LEPIDOPTERA 



599 



Fig. 724. — -Leaf infested by the 

 maple-leaf cutter. 



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. 



Subfamily Prodoxin^. — This 

 subfamily includes the remarkable 

 insects that are known as the yucca- 

 moths and the closely allied bogus 

 5rucca-moths. 



The yucca-moths, Tegettcula. — Four species of this genus are now 

 recognized; the best-known of these is Tegettcula alba. The life- 

 history of this species was first described by Mr. C. V. Riley ('73), 

 under the name Pronuba yuccasella; and in most of the accounts of 

 this insect this name is used. The moth, however, was first de- 

 scribed as Tegeticula alba. The most complete account of this and 

 the allied species is that of Riley ('92). 



This species infests Yucca filamentosa, a plant not fitted for self- 

 pollination or for pollination by insects in the ordinary ways; in 

 fact, it is poUinized 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. 725, b), fitted for 

 the collection of pollen. After collecting a large load of pollen, often 

 thrice as large as the head (Fig. 725,), the female moth places her 

 eggs, by means of her long, extensile ovipositor, into an ovary, usually 

 of another flower than that from which the pollen was collected. 

 After oviposition, the moth runs up to the tip of the pistil and thrusts 

 the pollen into the stigmatic opening. Thus is insured the develop- 

 ment of seeds, upon which the larv^ hatched from the eggs placed 

 in the ovary are to feed. As many more seeds are developed than are 

 needed by the larvae, the perpetuation of the yuccas is assured. 



