The Bug Geek

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Tag Archives: Diurnal Firefly

Dark and light

In the dark understory of a deep hardwood forest, this large, langourous millipede lazily wound its way over the very rotten stump that was its home; here it attempts to cross a bridge to nowhere.   Several companions strolled nearby, presumably in search of food. 

A ray of sunshine broke through the dense overhead cover of bare branches and warmed a patch of soft, bright green moss.  A group of diurnal fireflies basked in the glow.

What are YOU doing out of bed?

That morning at the bird sanctuary, along with the birds and slugs and log-dwelling beetles, I was actually able to find MORE beetles WITHOUT FLIPPING A LOG.  Or PEELING BARK.  They were there, just so, fully exposed, soaking up the rays of early morning sunshine on the bark of an old Maple tree.

These pretty beetles may look familiar to some of you…the elongate, oval-shaped body, black elytra and red/yellow pattern on the thorax (which often hides the head from a bird’s-eye view) are quite characteristic of many Fireflies (Lightning Bugs) (Family Lampyridae).   However, usually Fireflies are active at night, blinking away with the bioluminescent organs at the tail-end of their abdomens in hopes of attracting a mate.  If we see them by day, they’re normally sleepy and resting; they are nocturnal animals.

These beetles were quite alert and active, strolling over the bumpy bark terrain.

I wondered what they were doing out of bed at such an ungodly hour.

I plucked one off the tree to have a better look…it had a soft gleam of all-over gold thanks to the dense cloak of fine yellowish hairs on the surface of the elytra and thorax.   And then I had a peek…er…”down there”.  Something was missing…the last few segments on most fireflies are usually pale greenish; it is here that a chemical reaction produces the characteristic night-time flickers of light.      This beetle lacked the pale organ.  I returned it to its tree and plucked a second…same thing.

Hm.   Day-active?  No bioluminescence?  Was I mistaken about these beetles’ identity? 

No.  These were, in fact, representatives of the genus Ellychnia…the Diurnal, or day-active, Fireflies. 

There are only about a dozen species of Dirurnal Fireflies in North America.  They lack the bioluminescent organs characteristic of their noctural cousins.  They overwinter as adults, in grooves of tree bark; the ones I spotted would have just roused from winter slumber.   They will begin mating in April and lay their eggs in rotting wood, where the larvae will spend their summers.

Speaking of Firefly larvae….  stay tuned.


Reference:  Ellychnia corrusca (University of Alberta)

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