The return of monarchs to their northern breeding grounds is closely tied to the emergence of their larval hostplants, members of the milkweed family. Milkweeds are perennial plants with very long taproots, and once the new plants poke through the ground, the stored nutrients in their taproots allow them to grow quickly. During most years, monarchs appear very shortly after milkweed emerges, but in some years monarchs get to an area before or several days after there is milkweed. If you know a location that contained milkweed last fall, it is very likely that it will be there again in the spring. Monitoring the appearance, growth, and condition of these important plants will help to reinforce the close connections between monarchs and their environment. Don’t be discouraged if the milkweed seems slow in coming; it usually appears after many other perennials, but should come up eventually if the area hasn’t been disturbed.

For information on milkweed, you can use the section on this topic in the Monarch Biology section, the Monarch Watch website (http://www.MonarchWatch.org), or plant field guides.

• Site where you have seen milkweed in the past
• Milkweed Monitoring Data Sheet (student handout page: one for the entire class, or for individual students who are doing the monitoring)
• Ruler
• Insect field guide

1. Watch for milkweed plants where you saw them last fall. Choose several new plants to monitor, and use sticks or flagging to mark them. You may want to choose a few sites to monitor, and compare growth rates in different locations.
2. Data from 2 plants can be recorded on each data sheet. Record the date that you see the first sign of each new plant.
3. At regular intervals (every 2-5 days) record the height and number of leaves on your plants.
4. Look for insects or spiders on the plant, and any sign of damage. Use a field guide to identify the insects that you observe on the milkweed, and record your observations on the data sheet.
5. Use the data to graph growth over time. You could graph height, or estimate the area of leaf material on each plant each time you observe it. If you are keeping track of spring weather conditions, relate milkweed growth to temperature, rainfall, and cloud cover.
6. Send your data and comments to us at:

Karen Oberhauser
University of Minnesota
Department of Fisheries and Wildlife 200 Hodson Hall, 1980 Folwell Ave.
St. Paul, MN 55108

• Milkweed Monitoring Data Sheet

ã 2001 Monarchs in the Classroom  - University of Minnesota
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