Common eastern firefly
This firefly flashes on a strict rhythm and only responds to a correctly timed return flash, letting it recognize others of its own species in the dark.
| Where | Meadows, lawns and woodland edges |
|---|---|
| Size | 9 to 19 mm body length |
| When | May to August |
The Common eastern firefly is a soft-bodied beetle 9 to 19 mm long, with dark brown to black wing covers edged in yellow and a pale, yellow-rimmed head shield marked with a black spot ringed in orange or red. Males fly at dusk on a looping, upward path while flashing, while females usually stay low on grass or ground.
Larvae live in soil and leaf litter for up to two years, hunting worms, slugs and snails, before adults emerge to fly through meadows, fields and yards across the warmer months. Both larvae and adults carry bitter defensive steroids called lucibufagins, which make them distasteful and, in enough quantity, dangerous to swallow for many predators.
Traits
Habitat
Grassland
Colour
Brown, Yellow, Orange
Active
Night
To people
Mild
Safe to touch, but its lucibufagin toxins can be deadly to pets and other animals that eat it.
Activity through the year
Often confused with
Adult females of this species mimic the flash replies of Common eastern firefly females in order to lure and eat the smaller species' males, and its body pattern is more mottled and less neatly yellow-edged.
Perches low on grass stems and gives a single steady amber glow rather than the repeated flashes the Common eastern firefly gives while flying.
Questions
Is the Common eastern firefly dangerous to people?
Mild. Safe to touch, but its lucibufagin toxins can be deadly to pets and other animals that eat it.
When can you see the Common eastern firefly?
The Common eastern firefly can be seen from May to August, at night.
Plate retouched from a photo by Katja Schulz, CC BY 4.0, iNaturalist Licence
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Last updated 2026-09-27. Every entry is checked against published sources.