18 Natural History of the Honeybee. 



tant means of communication, which Bethe has completely ignored, and even Forel and 

 other Myrmecologists have failed to appreciate. It readily explains the rapid congrega- 

 tion of ants (Myrmicinae) on any particle of food which one of their number may have 

 found, for the excitement of finding food almost invariably causes an ant to stridulate 

 and thus attract other ants in the vicinity. It also explains the rapid spread of a desire 

 to defend the colony when the nest is disturbed. This is especially noticeable in, species 

 of Pheidole, Myrmica, and Pogonomyrmex. It is the secret of being able in a short time 

 to catch ants like Pogonomyrmex molefaciens in great numbers by simply burying a 

 wide-mouthed bottle up to its neck in the mound of the nest. An ant approaches and 

 falls into the bottle. It endeavors to get out, and, failing, begins to stridulate. This afc 

 once attracts other ants which hurry over the brim and forthwith swell the stridulatory 

 chorus till it is audible even to the human ear.' More ants are attracted, and soon the 

 bottle is filled. If it be corked and shaken for the purpose of still further exciting its 

 contents, and then held over another Pogonomyrmex colony whose members are peacefully 

 sauntering about on the dome of their nest, the wildest excitement will suddenly prevail, 

 as if there had been a call to arms or — to dinner. Even more remarkable is the stridula- 

 tion in a colony of Atta fervens, the Texan leaf-cutting ant. Here the different ants, 

 from the huge females through the males, large soldiers and diminishing casts of workers 

 to the tiny minims, present a sliding scale of audibility. The rasping stridulat^on of the 

 queen can be heard when the insect is held a foot or more from the ear; to be audible 

 the male and soldier must be held somewhat closer, the largest workers still closer; whereas 

 the smaller workers and minims, though stridulating, as may be seen from the movements 

 of the gaster on the postpetiole, are quite inaudible to the human ear. It is not at all 

 improbable that all this differentiation in pitch, correlated as it i3 with a differentiation 

 in the size and functions of the various members of the colony, is a very important factor 

 in the co-operation of these insects, and of ants in general. The contact-odor sense, impor- 

 tant as it undoubtedly is, must obviously have its limitations in the dark subterranean 

 cavities in which the ants spend so much of their time, especially when the nests are 

 very extensive like those of Atta. Under such conditions stridulation and hearing must 

 be of great service in maintaining the integrity of the colony and^ its excavations. The 

 fact that as yet no unquestionable auditory organs have been discovered in ants is of 

 secondary importance when it can be so easily shown that these insects really respond 

 in an adaptive manner to the sounds produced by other members of the colony." 



I know very well that Miss Adele M. Fielde and George H. Parker are of the opinion 

 (The Keactions of Ants to Material Vibrations, Proc. Acad. Nat. Sc, Philadelphia, Sept., 

 1904) that "it is misleading to ascribe or deny hearing to ants; they are very sensitive 

 to the vibrations of solids, not to those of air; their reactions could be as appropriately 

 described as resulting from touch as from hearing." But the above investigations on 

 bees have been neglected by these authors, and I am still of the opinion that a sensitive- 

 ness to the vibrations of air can not be denied so far as bees are concerned, and the 

 above experiments of Wheeler seem to show the same in ants. 



