Fig. 58. Seedling mountain ash photographed June 25, 1913 to show 

 colony of woolly aphids which are the progeny of migrants from elm 

 leaf rosette caged with mountain ash, June 17, 1913. Two apterous 

 generations matured on this seedling, but the third generation proved 

 too much for the little tree which was so nearly dead by August 10 

 that the last of the aphid colony perished at that time. 



