36 Myron Harmon Sivenk 



continuous and laterally broad yellow band on tergite 2 (in 

 costaUs this band is reduced to short, lateral, linear spots, which 

 in the male are supplemented by two small discal spots in line 

 with the lateral spots), and in the presence of a band on tergite 

 5 in the female. The band on tergite i is broad and submedian 

 (narrow and apical in costalis) , while those on 3 and 4 are broad 

 and of uniform width, and not laterally emarginate on the 

 anterior margin in the female, rarely so in the male (narrow and 

 emarginate in costalis). From 6". rndheckiarum Ckll.. from 

 New Mexico (which is probably only a form of S. costalis), 

 the male differs as it does from 5". . costalis in the completely 

 banded second tergite, but one extreme specimen (Santa Rita 

 Mountains) approaches rndbeckianirn quite closely in its black 

 legs, tubercles, pleura and clypeus. From S. louisac Ckll., from 

 Louisiana, the male differs chiefly in the complete bands on 

 tergites 2 and 5 (these reduced to spots in louisae) and in the 

 lack of a large yellow pleural patch. In the abdominal banding 

 it agrees with 6^. laticincta Cresson, from California, but it is not 

 very close to that species, where the female has a large yellow 

 pleural patch, yellow postocular lines and the legs black except 

 for yellow spots on the knees and a yellow line on anterior tibiae, 

 while the male has a wholly yellow clypeus, a continuous yellow 

 postocular and occipital band, anterior and hind tibiae yellow 

 externally, etc. Possibly the arizonensis-costaUs-rudheckiarum- 

 lonisae group forms a single, highly variable southwestern 

 species. 6". ohesa Say, from Indiana, differs from arizonensis in 

 the interrupted bands on tergites 1-4, the yellow postocular lines 

 and mandible bases, the interrupted mesoscutellar band, the 

 largely yellowish legs, etc. 



Stelis (Microstelis) lateralis Cresson. 



O. A. Stevens has collected this species in North Dakota, a 

 male at Lisbon, June 5, 191 3, on Zizia aurea (4595), and five 

 females at Fargo, July 20-31, 191 3, on Lactuca pulchclla and 

 Solidago scrotina (5747-49, 5807, 6021). 



190 



