Royal Alberta Museum: Invertebrate Zoology - Bug Facts

[Caterpillars and Other Immature Insects]

Fact Sheets: Commonly Observed and Asked About Insects and Spiders Found in Alberta

Boreal Firefly (Pyractomena borealis)

Boreal Firefly
Photo CD 0023 3291 1601, Image #11 - Credit: Terry Thormin

Boreal Firefly showing yellow light producing abdominal segments
Photo CD 0023 3291 1601, Image #12 - Credit: Terry Thormin

INTRODUCTION

When most Albertans first see flashing lights in a wooded or marshy area in Alberta, they find it hard to believe that we really have fireflies this far north. In actual fact there are at least eleven species of fireflies in Alberta, of which six species do not produce light.

IDENTIFICATION

In Alberta, if one sees an insect that produces a light at night, it is a firefly. In southern temperate areas and in the tropics there are other insects, including some click beetles that produce a light. Identifying adults during the day is a bit trickier. The Boreal Firefly is about 10 mm long, and fairly flat. It has flat black elytra (the modified front wings) and a pronotum (the area right behind the head) that is broad and black with two broad yellow stripes down either side. The last two segments of the abdomens are a pale yellow colour indicating that it is one of the light producing species.

DISTRIBUTION

The Boreal Firefly is found throughout all of Alberta in appropriate habitat. Fireflies are more common and have a greater diversity of species in southern temperate and tropical regions.

TIME OF YEAR

In Alberta fireflies are out from late May to early July.

HABITAT AND HABITS

The Boreal Firefly is generally found close to water as the larvae feed largely on snails. They can be seen flying over marshes, in river valleys and anywhere there is sufficient water to support snail populations. The light is used as a way to attract a mate, each species having its own distinctive signal. This is a cold light, being almost 100% light and virtually no heat. During the day light producing fireflies are usually inactive, resting on the vegetation. As stated earlier, not all firefly species produce light, and these species tend to be active during the day and will often come to goldenrod or aster flowers.

SIMILAR SPECIES

Trying to identify the various species of fireflies can be a real challenge. One can easily separate the species that produce light from those that do not as the non-light producing species lack the pale yellow segments at the tip of the abdomen. The Boreal Firefly is by far the most common light-producing species in Alberta.

COMMENTS

Most people that phone us about fireflies do so because they are amazed that they occur this far north. The fact that there are five light-producing species in the province is even more surprising. One interesting, and challenging project would be to try to determine the different flashing patterns of these species.

[Royal Alberta Museum Home Page] [Invertebrate Zoology]

For more information on this bug, please contact the Bug Room.
© Copyright 2000-2008, Royal Alberta Museum - ALL RIGHTS RESERVED
Last update: August 29 2008