The Milkweed Bug Project:
An Experiment in Factors Influencing the Rate of Metamorphosis
developed by Maya Merritt
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State Objectives |
Competency Goal 1: The
learner will develop abilities necessary to do and understand scientific
inquiry. |
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Time Required |
two 50 minute class periods. Day 1 – set up experiment Day 2 – analyze data and discuss * a short amount of time
will be needed to record insect growth every other day. In total, expect that 1-2 months may pass
until metamorphosis is complete. |
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Note to Teachers |
The variable in this
experiment is 0.5% sugar solution vs. water.
Students may choose any liquid as their variable, including soft
drinks or juices. |
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Resource for Live Arthropods |
Milkweed Bugs: |
Observation: The following experiment is based on observations that the rate of insect metamorphosis can be affected by outside environmental factors.
Hypothesis: Milkweed bugs developing with access to 0.5% sugar water solution will complete metamorphosis faster than those developing with access to only tap water.
Experimentation
Procedure:
Materials:
6 milkweed bugs
3 small Petri dishes
3 pieces of modeling clay
6 rubber bands
3 micro centrifuge tubes with the tops cut off
6 unsalted sunflower seeds
3 small pieces of cotton
ruler
dissection scope useful, but not necessary
1. Place two sunflower seeds in each dish.
a. Fill the micro centrifuge with water for two of the dishes. Soak the cotton in water and use to plug the end of the centrifuge tube. Place in a Petri dish using a piece of modeling clay to secure. Label one dish C for control. The other is for extra bugs in case of fatalities.
b. In the third dish, everything else will be the same except add 0.5% sugar water instead of tap water. To make 0.5% sugar water solution, weigh out 0.5 grams of sugar and place into 100 ml of tap water. Shake to dissolve and add to the micro centrifuge. Label this dish E for experimental.
2. Add 2 milkweed bugs to each Petri dish and rubber band shut with two rubber bands.
3. Make observations every other day looking for evidence of growth including size and/or apparent molts. A dissecting scope may help in this.
4. Keep and eye on both the level of water in the micro centrifuge as well as whether or not the cotton plugs appear to be getting moldy. Replace both as needed.
Data Collection: Examine the milkweed bugs every other day until all have gone through 5 molts apiece. This may take close to two months. Remove each molt as you record it as that will make it easier to see future molts. Have students develop a data table to record this data.