192 PAPERS BY DR. B. CLEMENS. 



NEPTICULA MINERS OF THE SYCAMORE LEAF. 



I ascertained during the fall of 1861, that there is more 

 than one species of Nepticula that mines the leaves of the 

 sycamore tree, and that all of them are double-brooded. The 

 first brood may be taken early in June and July, and the 

 second during the latter part of September and early in 

 October. 



The mine and larva of one species is described in the 

 November and December number of the present work for 

 1861, page 83,* and the imago in the January and February 

 number for 1862, page 133 ;f but it may be well to repeat 

 here, for the purpose of comparison, a more circumstantial 

 description of the mine of the species to which allusion is 

 made. 



The mine of Nepticula Platanella begins as a very slender 

 track, the entire length of which is filled with fr ass. This is 

 very soon expanded into a round, conspicuous, blister-like 

 blotch, on the upper surface of the leaves, which sometimes 

 obliterates the early portion of the mine ; but in this event it 

 is still perceptible on the separated epidermis as a slender, 

 dark-brown line. After the blotch has been formed, the 

 "frass" is diffused over the floor of the mine, discolouring its 

 surface. 



Sycamore miner. No. 2, mines in quite a straight line, 

 when its course is along a vein of the leaf, otherwise it is 

 slightly winding. The mine begins as an extremely minute 

 tract, and is gradually enlarged towards the extremity. A 

 day or two before leaving its mine the larva enlarges the end 

 into a small blotch) which has attached to it a long linear 

 track, with a central line of blackish frass. In the enlarged 

 portion of the mine the frass-line changes into one of scattered 

 and separated grains. 



The larva is of a lively or bright-green colour, with a dark- 

 green central line of intestinal matters. Head pale brownish. 



* See ante, p. 173. H. T. S. 

 f See ante, p. 183. H. T. S. 



