172 DURHAM DIPTERA 



XXVIII. 



Sub-Family Chrysotoxinje. 

 99 (104). Arista dorsal. 



100 (101). X.4. beyond the middle of O., third antennal joint 



very short. Sphecomyia, Ltr. (vitatta, Wd.) 



101 (100). X.4. before or at the middle of O., third antennal 



joint usually the longest. 



102 (103). Antennae placed on a long stalk (VI. 18), abdomen 



with a broad orange band. 



Psarus, Ltr. (abdominalis, F.) 



103 (102). Antennae placed on a prominent frons (III. 46), 



abdomen with " golden bows." 



Chrysotoxum, Mg. (318) 



104 (99). Style terminal. Callicera, Mg. (1624. cenea, F.) 



105 (98). V.3. with a veinlet on its under side almost divid- 



ing 0.4 2 . 



Sub-Family Microdontin^e. 



Microdon, Mg. (320) 



TABLES OF SPECIES. 



270. Paragus, Ltr. 

 Larvae feed on Aphides. 



1 (2). Scutellum entirely black, and the face with a black 



middle line in both sexes. (1426. tibialis, Fin.) 



2 (1). Scutellum with at least the tip pale in female, and 



face entirely yellow in male. (1427. bicolor, F.) 



271. Pipizella, Rnd. 

 Larvae aphidiphagous. 



1 (6). Upper outer corner of 0.4 2 almost a right angle. 



2 (5). Pubescence on hind tibiae pale. Abdomen unspotted. 



3 (4). Short, brassy, greenish-black species. 



1428. Pipizella virens, F. 

 Hesleden, 1 $, August, 1902. 



4 (3). Rather long bluish-black species. 



(1429. maculipennis, Mg.) 



