LEPIDOPTERA 



i95 



Leaf infested by the maple-leaf 



Family Incurvariid^e 



An interesting representative of the family Incurvariidae is the maple- 

 leaf cutter, Paraclemcnsia acerijoliella. The larva infests the leaves of 

 maple, and occasionally is so abundant 

 that it does serious injury. The larva is at 

 first a leaf-miner, but later it is a case-bearer. 

 The leaves of an infested tree present a 

 strange appearance (Fig. 335). They are 

 perforated with numerous elliptical holes, 

 and marked by many, more or less perfect, 

 ring-like patches in which the green sub- 

 stance of the leaf has been destroyed but 

 each of which incloses an uninjured spot. 

 These injuries are produced as follows: 

 the larva, after living for a time as a leaf- 

 miner, 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 smaller 

 one, the larva being between the two. 

 Then it crawls halfway out upon the leaf, and by a dexterous lifting of the 

 rear end of its body 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 but 

 with an orange-colored head; 

 it appears in early summer. 



The yucca moth, Tegeticula 

 alba, is another interesting 

 member of this family. This 

 species infests Yucca filamen- 

 tosa, a plant not fitted for self- 

 pollination or for pollination by 

 insects in the ordinary ways ; in 

 fact, it is pollinized only by 

 moths of the genus Tegeticula, 

 the larvae of which feed on its 

 seeds. This is one of the few 

 cases in which a particular plant 

 and a particular insect are so 

 specialized that each is dependent upon the other for the perpetuation of the 

 species. In the female moth, the maxillae are each furnished with a long, 

 curled, and spinose appendage, the maxillary tentacle (Fig. 336), fitted for the 



Fig. 336. — Tezeticula alba: a, side view of head and neck 

 of fern ile denuded; i, load of pollen; 2, maxillary tentacle; 

 .?, maxillae; 4, maxillary palpi; 5, antennae; b, maxillary ten- 

 tacle and palpus. All enlarged. (From Riley.) 



