576 William T. M. Forbes 



Larvce 

 1. With tracheal gills. 



2. Anterior and posterior infrastigmatal gills with the same number of fila- 



- ments (five when full-grown) 5. maculalis. 



2. Posterior subdorsal and infrastigmatal and pedal gills with the same 

 number of filaments; anterior infrastigmatal with one less. 

 3. Maximum number of filaments in last stage six; usually feeding on 



Vallisneria 7. obscuralis. 



3. Maximum number of filaments four; usually feeding on Limnanthemum. 



6. seminealis. 

 1. Xo tracheal gills; second abdominal spiracle decidedly smaller than third; 

 caterpillar stout and flattened, with head darker than body. 

 2. Head dark chitin-yellow ; case nearly circular. 



3. Body whitish; thoracic tubercles more distinct than abdominal ones; 



head with a lateral brown stripe; on Potamogeton 3. obliteralis. 



3. Body pale yellow; tubercles all similar; head with dark spot confined to 



mouth parts ; on Nuphar 4. gyralis ( ? ) . 



2. Head dark brown, body dirty gray; in an oblong case on Potamogeton and 



probably Menyanthes 2. icciusalis. 



2. Head not noted; larva on sedge 1. ekthlipsis. 



I. Larva without tracheal gills, breathing air; the case full of air; pupa 

 with first open spiracle smaller than the other two; moth with fore wing 

 typically subfalcate; Sc sepai-ating from R halfway between cell and apex, 

 the free part at least two-thirds as long as free part of R; palpi normally 

 hairy below; antemedial line of hind wing crossing cell perpendicularly 

 ( Hydrocampa, Nymphula ) . 



1. N. ekthlipsis Grote. Maxillary palpi smaller than in the other species; half 

 as large as third segment of labials; fore wing subfalcate. White, with three 

 confused bands on basal half, the outer one angled out on Cu, and touching the 

 lower end of the large kidney-shaped reniform; postmedial band yellow, its inner 

 margin running in a curve from costa to lower outer angle of reniform, and in a 

 shorter curve from inner angle of reniform to inner margin, with the lower part of 

 the antemedial band enclosing a circular white spot. Subterminal band white; all 

 the markings heavily edged with brown, sometimes largely covering the yellow; 

 subterminal line brown, closely parallel to margin, followed by a light brown 

 and yellow stripe and white fringe. Hind wing similar, the basal marks replaced 

 by a straight antemedial band, edged outwardly with dark brown. 18-25 mm. 



Larva in an oblong case on sedge. 



General but local, south to New York and Illinois. New York: Ithaca, Mich- 

 igan Swamp (Tompkins County), Albany. 



2. N. icciusalis Walker. Yellow or brown, shaded with silvery white; base with 

 considerable white; a white triangle at middle of costa with a black bar on its 

 front edge; a white discal crescent, edged outwardly with black; a white circle in 

 middle of fold, strongly outlined with black, and variable in size; subterminal 

 line strongly irregular, sometimes edged outwardly with black, at least toward 

 apex; fringe barred, brown and white. A fine white postmedial line following 

 the outer edge of the reniform lunule and the circle on the fold. Hind wing 

 similar; antemedial band as in N. ekthlipsis, postmedial line irregular, edged 

 before, and sometimes beyond, with black; discal spot large, yellow; subterminal 

 line as on fore wing. Ground of basal two-thirds white, of outer third, yellow 

 or brown. Ground rarely both yellow and brown, the region beyond the cell, 

 and the base of the fore wing being contrastingly light; white and black mark- 

 ings of the fore wing sometimes suffused. 12-20 mm. {formosalis Clemens, 

 genuialis Lederer.) 



