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State Insect of Pennsylvania Lesson: The Pennsylvania Firefly

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Pennsylvania's state insect is the Pennsylvania firefly. It was designated in 1974, the result of a campaign by elementary students in a school in Upper Darby who saw that neighboring Maryland had adopted a state insect (the beautiful Baltimore checkerspot butterfly). Deciding that their state should have one too, they petitioned the Pennsylvania General Assembly, which formally adopted the firefly as the state insect on April 10th.

The Pennsylvania Firefly's Scientific Name

Fireflies make up a large group of beetles, the family Lampyridae. The Pennsylvania firefly is only one kind of 2000 distinct species. It is in the genus Photuris, along with more than 60 other species that share distinctive features and an evolutionary lineage.

The specific name of this firefly is pensylvanica, which is not a typo – the spelling reflects the insect's 19th-century Latinized name. Put it together with the genus name and you get a big name for such a little insect: Photuris pensylvanica.

As a middle school teacher myself, I wrote this guide to be useful for both students and teachers. It's a great place to start for research ideas and science fair projects!

Photuris pensylvanica

Photuris pensylvanica

How to Identify the Pennsylvania Firefly

Fireflies – beetles in the family Lampyridae – often look very much alike, and most people are familiar with their general appearance. They are elongated, red-brown, with soft wing cover (elytra). It can be difficult to tell the difference between different species of firefly, since they tend to look alike.

Entomologists (people who study insects) have identified more than 2,000 different kinds of fireflies around the world. These fascinating insects are not flies at all, but rather beetles. They spend most of their time on the ground and on foliage, but at night they fly into the air and begin flashing signals to potential mates. Of course, there are many variations on this behavior.


Complete Metamorphosis

"Complete metamorphosis" is the term used to describe the life cycle of insects that go through a four-stage sequence of forms. For butterflies, this means egg-larva-cocoon/chrysalis-adult. It helps to take the butterfly as the example, although dragonflies, bees, wasps, flies, beetles, and many other insects also go through complete metamorphosis. Like butterflies, beetles also they all have larvae and all of the other developmental stages.

The life cycle of the firefly beetle can be seen as analogous to a butterfly's. The egg hatches into a larva that is something like a caterpillar, only in this case it eats other arthropods like worms and slugs instead of leaves. When the larva is full grown, it forms a pupa that is very much like a small butterfly chrysalis. The adult hatches out, lets its wings expand and harden, and then flies away to flash its signals, mate and repeat the cycle.

Complete metamorphosis

Complete metamorphosis

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A Firefly's Dark Side

A field full of flashing fireflies lighting up a warm summer evening is a beautiful sight, and it makes perfect sense for this special little insect to be given the honor of being a state insect. Many of us, as children, have gone out at the beginning of a June night with a jar, determined to catch a few of these harmless creatures to set beside the bed and watch as we fell asleep. It's an essential part of a middle-America childhood. These scenes are honest and pure; however the Photuris firefly's habits are anything but wholesome.


The Set-Up

The fireflies you see flashing in the dark are typically males, sending out signals as they try to connect with the females, who often remain on the ground and flash in response. When a male firefly makes a love connection, he drifts down to his new mate, following her light signals. Each species has a specific kind of signal, when in hue, brightness, or duration, and this is how the correct species find each other.

Photuris fireflies, however, including P. pensylvanica, don't play this game. In fact, they take advantage of it. The females sit in the grass, but instead of their own signals they send out signals that mimic those of other species. A male firefly sees the signal down below, makes the connection, and flies down to join what he assumes is his new mate. However, when he arrives he finds something else entirely.

The Attack

The hopeful male firefly has been tricked into flying into the arms of an imposter sending a fake message. When he arrive, the Photuris female grabs him with sharp claws and promptly eats him alive. Since she also can't produce the glow-goop fireflies need to make light, she also incorporates all of her victim's.

There's even more to it than that -- check out the awesome video below.

Cool Light

The light organs that give fireflies their name are typically located at the tip of the abdomen. They are very specific to each kind of firefly, and help them identify (or victimize) each other in the field.

Fireflies produce light by mixing oxygen with a pigment called luciferin. This chemical reaction creates a flash of light that generates virtually no heat. Techincally speaking, the enzyme luciferase acts on the luciferin in the presence of magnesium ions, a chemical called adenosine triphosphate (ATP) and oxygen to produce light.

According to some sources, this is the most energy efficient light in the world, since nearly all of the energy from the reaction becomes light.

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30-second exposure of fireflies in the woods.

30-second exposure of fireflies in the woods.


The following sources were used for this guide:

State Symbols

Firefly Facts


This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

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