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Are fireflies disappearing? People across the country are joining a research project to find out.

Catching fireflies is one of the best parts of summer for Oscar Harris, an 11-year-old from Baltimore, Maryland. Sometimes he puts the fireflies into a jar and watches them flicker on and off. Then he releases them.

If fireflies were to disappear, Oscar would feel like a big part of his summer was missing too. "I wouldn't like it at all," he says. "I'd lose something I like doing."

In some parts of the country, people aren't seeing fireflies as often as before. Could fireflies be disappearing? A group of scientists is on the case. And they're hoping ordinary people--not just experts--will help them solve the puzzle.

Glow Makers

Firefly light is a type of bioluminescence (bye-oh-loom-in-ESS-ens). The word comes from the combination of two Greek words that mean "living light."

In addition to fireflies some other animals, bacteria, and even mushrooms have the ability to glow.

Like other glowing creatures, a firefly makes light by mixing chemicals together in a part of its body called the lantern (see How a Firefly Lights Up, above). The exact color of the light depends on the species. The glow can be yellow, green, or orange.

Living things produce light for many reasons. Some use it to attract prey. Others might try to startle a predator with a flash. For fireflies, which are actually a type of beetle, light shows are all about love.

Dazzling Dates

Fireflies' light displays are an insect version of dating, says Christopher Cratsley. He's a firefly researcher at Fitchburg State University in Massachusetts.

Male fireflies blink on and off as they fly around. They're trying to dazzle potential mates with their lights. A female usually waits on a blade of grass or a bush until she sees a flicker she likes from her own species. When that happens, she answers with her own blinking light.

Adult fireflies have just a short time to find mates before they die. These insects have full lives before this stage of their life cycle. Before becoming adults, firefly larvae (LAR-vee) spend up to two years creeping around underground. They feast on animals such as worms and grubs that live in the soil. In springtime, they transform into the blinking beetles you see on summer nights.

Shining Brightly

With limited time as adults, firefly flashes are very important, says Cratsley. Without them, fireflies wouldn't attract mates. Without mates, no new generations of fireflies would be born.

"Fireflies' lights are their only way of finding each other," Cratsley says (see Firefly Flash Patterns, below).

Streetlights and porch lights can make life tough for these beetles. The bright lights can make it hard for fireflies to see each other's flickers. As a result, males and females of the same species can't easily find each other.

Gone in a Rash?

Every year, Cratsley hears more stories from people who say they have stopped seeing fireflies in their area. But until scientists know how many fireflies flicker in the same places each year, they won't know for sure if the insects' numbers are falling. That's where the Firefly Watch program comes in. It's based at the Museum of Science in Boston, Massachusetts.

For four years, Firefly Watch has signed up people across the country to count fireflies in their backyards. During firefly season (usually May to September), volunteers count the fireflies they see during 10 minutes one night a week. Scientists use the information to study firefly populations. Over time, they'll be able to see if the numbers are changing.

Volunteers also report other things that might affect fireflies, such as how often they cut the grass or if there is a streetlight nearby.

"Over several years, the data can tell us whether fireflies are really disappearing or whether people's stories are just stories," program director Don Salvatore says.

words to know

bioluminescence--an organism's ability to give off light through chemical reactions inside its body

bacteria--living things made up of single cells

life cycle--the series of changes, or stages, in the life of a plant or an animal

larvae--animals in an early stage of development that look very different from their adult stage

population--a group of animals or plants of the same species living in one place.

Firefly Flash Patterns

Not all of the 200 species of fireflies light up. But each one that does has its own flash pattern. With a unique set of blinks, a firefly can tell if another firefly is a member of its species. Males flash their patterns first, then females respond.

(1) Photinus pyralis

(2) Photinus marginellus

(3) Photinus consimilis

(4) Photinus granulatus

(5) Photinus collustrans

Find Your Match

Can you find a match to your own "species" using only your ears?

(hands-on science)

Observe: In the wild, animals have to be able to find members of their species among many others. Fireflies use blinking lights to do this.

Ask a Research Question: How can you use your senses to find other members of your species?

Form a Hypothesis Based on This Question: Using your ears, what clues can you use to find others of your species?

Materials: colored plastic cups (one per student) * assorted small objects (paper clips, pennies, popcorn kernels, dried pasta pieces, dried beans, etc.) * markers (one per student) * aluminum foil * rubber bands (one per student) * large bag


1. Divide the cups into pairs.

2. Place the same objects inside each pair of cups. Put three or four objects in each cup. For example, fill two cups with three pennies each, fill two cups with three beans each, etc.

3. Label the bottom of each cup with the name of the object it contains. (You can use P for penny, PK for popcorn kernel, and so on.)

4. Cover each cup with foil. Secure it with a rubber band.

5. Carefully place the cups in the large bag.

6. Your teacher will bring the bag around the room. Take one cup from the bag. Don't look inside the cup or peek at the bottom.

7. Walk around the room shaking your cup. Listen to other students' cups. When you hear a sound that matches yours, sit next to your match.

Record Results: Were you able to find a cup that made the same sound as yours? Were some sounds easier to match than others? Record your experiences.


1. How is this experiment similar to how an animal finds a mate? How is it different?

2. If you had to do this experiment on a noisy city street, how might the results change? How is this similar to the challenges fireflies face?


1. The experiment is similar to how animals find mates because animals have to rely on their senses to identify others of their own species. Sometimes this is done by particular calls (sounds). The experiment differs from what animals do in the wild because animals use a variety of signals to find members of their species, including scents, lights, and body language.

2. if this experiment were done on a noisy street, you might have had trouble hearing your match's sounds among the louder sounds around you. This is similar to a firefly's difficulty with seeing a potential mate's flashes in brightly lit areas.

Find Out More

To learn more or to join the Firefly Watch, go to



Lexile Level 890; Guided Reading Level S


Understand how and why researchers are studying the characteristics and populations of fireflies.


Depending on the size of yotlr class, buy one to two big bags of "fun-sized" regular M&M's (each contains 21 mini bags). (Math in the plan below uses two big bags.)


1. Tell students you have 42 mini bags of M&M's. Their assignment is to figure out the total number of M&M's you have by using only 4 mini bags.

2. Put students into groups of four and hand out one bag of M&M's to each person. Give students 5 to 10 minutes to brainstorm a method for calculating the total number of M&M's you have and to do the calculation.

3. Ask students to share the number they came up with. The method of counting a small sample and extrapolating the number to a larger population is called sampling. Students should have calculated the average amount of M&M's in their four packs and multiplied by 42.


* How and why do Firefly Watch researchers use a sampling method to count fireflies? (How: They use the data from volunteers who count fireflies for i0 minutes one night per week. Why: It's impossible to count each firefly every day. Sampling provides an educated guess.)


* Night Fairies Series #2: Levi the Firefly Fairy by Daisy Meadows (Scholastic, 2011)

* For more on the Firefly Watch, visit: /fireflywatch
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Title Annotation:life science
Author:Brownlee, Christen
Geographic Code:1USA
Date:Sep 1, 2012
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