THE TRIBE OF THE BLUES 261 



arrangement? If you could see what happens when the 

 little drop of what — for lack of a better name — we shall 

 call honey-dew is exposed, you would begin to guess the 

 reason. Wherever these larvae are found you will also 

 find many ants wandering round among them, and the 

 moment the honey -dew appears these ants begin to sip it 

 up. When it is all gone the little caterpillar draws in its 

 pocket again and presumably begins to store up another 

 bit of liquid. It is certainly a curious example of what the 

 naturalists call symbiosis, which simply means a living to- 

 gether of two animals, each helping the other in some way. 

 In this case it is easy enough to see how the caterpillar 

 helps the ant, but perhaps you are wondering in what pos- 

 sible way the ant may help the caterpillar. I hardly dare 

 give the most plausible explanation for fear some one will 

 cry out, "Nature-faker!" But fortunately the explana- 

 tion is based upon at least one precise observation by W. 

 H. Edwards, one of the most careful and reliable natural- 

 ists America has produced, who lived before the recent era 

 of Nature-fakers and was never accused of sensationalism. 

 Mr. Edwards saw an ant drive away from one of these 

 caterpillars a little parasitic fly which apparently was 

 searching for a victim. Consequently, it would appear 

 that the ants helped the caterpillars by protecting them 

 from these arch enemies. 



This is by no means an isolated example of the relations 

 between ants and other insects. It has been known for 

 hundreds of years that the ants use the aphids as a sort of 

 domestic milk-producer, attending the aphids at all times 

 and even caring for their eggs throughout the winter 

 season. As the plant-lice live in colonies, sucking the sap 

 of their host plant, they are attended by great numbers of 



