APPLE-MIDGE FLIES SIMILAR TO IT. 255 



decaying trees, beneath the bark. The genus is somewhat ex- 

 tensive, nearly thirty species occurring in Great Britain alone, 

 and they appear to be equally common upon this side of the 

 Atlantic. Three of our species have been described by Mr. Say, 

 and several others are in my own collection. Our most com- 

 mon species occurs from the last of June till the middle of Au- 

 gust, in woods and in the yards about our buildings, and may 

 frequently be met with upon the windows in our houses. It may 



be named 



The Common midge, Molobms vu'garis. It measures 0.10 to 0.12 in length, 

 and is black, with blackish brown legs and pale thighs. Its poisers are whitish, 

 and its wings hyaline. The sides of its thorax below the wings are tinged with 

 pale, and the abdomen with brown, rarely pale. 



Another common species found in the same situations and at 

 the same dates with the preceding, and quite similar to it in its 

 colors, may be distinguished from it by its much larger size and 

 the smokiness of its wings. 



The Smoky-winged midge, Molobrus fuliginosus, measures 0.18 in length, 

 and is black with blackish brown shanks and pale thighs, their haunches being 

 commonly white. Its wings are semi-transparent and smoky. The sixteen 

 cylindrical joints of its antennas are more widely separated from each other by 

 short intervening pedicles than in the preceding species. The gravid female, 

 when pinned, extrudes her eggs, connected together in a continuous string. 



A smaller species than either of the preceding, attracted my 

 notice from the singular manner in which it ran about upon 

 the paper on which I was writing, one night the latter part of 

 December. As other individuals were found at the same period 

 upon the windows, there is little doubt they had hatched from 

 the earth in some flower pots which were in the room. This 

 tiny insect would advance very rapidly two or three inches and 

 then abruptly pause or move backwards a step or two and in- 

 stantly run again in another direction about the same distance, 

 and then back up again and start off in another course. It is 

 quite similar to the Molobrus (Sciara) femoratus of Mr. Say, which 

 like the foregoing, is a common species on windows in the month 

 of July, but here the abdomen is of a uniform color, or pale 

 only at its tip. It may be named in allusion to its mode of 

 running, 



The Fickle midge, Molobrus inconstans. It measures 0.08 in length, and 

 is black with the thorax smooth and slightly shining, the thighs pale and 

 whitish, and the wings pellucid and glassy with an iridescent violet and red 

 reflection. 



