

 vance of that of the Collembolan Cy- 

 pJiodcira {Bcckia) albinos Nic. which 

 appears to obtain its entire sustenance 

 from the walls of the ants' burrows with- 

 out extending its attentions to the integ- 

 ument of the ants. 

 University of Texas, 

 Austin, Tex., June 22nd, igoo. 



* Die Myrmekopliilen uiid Ternnlophilen, Compt. Rend, 

 des Stances dii .-jnle Collgr. internat. Zool. Jxyde 16-21 

 Sept. 1895. I.eyden. i8q6. p. 412. 



