18()1.] 81 



to indicate the presence of a mine. 



Usually the species are confined to a single plant; some, however, feed 

 on several allied plants. 



The larva never quits the mine and changes in it to a pupa. Some 

 species makes no cocoon, others only a very slight one and others make 

 one of grains of excrement woven together with silk. 



Many of the species of the fall brood remain in the pupa state during 

 the winter and appear as imagos in the spring, and some of the imagos 

 that appear late in the fall seem to hybernate during the winter in the ima- 

 go state. The spring brood of larva3 produce imagos in the summer. 



When the imagos escape from the mine the pupa case is thrust through 

 the separated cuticle, and left there after the escape of the imago. 



1. L. Salicifoliella. During the latter part of June or early in 

 July the leaves of yellow willow Sallx vltclHua^ var. .S'. aU>a, should be 

 searched for this insect. The mine is on the under surface usually near 

 the base of the leaf and along the edge. I found these mines for the first 

 time on the 2ord of July of the present year, but they were untenanted and 

 the imagos had escaped, so that I am unable to furnish any further partic- 

 ulars respecting the species. 



2. L. Juglandiella. The larva makes an elongated, rather wide 

 tract on the upper surface of the leaves of black walnut, without folding 

 the leaf, and may be found from the beginning to the middle of the month. 



It is blackish or blackish-brown, with a few pale brownish dots on each 

 side of the thoracic segments, and with the tip of the abdomen and head 

 pale brown, It belongs to the second larval group described in the Pro- 

 ceedings of the Academy of Natural Sciences of Philadelphia November 

 1859 and may not be specifically distinct from L. C(n-t/fefoUdla described 

 on page 328. 



ASPIDISCA. 



HABITS OF THE LARV^. 



The larva3 of this genus are characterized by making a small blotch 

 mine between the cuticles of the leaves and when they have arrived at 

 maturity weaving a cocoon between the cuticles, and cutting out of them 

 a small, oval disk, thus leaving a hole in the mined place of the size and 

 shape of the cocoon. In this respect they resemble the genus AnfiApila. 



The larvae of the two geiici-a are, however, easily distinguished by their 



