1932] 
The Thatching Ant, Formica obscuripes 
33 
or more present. Winged males and females appear in 
large numbers during June and July. 
These ants feed chiefly on dead insects and related forms 
which they usually place in the brood chambers. Occa- 
sionally, however, they carry seeds into the mounds. 
Whether these seeds are used for food is evidently unknown. 
In a few mounds I observed them intermingled with the 
brood as is the case with the above food. 
Wheeler states 2 that he has observed whole colonies of 
obscuripes attending droves of young Membraeids in 
Colorado. I, too, have observed this association in Idaho 
and have also seen the ants attending two species of unde- 
termined aphids on sagebrush. Wheeler 2 lists Euphoria 
inda and hirtipes as among the synoeketes of obscuripes . 
LITERATURE CITED 
1 Wheeler, W. M. A revision of the ants of the genus Formica 
(Linne) Mayr. Bull. Am. Mus. Nat. Hist., Vol. 53, No. 10. (1913) 
2 Wheeler, W. M. Ants; their structure, development and behavior. 
Columbia Univ. Press. (1926). 
