SUPERFAMILY GELECHOIDEA 



169 



The larvae are leaf-miners, and the mines are easily distin- 

 guished from most others by the scrupulous cleanliness with which 

 the larva ejects all its frass through a hole, so that the mine re- 

 mains clear and white. At maturity the larva changes its color 

 from green to a vivid purple or wine-red, leaves the mine, and 

 spins a matted flattened cocoon of silk. 



The larvae, as far as known, seem to prefer herbaceous 

 plants — principally vines and grasses. 



The rich-weed leaf-miner, C. pulchrimella, infests the 

 leaves of Pilea pumila, "mining, twisting and crumpling 



Fig. 51. A leaf of enchanter's nightshade bearing a mine of Cosmopteryx. 



them." The larvae may leave the mine and wander about 

 over stems and leaves "cutting in between the two cuticles 

 of a leaf, and covering it with transparent spots of various 

 sizes." 1 Pupation is outside the mine in a fold of the leaf 

 or on the ground "protected by a very slight dingy cocoon." 

 The work of a panic grass leaf-miner, C. gemmiferella, is 

 described by Miss Braun (1923) as follows: 



The larva mines the small basal leaves of Panicum dichotomum 

 Linnaeus, in the spring, eating out almost the entire substance of 

 the leaf. Just before pupation, it enters one of the lower stem 

 leaves, in which it makes a small inconspicuous mine, scarcely 



1 From Miss Murtfeldt, as quoted by Busck (1906). 



