Males swarm during rainstorms. In eastern and southern Texas this swarming period is always late in the year, Oct-Dec. These are likely mating swarms, but I have never found a female, and it is likely that females do not fly and probably leave the soil only very briefly to attract a mate. (Ed Riley, 2008 pers. comm. to MAQ)
Horn G.H. (1881) Notes on Elateridae, Cebrionidae, Rhipiceridae and Dascyllidae. Transactions of the American Entomological Society 9: 76-90.
Turnbow R.H., Wappes J.E. (1977) Note on a flight by males of Scaptolenus ochraetus Horn. The Coleopterists Bulletin 31(4): 346.
Werner F.G. (1969) Two flights of Scaptolenus (Coleoptera: Cebrionidae). The Coleopterists Bulletin 23(1): 26-27.