Adults emerge in late June, reach peak abundance by mid-July, and decline through early September. They feed, mate and bask at the water's edge on warm, sunny days. Some adults are also active on warm, calm evenings. High body heat is necessary for maximum predatory activity. Adults also regularly scavenge dead crabs and fish.
Females deposit their eggs in the sand after mating, higher up the beach in the dunes.
Eggs hatch and larvae appear in late July and August. Most overwinter as second instars. Next year, these same individuals overwinter again, this time as third instars. Both second and third instars emerge from winter inactivity in mid-March. Third instar larvae emerge, pupate in the bottom of their burrows, and re-emerge as winged adults in June, two full years after the eggs were laid.