University of Minnesota

Section 3b: MLMP Activities - Site Description and Measuring Milkweed Density

This is the sixth video of the Monarch Larva Monitoring Project video training series, reviewing the initial activities of monitoring: site description and milkweed density measurements.

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Related Activities

Photo Credits (in order of appearance)

  1. Milkweed growing along fence: Deb Marcinski
  2. Milkweed growing in yard: Karen Oberhauser
  3. Milkweed growing in park: Ilse Gebhard
  4. Milkweed growing along roadside: Gail Gilliland
  5. Senescing milkweed: Carol Pasternak
  6. Measuring milkweed density: Monarch Lab Photo

Glossary Terms (in alphabetical order)


protection and preservation through careful management.


singular, datum: factual information that can be used as a basis for understanding something.


a system of interactions between a community of living organisms and their environment.


the waste product of larvae, called caterpillar poop by most. Monarch larvae produce a lot of this, especially in their later instars.

Oe (Ophryocystis elektroscirrha)

a protozoan that infects monarchs and is known to decrease health, fecundity, and life span. It is passed by infected females to offspring when protozoan spores are rubbed onto milkweed (eaten by developing caterpillars) as they are laying their eggs.


insects that lay their eggs on or inside another insect species (called their host). The eggs hatch and feed on the host from the inside, eventually killing the host.

sample size

the number of replicates in an experiment. Larger sample sizes reduce the effects of random chance.

tachinid flies

(tah-KIN-id): a fly family with about 1300 species in North America. Parasitic tachinids usually attach eggs to the outside of the host’s body. The eggs hatch, then the tachinid larvae burrow into the host and begin feeding inside. The host is almost always killed. The species that live in monarchs are gray and smaller than houseflies.


a sample strip of land used to monitor plant or animal populations and distribution within a given area.

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