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Sticker of Douglas fir glow-worm
Bug card No. 1410 of 4,939

Douglas fir glow-worm

Pterotus obscuripennis

The Douglas fir glow-worm is a firefly from the west coast of North America. The female has no wings and looks like a big larva, and she glows in the dark. The male is smaller, can fly and does not glow at all.

Lives in
The west coast of North America, from Washington to California
Length
0.9 to 3.5 cm (0.37 to 1.4 in)
females 25 to 35 mm, males 9.5 to 12 mm
Top speed
about 5.1 km/h (3.2 mph)
Flying, estimate
Can it hurt you?
Harmless
Harmless to people. It only hunts slugs and snails.
What does it eat?
Its larvae hunt slugs and snails. They give them a bite that makes them stop moving, then eat them.
For real!Photo of Douglas fir glow-worm
Picture by Judy Gallagher. CC BY 2.0, via Wikimedia Commons.

How big is it?

How long is it?

Douglas fir glow-worm about 3.5 cm long (1.4 in)A toy building brick about 3.2 cm (1.3 in)A crayon about 9 cm (3.5 in)A banana about 18 cm (7.1 in)
as long as 6 grains of rice in a rowcould fly across a whole football pitch in 74 secondsmoves 40 times its own body length every second

How big is Douglas fir glow-worm compared to YOU?

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How fast is it?

cool stuff

Fun facts

1

The female is about three times as long as the male.

2

Its larvae are black with white rings between the body parts, and they glow too.

3

The larvae often glow brightly while they eat.

4

A larva can go up to three months without food.

5

It has a special part on its tail end that it uses to clean slug slime off itself.

you asked

Most asked questions about Douglas fir glow-worm

?Does the Douglas fir glow-worm glow?

The females and the larvae glow, but the males do not.

?What does the Douglas fir glow-worm eat?

Its larvae eat slugs and snails.

For bug experts

Scientific name
Pterotus obscuripennis
Group
Beetles
Family
Lampyridae
Classification
Insecta > Coleoptera > Lampyridae
Lives on
North America
Also known as
Douglas fir glowworm

Where the facts come from

  1. Pterotus obscuripennis (Wikipedia, CC BY-SA 4.0): what it looks like, where it lives, what it eats, sizes and fun facts, retold in simple words.
  2. Picture by Judy Gallagher. CC BY 2.0, Wikimedia Commons. The sticker of this bug is drawn from this picture.

If we got something wrong, sorry, we are bug fans, not a science journal. Tell us at [email protected] and we will fix it.

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