LEPIDOPTERA OF NEW YORK AND NEIGHBORING STATES 195 



All of the species are miners on the upper side of leaves, where they make a 

 flat, sometimes irregularly shaped blotch, or a rather broad, linear tract. The 

 larva feeds from the centre outwardly, thus gradually increasing the extent of 

 the mined portion of the leaf. The mine retains its flat, blotch-like character 

 until after the seventh moult. The larva then lines the loosened epidermis with 

 silk and by contraction produces from one to three narrow folds or ridges. Beneath 

 this folded portion, the floor of the mine is thinly covered with silk. Then the 

 larva, lying on its back, spins a flat, semi-transparent sheet of silk, oval or nearly 

 circular in shape, and attached around its edges to the floor of the mine. Beneath 

 this, along its long axis, the pupa is formed. The pupa, which is protruded from 

 the mine in emergence, is thrust through a transverse slit near one end of the flat 

 cocoon. Such a cocoon is formed in all but a few of the species of which the life 

 history is known. 



In almost all of the species, however, this cocoon is only made in the brood of 

 which the imagoes are to appear in the same summer. In a later brood, the 

 hibernating period, with one or two exceptions, is passed in the larval state. In 

 a number of species, hibernation takes place beneath the folded epidermis. In most 

 cases, however, an especially prepared, silken-lined chamber is formed. After the 

 floor of the mine is loosely covered with silk, the upper epidermis is fastened down 

 in a circular or oval outline, and the whole cavity is then lined with silk. Ample 

 space is provided by a characteristic oval, or hemispherical, projection upon the 

 under side of the leaf. The change to pupa occurs in the spring. Except for the 

 absence of cremaster, the pupa is identical with that of the cylindrical-larval group. 



The moths of this group may easily be recognized by the fact that the white 

 markings of the fore wings are always externally dark-margined, and often densely 

 dusted with black scales behind. In some cases there is, in addition, a slight 

 internal margin, consisting of a few dark scales near the costa. The markings 

 consist of white costal and dorsal streaks, usually oblique. Opposite streaks may 

 unite to form a fascia, either outwardly angulated or straight. 



Key to the species 



A. Oblique costal and dorsal streaks; fasciae, if present, distinctly angulated; 

 never two straight fasciae. 



B. Ground color of the fore wings white 48. hamadryadella. 



BB. Ground color of the fore wings not white. 



C. An oblique white streak or patch at the base of the dorsal margin, rarely 



indistinct (lentella, caryaefoliella) usually two, angulated fasciae. 

 D. No costal streak before the middle; a median fascia.. 51. saccharella. 

 DD. A fascia at one-fourth and one at one-half. 



E. White streak at base of dorsum indistinct, or indicated by external, 



dark scales only. 

 F. Third costal streak long and usually uniting with the third 



dorsal 52. caryaefoliella. 



FF. Third costal streak merely a spot 53. lentella. 



EE. White streak at base of dorsum large and distinct. 



F. A tuft of brown scales in the apical cilia 50. macrocarpella. 



FF. No such tuft of scales 49. cincinnatiella. 



CC. No such pale streak at base of dorsum. 

 D. Dorsal margin white from base to beyond middle. 



E. Dorso-basal streak extending to oblique streak above the cilia. 

 F. Antennas annulate with brown for their whole length. 



54. conglomeratella. 



FF. Basal third of antennae pure white 55. ulmella. 



EE. Dorso-basal streak extending but little beyond the middle of the 

 dorsal margin 56. quercivorella. 



