W. M. DAVIDSON 41 



the shining spots ave (Ustinctlj'' gruy and not bronze. In the 

 female these spots are orange, and the; abdomen is more oval. 

 Thomson described his species from California. 



Key to the Species of Melanostomn described or mentioned al)ove 



I 



Pollen ot'faco in obscure ripjjlcs, im])uiicf ;it(> 3 



Pollen of face punctate 2 



2. Face with a shining black stripe, vertical chaetopoda new species 



Face with but the tubercle shininji stegnum Say 



3. Profile of face almost perpendicular, not obviously rostrate. 



Ontario new species 



Profile of face rostrate, the epistoma i)rojectino; considerably bej'ond the 



facial tubercle 4 



4. Thorax shining sreenish-})lack, the facial stripe broad obscurum Say 



Thorax shining bluish-black or bluish-gray, facial stripe narrow. 



obscurum Say, var. rostratum Bigot 

 II 



Facial tubercle alone shining stegnum Say 



Vertical shining stripe on the face, but not reaching the antennae 2 



2. Facial profile njstrate, tlie epistoma jirojecting considerably i)eyond the 



facial tubercle of knob 3 



Facial j)rofile j)crjjendicular, the epistoma not iirojecting beyond Ihc facial 

 knob 4 



3. Thorax greenish-black, facial stripe broad obscurum Sa^- 



Thorax bluish-black or bluish-graj', facial stripe narrow. 



obscurum Say, var. rostratum Bigot 



4. Facial pollen punctate chaetopoda new species 



Facial pollen in obscure rip))Ie-like formations and iiiii)unctatc. 



Ontario new species 



Biological Notes 



Melanostoma stegnum Sa}- (PI. I, fig. D.) 



A gravid female was collected in the field at Alhambra, Calif- 

 ornia, on March 11, 1920, and transferred to a ehinniey cage en- 

 closing a young broad })ean plant infested with Aphis rumicis 

 Linnaeus. The fly was fed with sugar water and died March 20, 

 after having deposited ninety-seven ova on the foliage. These 

 ova in many cases were ranked side ])y side or end to (muI, but 

 a few were laid singly. The ovum is cylindrical, elongat(>, rather 

 sharply tapei-ing at each, more so at the non-microiiylar end; 

 white, not chalky; clioi'ion sculjitured with regular hexagonal 

 markings, small and not elevated; size of ovum .88 nnn. x .32 mm. 



TliANS. AM. ENT. .SOC, XI.\ ni. 



