525 



6. Orthocladius nigritus, n. sp. 



Differs from the foregoing in having the basal joint of the fore 

 tarsi four fifths as long as the fore til)ise, the hypopygium as in Figure 

 3, Plate XXXX'II, and the halteres brown or black. In other respects 

 very similar to both obuuibratus and nivoriiindus. 



Length, 2.5-3 ™"''- 



Type locality, Cabin John, Md., Feb. 16, 1913 (\V. D. Appel). 



Type in collection of U. S. Bureau of Biological Survey. Para- 

 types in collection of Illinois State Laboratory of Natural History. 



7. Orthocladius xivoriuxdus Fitch 



Chironomus nivorkmdus Fitch, Winter Insects of Eastern New York, p. 274. 1846. 

 Orthocladius nivoriundus (Fitch) Johannsen, Bull. 86, X. Y. State Mus., 1905, 

 p. 274. 



Larva. — Length, 8-9 mm. Brownish yellow. Antennae of mod- 

 erate length, not over one third as long as head, basal joint about five 

 times as long as its diameter, second joint about one fifth as long as 

 basal and subequal to remaining joints taken together; eye spots indis- 

 tinguishable in cast skin ; labium as in Figure 16, Plate XXIX ; mandi- 

 bles each with three distinct teeth; anal tufts each consisting of about 

 twelve hairs, basal papillse about twice as long as their diameter; dor- 

 sal blood-gills well developed ; anterior pseudopods with many soft, 

 dark apical hairs and numerous short preapical setulae ; posterior pseu- 

 dopods with the apical hairs clawlike. 



Pupa. — Length, 6-7 mm. Brown. Thoracic respiratory organs 

 as in Figure i, Plate XXX\'III; abdominal segments 2-6 with the 

 disc, except the lateral and extreme anterior margins, covered with 

 very small setulae (Fig. 9), those on the sixth segment being in groups 

 of two to four, and those on the other segments occurring singly ; seg- 

 ments 2-^ each with four brownish spots, one near each antero-lateral 

 angle and one on each side of the median line about one third from 

 the posterior margin ; second segment without posterior transverse 

 row of strong setulae ; eighth segment as in Figure 5, Plate XXXVIII ; 

 apical abdominal appendages with moderately long lateral fringe and 

 three long apical hairs (Fig. 3). 



Imago; Male. — Agrees in color with nigritus, differing principally 

 in the comparative lengths of the basal joint of the fore tarsi and fore 

 tibiae and in the structure of the hypopygium (PI. XXXV^II, Fig. 12). 



Length, 3-4 mm. 



Illinois localities : Illinois River at Havana ; Homer and St. 

 Joseph; Dubois and Parker. 



