University of Minnesota

How Does Climate Affect the Emerging Rate of Pupae?

Ricky Lopez
McGuire Jr. High School
Lakeville, MN


The purpose of the experiment was to find out how the climate, or the weather over a long period of time would affect the emerging rate of pupae. I attached one pupae to each of my three boxes. I put one in the refrigerator, one in room temperature, and one in the heat pad box. The pupa in the refrigerator/cold climate took 33 days to emerge. The pupa in room temperature took 8 days to emerge. The one in the heat pad box took only 4 days. There were a few uncertainties, like the refrigerator door was left open overnight and the heat box with the heat pad was also left open. I did a test on how climate affects the emerging rate of a pupa. My hypothesis was correct, the pupa in the heat pad box took the shortest amount of time to emerge.


Will the climate affect the pupae emerging rate and if so, how? Do pupae take longer in the cold, or does it take longer in the warmth of summer? Will the pupae die in the cold? Or perhaps will the heat pad be to much for the pupae? Is room temperature the best bet for the pupae, or not? This is what I would like to discover in this experiment.


The butterfly will emerge faster in the warm box rather than room temperature. Warmer weather is the butterfly’s climate. The test in room temperature will be the control. In the refrigerator, the pupa will die because this is not the pupa’s natural climate. As many know, butterflies are cold-blooded animals. The pupa will definitely take longer, if not die, in the refrigerator because it will be too cold for a cold-blooded animal.

Background Information

The egg stage lasts for four to ten days, depending on the temperature. The monarchs migrate because they cannot live through Minnesota winters. When winter comes, most animals will gain body fat and get more fur. Butterflies that emerge in colder weather are smaller than the ones that are born in warmer weather. The butterflies’ scales become darker. They become slower. It takes most butterflies three months to migrate. The butterflies have many stages of life so for the most part they are right on time to go to Mexico. In the spring, there are butterflies that live for only twenty days. Their purpose is to lay eggs that become the next butterflies which can live up to eight months.


  1. heat pad
  2. refrigerator space
  3. room space
  4. three Rubbermaid plastic boxes
  5. three pupae
  6. three thermometers
  7. Juicy Juice (For adults)


  1. Same size boxes.
  2. All pupae kept track of, we can then see the results more clearly.
  3. Temperature stays the same in each experiment.
  4. All are in mostly darkness.
  5. The temperature is controlled in each situation.

Dependent and Independent Variables

Dependent Variables

  1. The emerging rate
  2. The size of the pupa before becoming a pupa

Independent Variables

  1. Temperature
  2. Amount of swinging in the box


  1. Collect three plastic boxes, three pupae, three four- inch pieces of thread, three pieces of clay, one cardboard box, and one refrigerator.
  2. Label three plastic boxes with your name.
  3. Put one box in the refrigerator, one under the cardboard box with the heat pad, and one in the room temperature spot
  4. For each of the three pupae, tie the four-inch piece of thread into the cremaster.
  5. Connect a small amount of clay to each piece of thread.
  6. Put one pupa in each of the plastic boxes by connecting clay to the lid of the box.
  7. Check on the pupa every day to see if it has emerged.
  8. Record results in data chart form.


(Photo: Ricky Lopez)

In this experiment, I started out with a plan. I collected three boxes, pupae, pieces of clay, and three pieces of four-inch thread. I labeled the boxes with my name so that I would not get confused with other people’s experiments. I put a box in the refrigerator, a box in the heat pad box, and a box in room temperature. I let them sit in their spots for one day so that they could get to their respective temperatures. Then I tied pupae in the boxes and put the boxes in their spots. I checked the boxes everyday to see if they had emerged or not. I did this experiment to see if the climate/temperature would affect the emerging rate of the pupae.

In the experiment, my hypothesis was proven correct, in the box with the heat pad, the pupa took only four days to emerge. In room temperature, it took eight. In the refrigerator, however, it took thirty-three days for the pupa to emerge from its chrysalis. The only thing that was left was the cremaster and its webbing.

There were two things that may have affected the emerging rate of the pupa. A couple of days in a row, we noticed that the refrigerator door was left open, this may have heated up the refrigerator overnight, thus creating different results. Also, there was an odd smell in the refrigerator, it could have been the rat food, but it also could have been the other pupae in the refrigerator. This could have affected the emerging rate because the odor may have posed a threat to the butterfly.

My next question is why would the butterfly sense the cold, and not emerge because of the cold? I guess if I had another chance to do this experiment, I would make sure that I recorded my results right away. I would put many pupae in each test, to help me see the results more clearly.

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