Observations indicate that Formica obscuripes flies earlier in Nevada than in other parts of the country where the flights have been recorded. The alate males are the first to emerge from the nest. These are eventually succeeded by alate females, and finally only females are seen. F. obscuripes flew during periods when air temperatures were 20.5–26.5 C, when relative humidities were about 18%, and when solar input was about 1.35 langleys. Slight winds approaching 3 mph did not keep the ants from flying but may have influenced their direction of flight.
The nests of F. obscuripes observed near Reno differ from those reported in other areas in that they do not have such an extensive thatch covering them.
Clark, William H. and Comanor, Peter L.
"Flights of the western thatching ant, Formica obscuripes Forel, in Nevada (Hymenoptera: Formicidae),"
Great Basin Naturalist: Vol. 32
, Article 3.
Available at: http://scholarsarchive.byu.edu/gbn/vol32/iss4/3