AS BOTANISTS 53 



furnished it by Mr. Mead whereon to lay her 

 eggs, and no one has yet reared it upon anything 

 but Aster novae-angliae. Considering the diffi- 

 culty that botanists have with the species of this 

 group, such restriction of choice, if really true, 

 certainly indicates some keen perception on the 

 part of the butterfly. 



Now with exceedingly rare exceptions the eggs 

 of butterflies are laid upon the very plant upon 

 which the caterpillar will feed. In certain in- 

 stances where the plants are abundant, as in the 

 case of grasses, the butterfly may lay upon an 

 object in the near vicinity, and tliis has also 

 happened in a few instances in the case of butter- 

 flies which are rather particular in their choice. 

 Thus I once saw a European Satyrid lay an egg 

 on a dead blade of grass lying loose upon the 

 ground, have seen one of our species of Brenthis 

 lay eggs upon grass in the vicinity of violets, and 

 found the egg of a Pamphilid upon a thistle grow- 

 ing among grasses. These exceptions seem only 

 to prove the general rule that the eggs of butter- 

 flies are laid directly upon the food plant of the 

 young. 



This is an act of instinct, one will say. But is 

 this any real explanation? We wish to know how 



