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Butterfly Hunt

The Role of Density Dependence in Batesian and Müllerian Mimicry


Mayra C. Vidal
Department of Biological Sciences
University of Denver
Kylee Grenis

Tri-County Health Department
Whitley R. Lehto
Department of Biological Sciences
University of Denver
Robin M. Tinghitella
Department of Biological Sciences
University of Denver
Shannon M. Murphy
Department of Biological Sciences
University of Denver


This case study uses an interactive activity to illustrate density dependence in ecology classes. We developed a "hunt" using paper butterflies with warning signals on the upper side of the wings and symbols that indicate if a butterfly is noxious underneath the wings. Butterflies are distributed in four different patches with varying densities of noxious and palatable butterflies, simulating Batesian or Müllerian mimicry. Students can catch as many butterflies they want for a period of time, but if they catch more than three noxious butterflies they are out of the game. After the activity, students calculate the survival rate of each type of butterfly in each patch and discuss the implications of density and warning signals according to their results. Students then answer questions and build graphs using the data from the activity and knowledge from the class and the discussion. With this case study, students will be able to understand negative and positive density dependence, as well as predation, learning, and convergent evolution, while recalling or being introduced to Batesian and Müllerian mimicry.


  • Review numerical and functional responses.
  • Build graphs.
  • Define Batesian and Müllerian mimicry.
  • Explain and distinguish between negative and positive density dependence.
  • Discuss convergent evolution and learning.
  • Describe how predation can lead to convergent evolution in warning signals.


density dependence; mimicry; predation; aposematism; warning coloration; numerical response; functional response; fitness; convergent evolution; butterfly;

Topical Areas


Educational Level

High school, Undergraduate lower division, Undergraduate upper division


PDF, PowerPoint

Type / Methods

Demonstration, Directed, Discussion



Subject Headings

Ecology  |   Biology (General)  |   Evolutionary Biology  |  

Date Posted


Teaching Notes

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Teaching notes are intended to help teachers select and adopt a case. They typically include a summary of the case, teaching objectives, information about the intended audience, details about how the case may be taught, and a list of references and resources.

Supplemental Materials

The PDF flie below contains "butterflies" for the hunt; the teaching notes explain how many to print out. The PowerPoint presentation below is used to structure the class discussion and to record results of the hunt.

  Butterflies (butterfly_hunt_sup.pdf)
  PPT Presentation (butterfly_hunt_sup.pptx)

Answer Key

Answer keys for the cases in our collection are password-protected and access to them is limited to paid subscribed instructors. To become a paid subscriber, begin the process by registering.


Kathryn Swanson
Concordia - St. Paul
St. Paul, MN
Overall, I liked this activity, but my students quickly recognized the difference between noxious wings (solid black ovals) and palatable mimics wings (solid black ovals ringed with gray). This made the results for patch A and patch B almost identical since after the students “ate” the regular butterflies they systematically ate all the palatable mimics.


Authors’ Reply:

A couple of factors may influence the results experienced in class.

1. It is possible that there are differences across printers that make the difference between models and mimics more obvious. So an instructor might have to adjust contrast between black and gray when printing to account for differences among printers.

2. An instructor can also shorten the time given for the hunt. In class this year we ran the activity by giving the students only a minute to “hunt.” Teachers can also observe how quickly students are over-harvesting their patches and end the hunt at any time if students are hunting too quickly.

We hope these suggestions are helpful for future instructors.