Photinus pyralis fireflies signal to each other at dusk in early summer. Males of this species draw distinctive, J-shaped swoops while females signal their interest from the grass. Homer Lake, Illinois, USA

Two species of fireflies active around sunset in an Illinois forest, one just above the forest floor (Pyractomena, the spots) and the other (Photinus) tracing lines a few feet above them. This photograph is a composite of many long exposures taken over a 23-minute interval. Homer Lake, Illinois, USA

During the day, night-flying fireflies like this Photinus pyralis sleep under leaves or in other inconspicuous hideouts. Urbana, Illinois, USA