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Predator-Prey Column

I would like to start by thanking Dan Lauffer and the University of Wisconsin – Madison Fast Plants and Bottle Biology for giving me permission to print these instructions for creating the Predator-Prey Column.

    Materials you will need:

    • two 2-liter soda bottles
    • one soda bottle cap
    • Bottle Biology tool kit *
    • one to three film cans
    • water feeder *
    • Distilled water (if using carnivorous plants)
    • soil, twigs, small plants
    • The prey: fruit flies (also available at a lab supply company)
    • The predator: Praying mantises, spiders or carnivorous plants


    1. Remove labels (using blow dryer) and bases (if they have separate bases) from two 2-liter bottles.

    2. Cut bottle #1 2 cm above the shoulder curve, leaving a tapered end on cylinder A. Cut 1 cm below the hip curve, leaving another tapered end on cylinder A.



    3. Cut second bottle 0.5 cm below the shoulder curve, leaving a straight end on piece B. Cut bottom off 6 cm above hip curve, leaving a straight side on piece C. Poke a 3 to 4 cm hole in cap and put on piece B. An awl or hot nail works well for this.




    4. Slide piece B into cylinder A (you may need to work B back and forth to push it all the way in). Set A and B into bottle base D. If you don’t have a separate base, use the lower 9-10 cm from a footed bottle. Poke air holes. Insert water feeder.

    5. Soil, plants and insects will go into the top chamber A, and the film cans of fruit in the base D below.




    Hot Links

    You can find more Bottle Biology Projects and ideas at:

    University of Wisconsin, Madison-Fast Plants

    Supplies and live insects can be found at:

    Carolina Biological Supply Company

    Bio Quip Entomological Supplies


    * Tool Kit

    • Box top or drawer to stabilize bottle while cutting lines
    • Wax pencil, marker or crayon for drawing cutting lines
    • Razor in safety holder or sharp pocket knife to start cut
    • Scissors to cut bottle
    • “Poke”, darning needle, or diaper pin to make air holes
    • Awl to make holes in bottle caps and film cans
    • Tapered reamer for enlarging holes
    • Paper punch for making large holes in thin plastic
    • Clear waterproof postal or bookbinding tape to join columns
    • Silicone sealant to waterproof joints


    * Water Feeder

    You can make the water feeder out of any small plastic container. Those that work best include small candy containers like the type that hold breath mints, syringe holders (free from veterinarians) and plastic microcentrifuge tubes (cheap from lab supply companies).

    For the wick, cut a short piece of cotton twine, a strip of a utility wipe or a strip of fabric interfacing available from fabric shops. You should first wash the interfacing and utility wipes to remove detergents, flame retardants and other substances. Wet this wick with water and then insert it into the plastic container you are using for a feeder. If you use a microcentrifuge tube or syringe holder, cut off the very tip, insert the wick, and then place the tube into a hole poked in the top of your Predator-Prey Column. Otherwise, attach the container to the column with a rubber band or a piece of tape, and feed the wick through a small hole in the side of the column, so the space around the container or wick isn’t so big that the fruit flies or other column contents can escape. Keep the water feeder full of water at all times!