IsCl.] 83 



the .separated eutielo. in itrtler tu weave a minute cocoon. 



The larvae of some dipterous insects make mines that strongly resemble 

 those of some of the iVcpticidse, but they may usually be distinguished by 

 the more maggot-like appearance of the former. 



1. N. Corylifoliella. The larva makes a long, winding, narrow 

 tract in the leaves of Hazel in the latter part of July and the beginning 

 of August and the foil brood may be found early in October. The /ra.s.s 

 or excrcTuent of the larva is deposited along the middle of the tract, form- 

 ing a minute central black line. The edges oi the mine are smooth, and 

 but little broader throughout its extent than the width of the miner. 



The mine is left transparent by the larva from the beginning to the end. 



There is another miner in this leaf that I suspect to be a dipteron. It 

 makes a rather broad, tortuous tract, much broader than the preceding, and 

 the '• frass " is scattered in separated grains along the middle of the tract. 



2. N. OstryEefoliella . The larva in July and August makes a rath- 

 er wide, most frequently much contorted, transparent mine, with a ncn-roic, 

 central, Hack line of ''/rass'' ; sometimes the early portion of the mine is 

 filled up with '• frass " and in others the line of frass is distinct from the 

 beginning. From the middle to the end of the mine whence the larva es- 

 capes it will average nearly a line in width. 



8. N. Virginiella. In the leaf of Iron-wood, Osfr//a; makes a very 

 narrow, long tract, not broader than the width of the larva, the interior of 

 which is filled up irifh dispersed t/rains of frass, and which is dark brown 

 whilst the larva is mining. The larva is very slender, of nearly uniform 

 diameter, terminal segments pointed, pale green, with a darker green cen- 

 tral line, head pale brown. It should be sought early in September. 



On the 14th of the month it is nearly full fed. 



4. N. Platauella. From the begiuuiug to the middle of July the 

 blotches produced by these larvae may be found on the leaves of the But- 

 ton-wood tree or Sycamore. The blotch is often extended over the early 

 portion of the mine so as to obliterate it and again the early portion is pres- 

 ent, being a slender line from which the blotch is formed. 



The larva is pale green and the head pale brown and weaves a cocoon 

 of a reddish-brown color during the latter days of July. 



5. N. Crataegifoliella. The larva may be found in the leaves of 

 Dwarf Thorn, Cratsejus parvifolia, from the middle to the latter part of 

 July. The mine is rather a wide tract, not long, most often tortuous, 

 sometimes turned back on itself and when nearly straight, with irregular 

 edges, having a narrow, contorted line of frass running through the mid- 



