THE CANADIAN ENTOMOLOGIST. 55 



either hollow or not. according to the species. These markings change at 

 the mountings sometimes, but I have never found any variation in the 

 markings of the full-grown larvae of a species among themselves, though 

 sometimes they differ in larvae from different species of plants which yet 

 produce the identical imago. The mines, likewise, of the same species, 

 do not vary essentially upon the same plant, nor usually upon different 

 plants ; yet sometimes different mines upon different kinds of leaves pro- 

 duce the same imago. Examples of these variations will be given further 

 on. Usually, the larva of a species is confined to a single species of 

 plants, or if it mines the leaves of more than one species they are generally 

 closely allied ones ; but sometimes it happens that the same larva — or 

 one producing the same imago — mines the leaves of widely different 

 plants. 



It frequently happens that the same plant or even the same leaf is 

 mined by more than one species of larva, and I have seen upon the same 

 locust leaf ( ' Robinia pseudacacia) the mine of Lithocolletis /tobinietla, Clem. . 

 Pareetopa Robiniella, Clem., and another mine, which is, perhaps, that of 

 Anacampsis Robiniella, Fitch, though I have not bred the imago ; and there 

 is still another miner (of the upper surface) which makes a white, tent-like 

 mine, but with the imago of which I am not acquainted as yet. 



Usually a mine is tenanted by only a single larva, but as the mines 

 spread they frequently unite. There are, however, among the larvae of the 

 2nd group, some which occasionally, and others which almost invariably, 

 have several larvae even in the very young mine, and I have seen fifteen 

 larvae in a mine scarcelv a line in diameter. 



With very few exceptions, the pupa state is passed in the mine, the 

 exuvia being left partly within and partly without the mine by the emer- 

 gent imago. A few instances only are recorded in which the larva leaves 

 the mine to become a pupa : and Dr. Clemens has recorded a single in- 

 stance, that of L. erataegella, in which the larva sometimes leaves an old 

 mine and forms a new one. 



SECTION A. 



SPECIES WITH THE GROUND COLOR WHITE. 



Div. ist.- — Some portion of the wings of some shade of yellow. 

 Sub-div. a. No apical spot — no basal streak. 

 * Wings marked with fasciae. 

 i.—L. hamadryadella, Clem., Proe. Aead. Nat. 'Set., Phila. 1859. 

 There is considerable variation in the distinctness and disposition of 



