Handbook of Nature-Study · Lesson XCIV · Topic 14: Mosquitoes, flies and beetles
94. The firefly
Goal: Your child can describe when and how fireflies flash, find the light organ on the beetle, and explain that the flashes are signals.
You'll need
- A warm, damp summer evening in a yard or field
- A clear jar with a damp paper towel and a cloth cover
- A small flashlight
- A nature notebook and a pencil (colored pencils if you have them)
What's in the book
Comstock's story of fireflies "sown upon the night": which nights they fly, how high different kinds fly, how the light is made, and the glowing young. Then Lesson XCIV's leading thought, method and eight questions, with a verse by Lowell and a photograph of a beetle in flight.
The lesson, step by step
When and where
Warm, still, damp evenings from June into August, at dusk, over lawns, meadows and the edges of woods.
Keep the big idea in mind
Comstock's "leading thought" is the one idea the lesson is meant to lead to. Read it to yourself now, and save it to share at the end, after your child has looked and answered:
When the firefly wishes to make a light, it can produce one that, if we knew how to make, would greatly reduce the price of artificial light; for the light made by fireflies and other creatures, requires less energy than any other light known.
Watch the evening
Do they begin to lighten before it is dark? Do you see them high in the air or near the ground? Is the flash they give short, or long enough to make a streak of light? Do you see them on cold and windy nights or on warm, still, damp evenings?
Make a note of the hour when you see the first one flash in an evening.
A closer look
Catch two or three gently in your cupped hands and put them in the jar with the damp towel.
Can you see the light when they are not flashing? What color is it? When they make the flash can you see the outline of the "firefly lamp?"
Watch closely and see if you think the flashing is a matter of will on the part of the firefly. Do you think the firefly is signaling to his mate when he flashes?
Fly or beetle?
Is it a fly or is it a beetle?
Turn the beetle on its back. Can you see the part of the body that flashes? What color is it?
Look through the side of the jar instead of turning it over yourself. Then let the fireflies go where you caught them, the same night.
Talk back
Fireflies really are signaling: each kind has its own pattern of flashes, and the females answer from the grass. Count the seconds between one firefly's flashes, then try answering with a quick blink of the flashlight held low.
Nature notebook
Draw a firefly from below with its glowing tip colored in, and a dark night scene with the flash paths as dots or streaks. Write the date and time of the first flash. Read the leading thought aloud.
Afterwards
Comstock asks: "Do you know the life history of the firefly? What is it like in its earlier stages?" Look for glowworms, the young, glowing in damp grass and leaf litter on late-summer nights.
Tip
Fireflies are fewer in many places than they used to be. Leaving a corner of the yard unmowed and turning off outdoor lights on summer nights helps them.