It is nearly one month past the summer solstice and here in southern Wisconsin, the glow of fireflies at dusk and into darkness is a summertime pleasure not to be missed.
Fireflies employ the substrate luciferin and the enzyme luciferase, to produce their bioluminescence. The flash of a firefly lantern is designed to attract a mate, although with some species the potential mate becomes prey. Different species of fireflies have different flash patterns, which helps them find one of their own, when pairing off to create new little shiners.
In contrast to showy bioluminescence during night time flight, ocean depths have luminescence displays from a wide variety of creatures. Many of these bioluminescent sea creatures are recent discoveries, their discovery, habitat and behavior identified with the use of mini-submarines and non-manned submersibles.
One glowing example is the cluster wink snail. Terrestrial snails have been noted to leave a slightly luminescent trail of snail mucus as they crawl. But in 2010, the cluster wink snail was noted to flash a bright green light throughout its entire shell. What better than an illuminated shell?
The snail has been noted to light up when disturbed, perhaps because the light makes the snail look larger. Or the bright flash may attract larger predators to come closer, scaring away the initial interrogator.
Here in the northern hemisphere, there are a variety of start dates for the beginning of summer. For parents of young children, summer may start the day after school ends. For others, Memorial Day and the associated long weekend is the start to summer. And of course there’s the vernal equinox, the longest day of the year, on or around June 21, for those that favor official timelines.
For yet others of us, summer begins with a trigger from nature: The first day above 90°F, or the day the tomatoes are planted, or when June bugs first appear on the back screendoor.
One of my favorite signs that summer is really here is the mid- to late-June appearance of fireflies. Few things are as magical as the displays of these flying bugs with their delicately flashing lanterns.