University of Minnesota

How Many Male and Female Butterflies Came Out of Their Chrysalises Each Day?

Jason Blank, Grade 6
Plymouth Middle School, Robbinsdale School District 281
Plymouth, MN


I wanted to find out if there was a pattern to when males and females came out of the chrysalis. I would like to have had data from all of the monarchs. Some monarchs emerged on the weekend and we didn't know which ones they were. We found that this year, there were more females emerging on most days than males.


I think that in one out of four days, more males will be born than females.


  1. monarch butterflies
  2. data charts and log book


  1. Record the number and sex of butterflies born each day.
  2. Keep this information in a log.
  3. Find the average number of males and females emerging each day.
  4. Create graphs to analyze this information.


  1. We had days when more female than male monarchs emerged.
  2. The number of females emerging in any one day ranged from 0 to 16.
  3. The number of males emerging in any one day ranged from 1 to 10.
  4. The average number of females born daily was 6 and the average number of males born daily was 5.
(Photo: Jason Blank)


The average number of female butterflies emerging daily was greater than the number of male butterflies on most days. We had more females than males emerge this year.

What I Would Do Differently

I would analyze the butterflies emerging daily from other years and find out if it is the same. Last year there were more males than females. I would also like to compare the time of year and the average number of females or males that emerged.

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