Fireflies: Harbingers of Summer

In Southwest Virginia, summer is ushered in by the arrival of fireflies. As the days lengthen and become warmer, twilight is set aglow by the firefly’s lulling lightshow. The bugs are a well-loved sight for most Virginians, for they call to mind a magical point in the year: the in-between of spring and summer, when balmy temps and the lush green mountains are still novel, exciting, and filled with the promise of a burgeoning season ahead. To commemorate the beginning of firefly season, we thought we’d share some facts about these small but delightful creatures.


Photo by Jerry Lai.

The Common Firefly

Lampyridae (also known as fireflies or lightning bugs) are a kind of winged beetle with a conspicuous bio-luminescent abdomen. There are some 2000 species of fireflies distributed across the world, mostly in tropical or temperate climates. They prefer to live in ample humidity, which may be why Southwest Virginia is full of ‘em!

The light on their abdomens is chemically produced and can vary in color, from yellow to green to pale red. Their light shows are orchestrated in the hopes of finding a mate. Fireflies flash their bio-luminescent backs at alternating speeds, depending on what kind of information they’d like to send to potential mates. This is why fireflies sparkle rather than glow continually. In some cases, large groups of fireflies can even synchronize their flashes.

Once fireflies find a mate, the female lays eggs just below the surface of the ground. These eggs hatch in three of four weeks, and the larvae spend the rest of late-summer feeding. Firefly larvae are also bio-luminescent, and are thus sometimes referred to as glow worms. During the fall and winter months, they hibernate underground or in the bark of trees. In the spring, they emerge to pupate. After a pupation period of approximately two weeks, they reach adulthood and can begin to mate.

Fireflies don’t have many natural predators. They are poisonous to some and plainly distasteful to others. As long as spring is warm and wet, they can be expected to propagate in huge numbers, lighting up hillsides and fields like so many strings of twinkling Christmas lights. June is typically the highlight of firefly season, so–if you have yet to see any–set up camp in a quiet, rural place right about dusk and wait to be amazed. Their coruscating dance is an ode to summer that never lacks freshness or awe.


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