97 



" 4. Nemoura nivalis. The Large ' Snow-fly.' The ' Shad-fly.' 



" Black ; wings griseous, faintly handed, double the length of the abdomen. 



" Length, males somewhat under, females over, half an inch ; wings expand about 

 an inch. 



" It is not uncommon to meet with specimens of this and the preceding species, 

 infested with a minute parasite of the family Acaridae. These parasites are of a bright 

 vermillion-red colour, and fix themselves, one or more, at the sutures of the tergum, 

 not quitting their hold after the death of the insect, unless disturbed. 



" This species begins to appear soon after the small snow-fly is first met with. It 

 occurs in the same situations, is nearly as abundant, and remains for a time after that 

 has disappeared. One of the purposes served by these prolific insects in the economy 

 of nature, doubtless is to supply with food the fish of our streams at this early period 

 of the year. The larger of these species, continuing to be abundant when the shad 

 first come into our rivers, has evidently received one of its popular designations in al- 

 lusion to this fact. 



" We regard this as the American analogue of the European Nemoura nebulosa, 

 Linn. But, from several points in the extended description of that species given by 

 M. Ramber (' Suites a Buff on,' Insectes Neuropteres, Paris, 1842), it is quite obvious 

 that ours is a distinct insect. 



" 5. Culex hyemalis. The Winter ' Musketoe.' 

 " Thorax cinereous, with a broad black vitta on each side ; extreme tips of the wings 



and two spots on their anterior margins black, with two intervening sericeous yellowish 



white spots. 



" Length 0.22 ; to the tips of the wings 0.28, or including the beak, 0.39. 



" The winter musketoe is met with in the last days of autumn, and again for a short 



time in the first days of spring, and specimens are occasionally found in any of the 



winter mouths. It is a somewhat rare insect, which no one can fail to distinguish 



clearly by the marks on its wings, as above described. 



" 6. Chironomus nivoriundus. The Snow -born Midge. 



" Black ; poisers obscure brown ; wings pellucid-cinereous, their anterior nervures 

 blackish. 



" Length about 0.15 to the tip of the abdomen in the males; females a third 

 shorter. 



" This is a very common species, appearing upon the snow in the winter season, 

 and upon fences, windows, <Scc, in the fore part of spring, the males and the females 

 being about equally numerous. The beautiful plumose antennae of the former distin- 

 guish them at a glance from all other insects abroad at this season. At times they 

 may be met with in immense swarms. April 27th, 1846, in a forest, for the distance 

 of a fourth of a mile, they occurred in such countless myriads as to prove no small an- 

 noyance to the passer, getting into his mouth, nostrils and ears at every step, and li- 

 terally covering his clothing. These had probably hatched from the marshy border of 

 an adjoining lake, on this and the preceding days, the weather having been remarka- 

 bly warm and dry. The wings appear to be more hyaline and iridescent in those in- 

 dividuals that come forth earliest, but I am unable to detect any marks by which they 

 may be characterized as specifically distinct from those which appear at a later day. 



N 



