186 ELEMENTARY STUDIES IN INSECT LIFE 



ants, have become dependent upon the ants. This 

 illustrates the effects of use and disuse. Undoubtedly 



/ 



the aphids were once independent and self-supporting 



FIG. 153. Newly hatched scale insect. Greatly enlarged. 



and unattended by ants. Had the ants never under- 

 taken the care of these aphids in the first place, the 



aphids would still 

 be in full possession 

 of all their powers 

 and instincts ; but 

 the ants having 

 through many gen- 



FIG. 154. Protective covering of female scales p 



(Aspidiotus greenii). CratlOUS aSSUmed tllC 



care-taking responsibility, this faculty or instinct of the 

 aphids, not being used, has evidently been lost. Ants 

 running up and down trees are not infrequently going to 

 and from these aphid pastures. Among the plant-lice 



