274 NEW YORK STATE MUSEUM 



The fore luetatai'siis about one fourth shorter tliau its tibia, and 

 about oue third longer than the next tarsal joint; tarsi bare. 

 Length 2.5 to 3 mm. 



Female. Diflers from the male thus: The base of the antenna 

 is often yellow, the thoracic stripes are always distinct, the yellow 

 of the dorsum is usually conspicuous; the abdomen is stouter, less 

 hairy, venter very often consi)icuously yellow; the wings cinereous, 

 the wing veins near the costal margin subtestaceous, and lastly, 

 the body is stouter. Length 2 to 2.7 mm. 



8. Orthocladius nivoriundus Fitch 

 1846 G li i r o u o m u s Fitcli. Wiuter iusects of Eastern New York. p. 274 

 1878 Chironomus Osten Sacken. Cat'l. Dipt'. N. A. p.21 

 1898 O 1- 1 h o c 1 a d i u s Johnson. Cat'l. N. J. Dipt, p.627 



I formerly erroneously regarded this species as a synonym of 

 D i a m e s a waltlii. 



Larva. (P1.24, figs.18 to 24). The larvae were collected from 

 pond water on March 28 and the tiies emerged the following week. 

 The larva is a pale green creature, somewhat infuscated on the 

 dorsum. Length G mm. Head deep brown, short; antennae 

 (fig.ll)) short, a little less than three fourths as long as the mandi- 

 ble, first joint three fifths of total length, apical appendage of the 

 first joint as long as the second and third joints taken together. 

 Each eye consists of a pair of spots separated by a tine line. 

 Labrum with three pairs of moderate size and about three pairs 

 of small setae on the lower surface; epipharynx with the usual 

 arms and curved pectinate setae. The mandible is stout, with 

 black toothed apex; the maxilla (fig.21 mx) has a small palpus, 

 several jjlunt setae, some fine hairs and a bunch of mesad pro- 

 jecting, delicate, pointed filaments. The free margin of the labium 

 is provided with black teeth, the middle one broad, with a rounded 

 margin (fig.21 1). The dark thoracic prolegs have the usual 

 slender hairs, but these are apparently either bifid or pectinate. 

 The anal prolegs have sharp bilobed claws. The papillae of the 

 anal hair tufts are short and dark brown in color. Caudad of 

 these is a pair of prominent setae and on the ventral surface 

 cephalad of the anal prolegs is another pair. The anal prolegs 

 are of the usual form. The anal blood gills are present. 



Pupa. Black or deep fuscous; abdomen paler. length about 

 4 mm. The thoracic spiracles are slender, tubular, with a rough- 

 ened surface (fig.28) ; length perhaps a little less than an ab- 

 dominal segment. The dorsum of each segment, excepting the 

 seventh and eighth, is nearly wholly covered with very short, 

 microscoi)ic spines, l)esides about four pairs of longer black setae 

 as shown in fig. 22. Sometimes those near the caudal margin 



