Warm weather could account for sightings of the first fireflies.

The first fireflies were seen and reported on the wing May 19 in the Lanesboro area, and May 26 in Faribault, Lakeville, White Bear Lake and the Waconia area.

Fireflies first appeared June 10 in the Waconia area last year.

The common names firefly and lightning bug are used for insects that communicate with pulsating “taillights” — segments at the ends of their abdomens. It’s there that light is produced by a chemical reaction controlled by the supply of air entering through minute openings. There are 136 species of fireflies, which are soft-bodied beetles, in eastern North America, and about 15 are found in Minnesota.

Here in our state, north to south, the prime time to see the little specks of light is now through July. Wetlands; wet ditches; tall, grassy spots; old fields; forest edges; and sometimes lawns near more natural areas are good places to observe them.

The flash of light is a recognition signal, enabling the sexes to find each other. Each firefly species has a characteristic flashing rhythm. A male will emit flashes of yellowish light at intervals of a few seconds while it flies a few feet from the ground and on up to treetop level. Females wait on top of lower vegetation. They will flash back if a flashing male of their species comes within about 6 feet. The exact number of seconds between flashes distinguishes the species.


Jim Gilbert’s Nature Notes are heard on WCCO Radio at 7:15 a.m. Sundays.