242 THE LIFE OF AN INSECT. 



the water, but whose pupa is an air-breathing 

 creature, and consequently would perish if the 

 change from larva to pupa were to take place 

 under water, without some especial contrivance 

 to furnish it in the pupa form with a supply of air. 

 Yet how can this be, when the insect is under 

 water the whole time up to its becoming a perfect 

 moth ? We shall hear : 



" At the commencement of spring, as soon as 

 the frost and ice had disappeared, I sauntered out 

 one day to procure some fresh plants from the 

 bottom of a stream, in order to feed some of my 

 caterpillars with them, Between the leaves of 

 these aquatic plants I presently found a large 

 number of aquatic larvae, which had there safely 

 passed through the rigorous season just gone by. 

 I took a number of them, and put them in some 

 boxes, where they eat the leaves with which I fed 

 them. There they grew larger from day to day, 

 although by slow degrees. I tended them until 

 June in the same year without perceiving any 

 other change in their appearance than that they 

 had grown to a considerable size. But at the 

 commencement of this month I noticed that tjiey 

 became very uneasy ; they forsook their leaves, 



