FIGHTING THE INSECTS 



Careful studies by later students of plant-lice have turned up 

 many life histories as interesting as this, showing a relation be- 

 tween annual and perennial plants as to their plant-louse popula- 

 tions. 



While this study showed a comparatively easy method of 

 control, I think that perhaps it was this close and accurate in- 

 vestigation of plant-louse methods of life (although already 

 known in a general way) that really started me thinking about 

 insect possibilities. And I was hardly astonished when Professor 

 Glen W. Herrick brought out his extraordinary calculation that 

 the ponderable mass of the offspring of a single cabbage aphis 

 in five months' time in Central New York would, without acci- 

 dent or control, exceed the ponderable mass of all humanity on 

 the globe by at least five times. 



[74] 



