INSECT HERDS AND HERDERS 



raised abdomen. Do you the same, and you shall see 

 a minute drop of transparent liquid exuding. You 

 have barely noticed it ere it has disappeared within the 

 ant's gullet! After a few moments' waiting, again a 

 droplet forms, which is also quickly lapped by the 

 attendant ant. 



A longer interval must elapse ere another globule 

 shall form, and you will grow impatient. The ant will 

 hasten matters for you. See! She is gently stroking 

 with her antenna) the back of the aphid. Now on one 

 side, now on the other, the delicate organs are gently 

 drawn again and again. What does this mean? Why 

 does your cat purr and curl contentedly in your lap when 

 you stroke her fur? Why does your dog bend his head 

 and stand still with such a seeming of muscular relaxa- 

 tion and physical content when you stroke his head? 

 Or, to get nearer home, why does the male of the human 

 species (and some of the females as well) yield his head 

 with such unutterable satisfaction to the deft manipula- 

 tion of a loved hand, with or without the comb? Can 

 you tell why? Then you know why the ant strokes 

 the aphidian back, which is covered with papillae or 

 minute hairs. She has learned from her own experience 

 " how good it feels," and is promoting the aphidian com- 

 placency by an approved method. 



And now another droplet of the sweet liquid is form- 

 ing, yielded by the aphid to the deft diplomacy of the 

 emmet. That liquid is the entomologist's "honey- 

 dew," and you have seen an ant milking her cows! All 

 over the tree, like scenes are occurring between hosts of 

 foraging ants and aphids. 



The ant laps honeydew from the aphid; the aphid 

 pumps sap from the tree; the tree draws moisture from 



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