View Full Version : What's the wattage (or candlepower?) of a fiefly?

04-17-2003, 11:43 AM
And where do they live? (I've only seen them once, in central Indiana.)

04-17-2003, 12:12 PM
They seem to be all up and down the East Coast. Other than that I don't know.

For wattage, try comparing one to a small flashlight. I haven't done this, but I would guess that a penlight would have to be about four times farther away to appear the same brightness as a firefly. Inverse square law says the power output is 16 times less. A small flashlight like that might be 1-5 Watts, I'd guess.

However, an incandescent bulb wastes a lot of energy in heat. A firefly is much more efficient, maybe ten times more. So my best guess would be about 1/100 to 1/1000 of a Watt.

04-17-2003, 01:29 PM
For measuring levels of light the human eye can detect, the units you're talking about are lumens or footcandles. This might help to search for the answer.

04-17-2003, 01:44 PM
This page, http://extlab7.entnem.ufl.edu/IH8PCs/vol4/v4n42.htm, claims that A sixty-watt, inside-frosted light bulb produces 835 lumens. It would take more than 137,000 fireflies flashing simultaneously to give out as much light.I'm not sure where those numbers come from, though, unless it's from the research of this guy: http://entnemdept.ifas.ufl.edu/lloyd.htm. He's got a list of at least ten publications about fireflies. You might want to contact him directly for more information.

Sock Munkey
04-18-2003, 07:30 AM
I suppose you could just catch a firefly and hold it up to a light meter.

04-18-2003, 09:05 AM
The figure of 137,000 fireflys to equal a 60 watt bulb seems high. This site (http://www.isat.jmu.edu/users/klevicca/isat453/Web/luciferase.htm) and others claim that a firefly puts out about 1/400 candlepower. At 12.566 lumens/candlepower that's 0.0314 lumens per firefly. 850 lumens/0.0314 gives 27070 fireflys per 60 watt bulb.

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