Abstract

Objective

To determine if cricket chirps can be used to predict the outdoor temperature.

Introduction

Do you love to hear the pulsing chirp of crickets as you fall asleep? It is an unmistakable sound. Some people find the sound pleasing and peaceful. Some think that crickets bring good luck, and keep them as pets in beautifully decorated cages. Other people find the sound loud and annoying, especially if a cricket happens to get inside a home to escape the cold. However you feel about crickets, their chirps hold a surprising message...they can be used to predict the outdoor temperature!

How is this possible? Crickets, like all other insects, are cold-blooded. They take on the temperature of their surroundings. Many characteristics of cold-blooded animals, like the rate at which crickets chirp, or the speed at which ants walk, follow a special equation called the Arrhenius equation (which you can investigate further in the Variations section at the end of the Experimental Procedure). This equation describes the activation energy or threshold energy required to make a chemical reaction occur. For instance, crickets, like other living things, have many chemical reactions going on inside their bodies. As the temperature rises, it becomes easier to reach a certain activation or threshold energy, and chemical reactions, like those that occur during the muscle contractions used to produce chirping, can occur more rapidly. As the temperature falls, the rates of the chemical reactions inside the crickets' bodies slow down, causing characteristics, such as the chirping, to also slow down.

How do crickets make their distinctive chirp? Crickets and other insects can't talk or sing the way humans do. They make sounds in a process called stridulation, where special body parts are rubbed together to make a noise. In crickets, generally only the males make noises, and usually only at night. There is a special structure on the top of their wings, called a scraper. The crickets raise their wings to a 45-degree angle (kind of like raising the lid on a piano to increase its volume) and draw the scraper of one wing across a series of wrinkles on the underside of the other wing, called a file. It's somewhat like running your finger along the teeth of a comb.

As far back as the late 1800's, there have been articles published, noting that the rate, or number of chirps per second that crickets make, changes based on the outdoor temperature. If you want to hear examples of cricket chirps under hot, warm, cool, and cold conditions for yourself, visit these sound recordings of the snowy tree cricket.

There have been many equations published, describing the relationship between the number of chirps per second and the temperature. These equations all vary slightly, depending upon the species of cricket, but the snowy tree cricket is frequently cited as the most accurate at predicting temperature. One of the oldest and easiest-to-use cricket thermometer equations is published in the Farmers' Almanac, a famous book updated each year and used to predict the weather. It says that if you want to get the temperature in degrees Fahrenheit, count the number of chirps over a 14-second time period and then add 40.

Equation 1:

TF

=

N14 + 40

TF is the temperature (in °F). N14 is the number of chirps in 14 seconds (sec).

To get the temperature in degrees Celsius, the Farmers' Almanac says to count the number of chirps in 25 seconds, divide by 3, then add 4.

Equation 2:

TC is the temperature (in °C). N25 is the number of chirps in 25 seconds (sec).

These equations are good only in the range of temperatures from 55–100 degrees Fahrenheit. Outside that range, the crickets find it too cold or too hot to sing!

So, now it's time to put your little cricket friends to the test! Grab a stopwatch and a thermometer this evening and see how accurate your neighborhood crickets are at answering the universal question, "What is the temperature?"

Terms, Concepts, and Questions to Start Background Research

• Cold-blooded
• Arrhenius equation
• Activation energy
• Threshold energy
• Stridulation
• Scraper
• File
• Exponential factor

Questions

• Why is it possible to use crickets to predict the temperature?
• How do crickets make their chirping sound?

Bibliography

This source provides sound recordings of snowy tree crickets:

• Walker, T. (1962). Snowy Tree Cricket, Oecanthus fultoni. Retrieved March 4, 2010, from http://entnemdept.ufl.edu/Walker/buzz/585a.htm

This source provides photos and general information about field crickets:

• Mason, J. (2008, July 31). Field Cricket. Retrieved September 2, 2008, from the Great Plains Nature Center website: http://www.gpnc.org/field1.htm

These sources provide information on the Arrhenius equation:

• Clark, J. (2002). Rate constants and the Arrhenius equation. Retrieved December 8, 2008, from http://www.chemguide.co.uk/physical/basicrates/arrhenius.htm
• Shodor. (2008). The Arrhenius Equation. Retrieved December 8, 2008, from http://www.shodor.org/UNChem/advanced/kin/arrhenius.htm

Materials and Equipment

• Stopwatch
• Helper
• Multiple evenings with a temperature range between 55°F and 100°F
• Access to an area with crickets, or purchase a cricket from a pet store
• Outdoor thermometer
• Lab notebook

Experimental Procedure

Collecting Your Data

1. On an evening when you hear crickets singing, go outside with your helper, lab notebook, pen, stopwatch, and thermometer.
2. Have the helper say, "Go," and start the stopwatch, while you count the number of cricket chirps.
3. When the helper says, "Stop" at the end of 14 sec, stop counting cricket chirps and write down your count in a data table, like the one below, in your lab notebook.
   1. Note: If you are doing your experiment in degrees Celsius, rather than in degrees Fahrenheit, count the number of cricket chirps for 25 sec and modify your data table according to Equation 2 in the Introduction.
4. Repeat steps 1-3 at least two more times.
5. Take a temperature measurement with your thermometer and write down your measurement in your data table.

   Evening	Count 1	Count 2	Count 3	Average of Counts	Actual, Measured Temperature (°F)	Temperature Based on Cricket Chirps (°F)
   1
   2
   3
   4

6. Repeat steps 1-5 on at least three more evenings. Try to take your measurements during evenings with different temperatures.

Analyzing Your Data

1. Average the number of counts for each evening and record your average in your data table.
2. Using Equation 1 or Equation 2, calculate the outdoor temperature, based on the number of cricket chirps, and record your calculation in your data table.
3. Plot the average number of chirps in 14 sec (or 25 sec if you are doing your experiment in degrees Celsius) on the x-axis, and the calculated and measured temperatures on the y-axis. Did the Farmers' Almanac equation accurately predict the measured temperature? Were there certain temperature ranges over which it did a better job than others?

Variations

• Compare which gives the best fit to your calculated temperature data: The linear Famers' Almanac equation (Equation 1 or Equation 2) or the Arrhenius equation, which contains an exponential factor. Information on the Arrhenius equation can be found in the Bibliography, above.
• Compare the chirps of different species of crickets, or different insects altogether, such as katydids, to see which makes the best "insect thermometer."
• Compare cricket chirps at different times of the year or in different geographic locations to see if there is a seasonal or geographic affect on temperature accuracy.

• For more science project ideas in this area of science, see Zoology Project Ideas.

Credits

Kristin Strong, Science Buddies

This science fair project was inspired by retired teacher Jeri Malouf, Director of Morningside School, Logan, Utah.

Last edit date: 2008-12-04 10:00:00