Botany Butterfly Farming Gardening Horticulture Monarch (Danaus plexippus) Queen (Danaus gilippus)

DIY Guide: How to Test Milkweed Plants for O.E. Using a 40X Student-Grade Microscope

Step 5: Examine Under the Microscope

  1. Place the slide under the microscope.
  2. Adjust the microscope to the 40X magnification setting. 100X is better, if available.
  3. Focus the microscope until the leaf material becomes clear.
  4. Scan the slide slowly, looking for O.E. spores, which will appear as small, oval, and darkly colored objects, much like American footballs.
40X view of Monarch butterfly scales, larger, with the dust like O.E. spores. The inset photo shows O.E. spores at 100X.
Photo of clean Monarch Butterfly scales; no O.E. present. A clean Milkweed leaf may present nothing to observe.

Step 6: Record Observations

  1. Keep a notebook handy to jot down what you see.
  2. If possible, capture images through the microscope for documentation.
  3. Note the density and distribution of the spores, if present.

Step 7: Dispose of the Sample

  1. Once done, carefully remove the slide from the microscope stage.
  2. Dispose of the tape and slide in a proper waste container.

Step 8: Clean Up

  1. Turn off the microscope and cover it.
  2. Dispose of your gloves.
  3. Clean your workspace.


Testing for O.E. spores on milkweed leaves is crucial for understanding the health of your local Monarch and Queen butterfly populations. Although a 40X student-grade microscope may not offer the highest resolution, it is sufficient for a basic O.E. test. This DIY guide makes the process simple enough for anyone to carry out, contributing to citizen science and the conservation of these beautiful creatures… one day at a time!

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