Utilizing the June Beetle
to Introduce Problem Solving  

 

AUTHORS: Michael Surma, Mike Virlee, Lois Wisniewski

SUBJECT: Biology, Environmental Studies

GRADE LEVEL: High School

SUMMARY:

Fall is the time to be scouting lawns for white grubs. The timeliness of the June Beetle (Phyllophaga sp.) life cycle lends itself well to the opening days of the school year. Those teachers searching for an interesting opening activity in their science classroom may want to consider utilizing the white grub activity in an attempt to fulfill the following objectives: utilization of the scientific method (experimental design and data analysis), active involvement of parents in the data collection process, and the utilization of peer editing.

Students are familiar with the June Beetle as the organism that flies into screens and around outdoor lighting during the early summer months. These adult beetles typically lay their eggs (50-100) between July 10-15 (Central Illinois). The eggs then hatch (10-21 days) into the larval (grub) stage. The white grub is presently found in typical Illinois lawns, feeding on grass roots. The grub itself is a 'C' shaped larvae, white in color, with a brown head.

Biology II students (Juniors/Seniors) are given the information provided in the preceding paragraph. They are then asked to formulate hypotheses that will address the problem: Where do female June Beetles prefer to lay their eggs? At the onset of this assignment students have a difficult time listing all of the potential variables that may impact the beetle's egg laying decision. Once they start to look at the potential microenvironmental factors present in a typical lawn, students are then capable of choosing the one variable that they feel will impact the 'decision' to the greatest degree.

Once students have selected the variable to be tested, they are required to design an experiment with numerical and concise instructions that could be deemed repeatable by other scientists. It is not uncommon for students to forget that they can no longer work with the organism in the adult stages. Many first drafts are not reflective of the idea that the grubs are the only stage available for data collection at this time of year. After arriving at this realization, students are then left with the task of determining where the grubs would be located. Questioning revolving around the available food source of the grubs leads students to recognize that the grubs will more than likely be located within the first 10-15 centimeters of soil. At this point students are reminded that any procedures utilized should be minimally intrusive to the test area (students' lawns). The students must then determine the instructions that would allow them access to the grass roots and feeding grub numbers without disrupting the environment.

After students design their experiment, peers edit the experimental procedures for clarity. Students are then given hypothetical data from a typical lawn. The data gives information regarding test plots and grub number counts. Students are then asked to analyze the data presented and to locate any patterns in the numbers found as they correspond to certain environmental conditions. Students are also asked to place parenthesis in areas where they would require additional information before drawing any conclusion.

After analyzing the hypothetical data presented, students are given the following additional information on grubs: Females prefer lush, green grass with moist soil (frequently watered areas surrounding gardens etc.). The beetles are also attracted to the warmer areas of the lawn adjacent to sun, heated concrete, or asphalt driveways. Fewer eggs are laid in the cooler areas of the lawn, under trees or in areas exposed to night lighting. Additionally, if the grub count is higher than 10-12 per 30cm2 area, then treatment is recommended. (See article addition to the Bloomington, Illinois newspaper, The Pantagraph, Sunday, August 20, 1989. "Late summer time to scout for white grub," by Peg Balbach.)

Students are then asked to determine if the lawns in the hypothetical example should be treated. They are additionally asked to explain proper treatment procedures and the effect of treatment on other living organisms. Students are also responsible for understanding the life cycle of the June Beetle. After completing the preliminary experimental design and learning enough background information on testing procedures etc., the upperclassmen become lead researchers for a team of freshmen who have also been learning about the scientific method. Students collaboratively design experiments that would determine if treatment for White Grubs was necessary in their lawns. Actual experimentation and data collection take place at this phase of the project. (For additional details, see article "Problem Solving, Peer Teaching and June Beetles")

 

FOR FURTHER INFORMATION, PLEASE CONTACT:

Michael Surma  Mike Virlee mvirlee@ilstu.edu Lois Wisniewski University High School 7100 Illinois State University Normal, IL 61790-7100 ph 309 438-8448 fax 309 438-5198
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