Cold light
It makes light by a chemical reaction in its tail. Almost none of the energy is lost as heat.
An American yard · Beetles
Common eastern firefly
Photinus pyralis
A small, soft, dark beetle with a yellow and red shield over its head, and a tail that lights up.
- Size
- 1 to 1.5cm long
- Look for it
- May to August
- Where
- Lawns, meadows and woodland edges in eastern North America
Drifts after you, flashing. Move your pointer and see.
When to look
Firefly
Good to know
Six things about the firefly
Flashing in code
Each kind of firefly has its own pattern of flashes. Males fly and signal, and females answer from the grass.
A letter J in the air
This kind dips and rises as it flashes, drawing a glowing J. It is sometimes called the big dipper firefly.
Not a fly
Fireflies, or lightning bugs, are beetles. Glow-worms in Britain are their cousins.
A deadly copycat
The females of one kind imitate the flashes of others, and eat the males that come to them.
The young glow too
The grubs live in soil and leaf litter, eat slugs and snails, and give off a faint light.
The real thing
Photos of the firefly
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Photos are from Wikimedia Commons, used under the free licences shown. They have been resized, and cropped where they appear in link previews.
How to spot one
Stand at the edge of a lawn at dusk in early summer. The flashes start low over the grass as the light fades. Take an adult with you.
How to help
Fireflies need darkness, long grass and damp ground. Switching off garden lights in June makes a real difference.
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