UHLER ON INSECTS. 787 



Caiiou 01 the Arkansas, August 11. No specimeus occurred to me in 

 the region north of the Arkansas Eiver ; but in that valley it was to be 

 seen singly in various places, from Pueblo westward to near the mount- 

 ains. 

 Priocnemis flammipennis Smith. 



Found singly on the highlands west of Denver, August 18. 



Fam. SCOLIAD^E. 



TijJhki alhilahris St. Farg. 



Seen in small numbers on flowers in the vicinity of Colorado Springs, 

 August 13 and later. 

 Myzine hyalina Cressou. 



This very slender relation of our eastern species was quite common 

 on the flowers of golden-rod, in Clear Creek CaQon and in Beaver Brook 

 Gulch, August 6 and 7. Two or three specimens were to be seen on 

 each head of flowers, and they were enjoying themselves in the bright, 

 hot sunshine by meandering through the florets and dusting their bodies 

 with a good coating of the yellow pollen. Only males were seen. 



Fam. MUTILLID.E. 



Mutilla hiocidata Cresson. 



Common in and near the mouth of the Canon of the Arkansas, August 

 10 and 11. 



Mutilla occidentalis Drury. 



One female of this large red species was found among the stones on 

 sandy ground in the valley of the Arkansas east of Canon City, August 

 10. 



Fam. FORMICID.E. 

 Formica nifa Linn. 



The neuters and females of my specimens correspond so closely with 

 the descriptions and figures of F. rufa Linn., that I am impelled to refer 

 them to that species. They abound on the plains in certain localities, 

 extending all the way from near Denver to just a little distance from 

 the valley of the Arkansas. It is the hillock-building species of the 

 plains adjacent to the mountains, and seems to belong to most sandy 

 situations not strictly within the limits of the alkaline soils. A closely 

 allied, if not identical, species undermines the soil on the south bank of 

 the Arkansas River, just inside the mouth of the Grand Caflon, and 

 there exists in countless multitudes. 



Many other kinds of the genus Formica, Myrmlca, and allied genera 

 inhabit the plains and mountains of Colorado, but it is not i)0ssible for 

 me to give a list of their names. The houses in Denver City and Colo- 

 rado Springs are infested with swarms of minute Myrmicas, just as we 

 have them on the Atlantic side of the continent. In two or three places, 

 I found it difficult to secure my collections from their insinuating pro- 

 pensities. 



