Firefly Questions


(But Were Afraid to Ask)

Fireflies are fascinating creatures—and we get a lot of questions about them. So many that we thought we’d publish the most common questions we get and their answers here. Read below to
find the answers to everything you were most likely wondering about fireflies.

Where can I buy live fireflies?

You can’t. Firefly populations are crashing in many areas, and they are also fragile and don’t survive well on long-distance trips. It is generally not advisable to transport live fireflies
between states or other far distances, as this can disrupt the natural habitats where the fireflies live.

Can I get paid to collect fireflies?

Fireflies produce a chemical called luciferase or luciferin in producing light. This chemical is used for food safety testing and biomedical research, and is in high demand in the biochemical
industry—it can be bought in desiccated or powdered form from chemical companies. These companies used to pay people to collect fireflies to harvest the chemical for research purposes. It is now
possible to produce luciferase / luciferin synthetically, but some companies—including The Firefly Project in Tennessee—still pay people to collect and send in fireflies. The Firefly Project pays
about $12 per ounce for live fireflies as of this writing, or $12 per approximately 600 fireflies.

This is a dangerous practice for firefly populations. Harvesting the chemical results in the death of the fireflies—an inhumane practice and a senseless one, since luciferase / luciferin
can now be produced synthetically. It is also damaging to native firefly populations, which are in trouble across the country due to habitat destruction, pesticides, pollution, and other reasons.

Do firefly eggs glow?

They sure do! Firefly eggs are bioluminescent, and the larvae will flash inside the eggs in response to vibration.

Why do fireflies flash?

While most scientists agree that fireflies flash their lights to each other as a mating signal, many species of fireflies are actually capable of lighting up throughout their lifecycle—not just
during mating. Some fireflies (and their larvae) light up to warn off predators—fireflies actually produce a chemical that tastes bad to most predators. They also use their lights to identify others
of the same species, and to tell male from female. Studies indicate that female fireflies use the flash patterns emitted by males to choose their mates—the higher the flash rate and intensity, the
more attractive a male firefly will be to a female.

What months are you most likely to see fireflies?

It depends on where you are. Fireflies are found on five continents throughout the world, and can appear at different times of year depending on the local climate. They tend to like warm,
fairly wet weather. In the United States, they tend to appear in May, June or July. Some warmer areas of the U.S. like Texas have "late" season fireflies and you can expect to see them all the way into October and November if the conditons are right.

How can fireflies save lives?

Luciferase and luciferin, the chemicals fireflies produce to generate their light, is useful in biomedical research. It is primarily used in food safety testing, but it has also been used to
study cancer and diabetes, allergy response, cpr & first aid certification, gastric inflammation, and the harmful effects of various pollutants on the human body. Fortunately, the chemicals can now be produced synthetically, so live fireflies are not generally needed to produce it for biomedical research.

What do fireflies eat?

Firefly larvae are generally carnivorous and eat worms, snails, and other small, soft-bodied creatures. However, interestingly enough, scientists aren’t sure what many species of adult fireflies eat.
An exception is the genus photuris, a firefly that closely mimics the flash pattern of the female photinus—another, closely related firefly genus—in order to capture and eat the males of that genus.

It is possible that adult species of fireflies eat pollen and nectar from plants, other species of bugs, or possibly nothing at all—as their adult lifespans are short.

Do bats eat fireflies?

Possibly, but fireflies are not generally part of their diet. More research needs to be done on this and the affect bat predation has had on the evolution of firefly signaling behavior. Some species have been documented eating fireflies (Lloyd 1989) and others such as gray bats have been observed catching a firefly with it’s mouth but then immediately dropping it. They were observed doing this more than once. (personal comm. from Merlin Tuttle).

Fireflies are poisonous or distasteful to most bat species. Part of the reason for this is the steriod like compounds called lucibufagins and betaine that make them poisionous. Some fireflies such as Photuris sp. do not contain significant quantities of lucibufagins, making them possibly more likely to be eaten. Several studies have been conducted to test whether bats will eat fireflies by using mealworms dusted in lucibufagins from ground up fireflies. Bats will reject them each time they are feed. While this does show bats will reject these chemicals, the study itself is not reputable as force feeding bats has been shown to not reflect what they might actually do in the wild. For this reason, these study results are not reliable.