301 



FAMILY CHARACTERS 



Larva. — Head complete; mandibles opposed,, antennae elongate. 

 Larva peripneustic, having prothoracic and elevated lateral abdominal 

 and apical abdominal spiracles, the latter situated upon 2 widely 

 separated stalk-like protuberances. Body with slender hairs. 



Pupa. — Head without thorns ; antennae curved over upper portion 

 of eyes. Thoracic respiratory organs pedunculate, in the species be- 

 fore me furcate. Wings short; apices of hind legs barely extending 

 beyond apices of wings. Abdomen unarmed ; spiracles elevated, stalk- 

 like. 



Imago. — Separable from Bibionidae by the wing venation. (See 

 key to imagines of Nematocera.) 



HABITS OF LARVAE 



The larvae of this family are scavengers, feeding in manure and 

 on decaying vegetation. I have also found them under loose bark of 

 fallen trees. 



HABITS OF IMAGINES 



The flies are found on flowers, manure, decaying fruit, and very 

 frequently on windows. 



RhegmocIvEma atrata Say 



Scatopse atrata Say, Appendix to Keating 's Narrative of an Expedition to the 



Source of St. Peter's Eiver, p. 367. (1824) 

 Scatopse fuscipes Meigen, Syst. Besehr. Enr. Zweifl. Ins., Vol. 6, p. 314. (1830) 

 Scatopse recurva Loew, Linnaea Ent., Vol. 1, p. 330. (1846) 

 SJiegmoclema atrata (Say) Melander, Bull. 130, Wash. Agr. Exper. Station, p. 



12. (1916) 



Larva (PI. XLV, Fig. i). — Length, 3-4 mm. Yellowish gray; 

 head brownish yellow; surface hairs on body pale brown; spiracular 

 protuberances blackish ; apical respiratory processes brownish yellow ; 

 apical processes caudad of the latter black. 



Antennae longer than in Bibio (PI. XLV, Fig. 8). Pseudoseg- 

 ment indistinguishable ; prothoracic spiracles more distinctly elevated 

 than the abdominal pairs ; metathorax without spiracles. Entire body 

 covered with rather short slender hairs. Apical segment with 4 

 processes on dorsum — a pair near base which are stouter than the pre- 

 apical pair and bear the spiracles, and a much more slender pair near 

 apex which are crowned with several short hairs. Abdominal spiracles 

 slightly elevated. 



