ACALYPTERATE FLIES. 



second) joint of each hind tarsus is usually short and 



broad. The adults of Borborus and Spharocera are often 



seen in clouds about the excrement in which the larvae 

 feed. 



The TETANOCERID^E (or Sciomyzidae) are somewhat 

 sluggish, usually brown or yellow flies, many of which 

 have receding chins and marking on the wings. See 

 Tetanocera (Plate LXVIII). They are usually found 

 in moist places, the larvae being aquatic. 



Sapromyza (Plate LXVIII) is fairly typical of the 

 LAUXANIID^;. They are small flies whose larvae live in 

 decaying vegetation. 



ORTALIDID^ 



The flies of this and the next family have prettily marked 

 wings. The distinctions between the families are, for the 

 most part, rather difficult to grasp; perhaps the easiest 

 concerns the auxiliary vein. In the Conopidae, Sepsidae, 

 Ortalididae, and other families, it is present and ends dis- 

 tinctly in the costa; in the Trypetidae, Drosophilidae, and 

 other families it is absent or incomplete. In the three 

 first-named families, the first longitudinal vein usually 

 ends in the costa, near or beyond the middle of the front 

 margin; in the two last-named ones, it usually ends before 

 the middle. Numerous species of Ortalididae are usually 

 found in meadows and some (e. g. Tritoxa flexa, Plate 

 LXXI) have been bred from onions but the life-histories 

 of most are unknown. The same plate shows Pyrgota 

 undata. 



TRYPETID^E 



The Peacock Flies spend much of their time strutting 

 about with brown- or black-spotted wings elevated and 

 waved back and forth. Some of the females have relatively 

 long, horny ovipositors at the tip of the abdomens. See 

 Euaresta, Plate LXXI. Most of the larvae live in plant 

 tissues. 



275 



