148 



INSECT MANUFACTURES. 



insect alights on the leaf, pierces it with a very 

 sharp instrument with which she is provided for 

 this purpose, and deposits an egg so minute as to 

 be almost invisible to the human eye. The punc- 

 ture of this insect produces a diseased action in 



LEAF GALLS. 



the leaf, so that the parts immediately surround- 

 ing the egg swell and harden until the apple- 

 shaped body is produced. This is now an admi- 

 rable place of shelter, and a reservoir of food for 

 the insect within, which remains snugly encased 

 until it arrives at its perfect state, when it cuts 

 its way out through the solid substance of the 



