102 Myron Harmon Szvenk 



Nebraska, principally along the Missouri bluffs, being replaced 

 by the following form from about the 97th meridian westward. 

 It has been collected at Weeping Water, South Bend, Ashland 

 and Lincoln, from May 18 to July 20; fairly commonly at flowers 

 of Erigeron philadeJphicns and Zizia aurea, in May. 



Nomada (Nomadula) articulata dacotana (Cockerell). 



1903. Noinada auiericaiia dacotana Cockerell, Proc. Acad. Nat. Sci. 

 Phil, p. 592, 6- 



As noted above, in eastern Nebraska part at least of the males 

 of articulata {^^=-auicricana auctt.) are typical, having the meso- 

 scutum wholly black, but from about the 97th meridian westward 

 we get a rapidly increasing suffusion of reddish on the meso- 

 scutum and an increase in the extent of the red on the abdomen, 

 which in its extreme phase has these parts almost entirely red. 

 Before the writer is a series of thirty specimens of dacotana, 

 from Lincoln, South Bend, West Point, Neligh, Springview, 

 Halsey, Crawford, Harrison and the Pine Ridge, collected May 

 18 to July 9, which show that this color variation is correlated 

 with geographical distribution, as the reddest specimens come 

 from western Nebraska and the eastern Nebraska specimens 

 intergrade with typical articulata. The variation is quite parallel 

 with that observed in Nomada {Micronomada) modesta and its 

 race vegana. N . a. dacotana is common at flowers of Erigeron 

 philadclphicus, Fragaria virginiana, Apocyniim cannabinum, 

 Asclepias syriaca, Symphoricarpos occidentalis, Convolvulus 

 arvensis and Mclilotus alba eastwardly, and in the Pine Ridge on 

 Scnccio atriapiculatus and Sedtiin stcnopetalum. 



Nomada (Nomadula) scita Cresson. 



1878. Noinada scita Cresson, Trans. Am. Ent. Soc, VII, p. yy, d*. 

 1903. Nomada martinella Cockerell, Proc. Acad. Nat. Sci. Phil., pp. 



590-91, $. 

 1903. Nomada (Nomadula) martinella Cockerell, Bull. 94, Colorado 



Exp. Sta., p. 76, ? d". 

 191 1. Nomada scita Cockerell, Proc. U. S. Nat. Mus., XXXIX, p. 648. 



This species is confined in this state to the northwestern corner, 

 where it is rather common from May 26 to July 12, at flowers of 



102 



