Bug Identifier

Beetles

Firefly

Photinus pyralis

048121620
Body length in millimeters. Shaded bar shows the typical adult range.
Scientific namePhotinus pyralis
GroupBeetles
Size10–14 mm (up to about 0.55 in)
Colors Black, Red and Yellow
Legs6 legs
WingsYes
Where foundLawn or grass and Woods or trails
Most activeSummer
BitesNo
StingsNo
Risk levelHarmless

How to identify it

The firefly is a small member of the beetles group. Hard wing covers that meet in a straight line down the back. Check for these three features:

  1. Pink or red shield on the thorax with a black center spot
  2. Pale, light-producing segments at the tip of the abdomen
  3. Soft, flexible wing covers edged in yellow

About this bug

A soft-bodied beetle that flashes a yellow-green light from its abdomen on summer evenings. Each species uses its own flash pattern to find mates.

You'll usually find fireflies in lawns and grass and in woods and along trails. They are most active in summer.

Is it dangerous?

Fireflies do not bite or sting, but they contain chemicals that are toxic to lizards and some pets if eaten.

Our rating: Harmless, meaning it poses no real threat to people, pets or property.

When you'll see fireflies

Fireflies are most active in summer. Summer heat speeds up development, so populations can grow quickly.

Typical places to check: lawn or grass and woods or trails.

About beetles

The firefly is one of the beetles. Beetles go through complete metamorphosis: egg, larva (grub), pupa and adult. The larval stage often does the most feeding and damage, and it can last from a few weeks to several years depending on the species. Adults protect their flight wings under hard wing covers called elytra, which is why most beetles look armored and meet in a neat line down the back.

Look closely at larvae as well as adults. Grubs in soil, fuzzy larvae in closets and small worms in flour are all beetle larvae, and finding them tells you where the problem is centered.

Should you get rid of it?

No control is needed. Fireflies are not pests, and many help by eating other insects or pollinating plants. If one is indoors, move it outside with a cup and a sheet of paper.

Bugs that look similar

Blister BeetleEpicauta spp.8–25 mmCan bite or sting

Size: Blister Beetles are larger, reaching 25 mm, while fireflies top out around 14 mm.

Frequently asked questions

What does a firefly look like?

Pink or red shield on the thorax with a black center spot. Adults measure 10–14 mm (up to about 0.55 in).

Does the firefly bite or sting?

It does not bite. It does not sting. Fireflies do not bite or sting, but they contain chemicals that are toxic to lizards and some pets if eaten.

Where do fireflies live?

Fireflies live in lawns and grass and in woods and along trails.

When are fireflies most active?

Mostly in summer.