MAY FLIES AND MIDGES OF NEW YORK 255 



Length 3 to 4 mm. Schiner, loc. cit. (trieinctus) . North Amer- 

 ica (O. 8.) ; Ithaca N. Y.; Chicago 111. 



"The variety with less black, the thoracic stripes narrower, and 

 the femora only black at the tip, is known as var. t r i f a s c i a - 

 tus". V.d.Wulp (1877). 



4. Cricotopus exilis n. sp. 

 (P1.24, figs. 1-4; pl.29, fig.16; pl.33, fig.2) 



Larva. The yellowish green larvae were taken from the rocky 

 bottom of the shallow but swift, Fall creek water at Ithaca N. Y. 

 Length, 4 to 5 mm. In most of its details the larva is like that 

 shown on pl.25, figs. 12 to 15 ; but I fail to find a seta on each side 

 at the base of the labium. The lateral surface of the mandible 

 is wrinkled (fig.4), and the curved setae of the epipharynx are 

 more prominent (fig.2) ; neither are the oblique wrinkles below 

 the teeth of the labium present. Claws of anterior prolegs are 

 coarse and pectinate. 



Pupa. The pupa is yellowish with black; the colors of the 

 adult showing through the integument. Length about 2 mm. 

 The markings of the abdominal segments resemble those shown 

 on pl.25, fig.7. The caudal appendages consist of the genital sacks 

 and the three setae at the end of each lateral process of the anal 

 segment. 



Imago, female. Head, occiput and upper half of front blackish, 

 the narrow horizontal space above the antennae and face bright 

 yellow; palpi brownish; probocis yellow; antennae brown, the 

 two basal joints yellowish, antenna! hairs whitish with an 

 occasional black one. Thorax dusky yellow with three wide 

 shining black stripes, the median one much abbreviated behind, 

 and very narrowly divided posteriorly by a yellow stripe, lateral 

 stripes much abbreviated in front. Pleura yellow with 4 brown- 

 ish spots or bars at base of wings; pectus yellowish brown; 

 scutellum and metanotum black, the latter with a very narrow 

 yellow median line. Abdomen black and yellow, its dorsum with 

 yellow markings as follows : First segment, narrow basal margin 

 of second, very narrow apical margin of third, all of the fourth 

 and fifth except brownish clouds among the marginal setae, sixth, 

 seventh and eighth faintly at base and apex, and all of anal seg- 

 ment; thus leaving most of the second, third, sixth, seventh and 

 eighth blackish. Genitalia white. Sides of abdomen and venter 

 sordidly yellow, darkened apically. Near the posterior margin of 

 each segment there is a row of black setae, excepting on the first 

 segment, where they are paler colored. Coxae yellowish. The 

 basal one fourth of the fore and basal one half of middle and hind 



