280 Winter Insects of Eastern Mno York. [May, 



reachinjr ])ut half the length of the wings; sutures of the tergum 

 in tlie female more or less widely marked with dull rufous; tip, in 

 the female only, furnished with two short, fdiforrn setje, scarcely 

 e(|ualling in length tin; segment to whieh tlu^y are attached; sctte 

 pale lurid, sub-diaphanous, hairy, composed of about eight joints. 

 Kach segment ol the venter with two transverse impressions, one 

 situated towards each posterior angle. Male organ exserted, 

 forming a conical lurirl ])()int near the base of the last ventral 

 segment. Femurs cylindrical, black, clothed with white hairs, 

 which are longer and more distinct in the females, inner side with 

 a narrow deep groove which is dihited towards the apex. Tibice 

 cylindrical, about half the diameter ol the femurs, grooved, lurid- 

 brown, dia)>han()us, the ends and inner sides black; apex slightly 

 incurved and armed wiih two short S[)itu\s on the inside. 7am 

 black, composed of three joints, whereol" the middle one is slight- 

 ly shorter; two claws and an intervening pellet at the tips. 

 Wings griseous, when closed showing faintly two paler bands, 

 one near the middle and the other ])ack of it; edges ciliated with 

 fme, short hairs. Up|)er wings diaphanous, grey, i'aintly niaiked 

 with a darker cloud hack of the middle, and another occupying 

 the tips, hut not reaching to the edge, these clouds becoming 

 wholly obliterated in cabinet sjx-cimens; nervures black. Lower 

 wings grey, sub-hyaliue, nerv\ui'S black. 



When recently excluded from the pupa, the ab'domen, except 

 at its tip, is ol'a didl rufous color; this gradually becomes darker, 

 and finally pure black. For a time after the venter has be(;ome 

 wholly black the tergum continues dull rufous with a black band 

 on each segment, whicli band does not reach the lateral margins. 

 These bands increase in size, and at length tlu; whole teigum is 

 overspread with j)ure black. 



]t is not uncommon to meet with specimens of this and the pre- 

 ceding sp(!cies, infested with a miinite ])arasite of the family Aca- 

 rida\ These parasites are of a bright vermillion-red color, and 

 fix themselves, one or more, at the sutures of the tergum, not 

 i|uitting their hold after the death of the insect, unless disturbed. 



'J'his species bi-gins to appear, soon alter the Small vSnow-fly is 

 first met with. It occurs in the same situations, is nearly as 

 abundant, and remains for a time alter that has disappeared. One 

 of the purposes served by these jirolilic insects in the economy of 

 natme, doubtless is, to sujiply with food tlu; fisii of our streams, 

 at this eai ly ])erio(l of the year. The larger of these species, con- 

 tinuing to be abundant when the the shad fust com(! intooin- riv- 

 ers, has evidently received one of ils popular designations in al- 

 lusion to this fact. 



We regard this as the American analogue of the Eurojiean 

 JSTcnioura nebuhsa^ Linn. J5ut, from several points in the extend- 



