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Larval Taste Test How you might conduct a taste-test, to see what monarch larvae prefer to eat? Here are research ideas from students in CT, PA and from biologist Dr. Bill Calvert: From Rocky Hill, CT Title: What's for dinner? Problem: What plants do Monarch larvae prefer? Hypothesis: We believe they will prefer milkweed. Materials: gift box 10x12, fresh milkweed leaves, fresh maple leaves, fresh oak leaves and fresh iceberg lettuce leaves. Procedures: Place the fresh leaves at separate corners of the box. Place ten larvae in the middle of the box wait 30 minutes and count # of larvae at each set of leaves. Repeat every hour for the next 3 hours. Collect data from your observations to see which leaves attracted more larvae and draw a conclusion. You may also repeat the next day. Jendayi and Courtney of Griswold Middle School (northgms@aol.com) From Munhall, PA We have designed and performed a taste test for larvae in which we place them equidistant from leaves of two different species of milkweed. We discovered that they go to and begin eating which ever leaf they were hatched upon and which they 'took their first bite'. So our conclusion is that the leaf that they begin life on is the leave that they prefer. Someone may wish to work with very, very small larvae to see if this preference holds true immediately upon hatching. McKeesport Area Homeschoolers (education_02@email.msn.com) From Dr. Calvert "It's easy to set up a simple experiment. Place four squares of different hosts and a non-host (this makes the results very dramatic) in a cottage cheese container. Fasten them in a ring with sewing pins. Place a larva in the center of the arena. Wait until half the material is eaten, then score the remaining leaf disks/squares as to how much has been eaten. Compare the various plant species in the test. (Unfortunately I have not been able to discern much difference in preference among milkweed species by monarch larvae.) "One of the features of this kind of experiment is that kids can come up with their own hypothesis. For example they might decide that it is the milky quality of the plants that attracts the monarch larvae. So a test of dandelion, morning glory and maybe a Euphorb against a milkweed would be a good test. The results would be dramatic."
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