334 ENTOMOLOGY 



that kings of one colony of Stenamma when introduced into 

 another colony are even cordially received. 



Some of the most careful students of the habits of ants agree 

 that these insects can communicate with one another. An ant 

 discovers a supply of food, returns toward the nest, meets a 

 fellow worker, the two stroke antennae and then both start 

 back to the food; before long other members of the colony 

 swarm to the prize. It has been thought that the odor of the 

 food or some other odor, left by the first ant, serves as a trail 

 for the other ants to follow. Bethe, indeed, infers from his 

 experiments that this phenomenon is purely mechanical and 

 involves no psychical qualities on the part of the ants. His 

 own experiments, hqwever, show that one ant can inform an- 

 other by means of an odor as to the whereabouts of food 

 which is certainly one form of communication. 



Ants avoid sunlight as a rule but prefer rays of lower re- 

 frangibility to those of higher. Upon exposing ants to the 

 colors of the spectrum, as transmitted through glasses of dif- 

 ferent colors, Lubbock found that they congregated in greatest 

 numbers under the red glass and that the numbers diminished 

 regularly from the red to the violet end of the spectrum, there 

 being very few individuals under the violet glass. 



Miss Fielde, experimenting with queens, workers and young 

 of Stenamma fulvum piceum in an artificial nest, covered half 

 the nest with orange glass and half with violet. " The ants re- 

 moved hastily from under the violet as often as an interchange 

 of the panes was made, once or twice a day, for about twenty 

 days. Thereafter they became indifferent to the violet rays." 

 '' The plasticity of the ants is remarkably shown in their grad- 

 ually learning to stay where they were never disturbed by me, 

 under rays from which their instincts at first withdrew them." 



Ants are sensitive not only to the different colors of the 

 spectrum but also to the ultra-violet rays, which produce no 

 appreciable effect on the human retina (though they induce 

 chemical changes) . If obliged to choose between the two, ants 

 prefer violet to ultra-violet rays, as Lubbock found. If, how- 



