256 



THE STUD Y OF INSECTS. 



curious type of larval habits. It infests the leaves of maple, 

 and occasionally is so abundant that it does serious injury. 

 The leaves of an infested tree present a strange appearance 

 (Fig. 303). They are perforated with numerous elliptical holes, 



and marked by many more or 

 less perfect ring-like patches 

 in which the green substance 

 of the leaf has been destroyed, 

 but each of which incloses an 

 uninjured spot. These inju- 

 ries are produced as follows: 

 The young larva cuts an oval 

 piece out of a leaf, places it 

 over its back, and fastens it 

 down with silk around the 

 edges. This serves as a house 

 beneath which it lives. As it 

 grows this house becomes too 

 small for it. It then cuts out 

 a larger piece which it fastens 

 to the outer edges of the 

 Fig. 303.— Leaf infested by incurvaria. smaller one, the larva being 

 between the two. Then it fastens one edge of this case to 

 the leaf by a silken hinge so that it will not fall to the 

 ground " cradle and all," and then turns the case over so that 

 the larger piece is over its back. When it wishes to change 

 its location it thrusts out its head and fore legs from the 

 case and walks off, looking like a tiny turtle. When it 

 wishes to eat it fastens the case to the leaf and, thrusting its 

 head out, eats the fleshy part of the leaf as far as it can reach. 

 This explains the circular form of the patches, the round 

 spot in the center indicating the position of the case. The 

 insect passes the winter in the pupa state within its case ? 

 which falls to the ground with the infested leaf. The moth 

 is of a brilliant steel-blue or bluish-green color without spots; 

 it appears in early summer. 



