Home > Great Big Greenhouse Blog > July 2014 > BONNIE'S GARDEN--Baby, Light My Fire--Fly that is.

BONNIE'S GARDEN--Baby, Light My Fire--Fly that is.

One of the things I enjoy most in my wildlife friendly yard is watching the fireflies in early summer.  What kid hasn’t run around their back yard at dusk chasing fireflies?  When I was a kid, I remember summer evenings at my grandparents’ house in Victoria.  My grandparents, my parents, even my favorite aunt and uncle all sat on the front porch, drinking iced tea.  My sister, brother and two cousins and I ran around the huge front yard catching fireflies and holding them in our hands.  Years later, those memories are still so vivid—maybe because everyone I loved most in the world was together in one place.  Twenty years later, I sat in my own yard watching my two kids run around, chasing fireflies.  And, one day, I’ll be the grandma that sits on my porch, watching my grandchildren doing the same.

Fireflies aren’t flies at all, but beetles, belonging to a family called Lampyridae.  There are several species of fireflies native to Virginia.  Most belong to either the genus Photinus or Photuris.  Fireflies like grassy or wooded areas near water sources.  They also like warm humid weather—welcome to Virginia in the summer! 

Fireflies produce light with cells called photocytes which contain a chemical called luciferin.  An enzyme, called luciferase, interacts with the luciferin to make light.  The light produced by a firefly is cold—generating no heat.  Nearly 100% of the energy used is given off as light.  In contrast, the energy used by a regular incandescent light bulb gives off 10% light and 90% heat. 

Fireflies spend most of their lives as larvae—glow worms.  The larvae are predators and feed on slugs, snails and other insect larvae.  The females lay eggs soon after mating and the larvae hatch shortly thereafter and feed all summer.  They hibernate over winter, feed again in the spring, then pupate for a short two week period before hatching in early summer. 

It’s usually the males we see lighting up our yards on a summer night, signaling for a mate.  Each species has its own particular signal pattern.  The females tend to wait in trees or shrubs.  When she sees a prospective mate, she signals back.  Some females of the genus Photuris, however, use signaling for a more sinister purpose.  She’ll mimic the flashing pattern of females of a different species and when the male approaches expecting to find a girlfriend, he becomes lunch instead.  Most firefly females aren’t cannibals however.  Adult fireflies live only a few weeks.  Some species eat nothing at all while they are adults; others may eat only a little nectar or pollen.

Some experts are concerned that firefly populations are dwindling.  So much of their native environment has been destroyed.  So many ponds filled in to turn into housing developments.  Scientists have also found that fireflies are sensitive to the same chemical pesticides that are killing our bees—neonicitinoids.  And excessive night time lighting—street lights, porch lights, even car headlights may interfere with their mating cycles.

There are two spots in the United States, Congaree National Park in South Carolina and the Great Smoky Mountains near Elkmont, Tennessee where the fireflies sometime in early June will inexplicably begin to synchronize their blinking.  Scientists are not sure why.  But that must be pretty incredible to see.  However they twinkle, they really light up our lives.

Posted: 7/12/2014 by Bonnie Pega | with 0 comment(s)
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