Key Points: Monarch Larva Monitoring Project Online Training
To help you follow along with the training videos, we’ve highlighted the main
topics of each section. Please feel free to use this guide during the training and
afterward for review. Thanks for participating in the MLMP!
Section 1A: Identification Skills – Monarch Eggs and Caterpillars
- Like all other Lepidoptera (butterflies and moths), monarchs undergo complete
metamorphosis (egg, larva, pupa, adult).
- Monarch eggs are about the size of a pinhead, have longitudinal ridges, and hatch after 3-8
days, depending on temperature.
- Monarchs have 5 larval instars, and they molt, or shed their skin, between each instar. The
caterpillar stage lasts about 9-16 days.
- It is fine to call butterfly and moth larvae caterpillars.
- Look for characteristic chew marks or frass when trying to find caterpillars.
- Tricks for distinguishing monarch instars (size is not always a reliable identification tool):
- 1st instar – tentacles not visible
- 2nd instar – tentacles barely visible on front and back
- 3rd instar – front tentacles reach the tip of the head if extended forward
- 4th instar – tentacles reach beyond the front of the head
- 5th instar – tentacles even longer and droop towards the ground
Section 1B: Identifying Monarch Pupae and Adults, Milkweed, and Nectar Plants
- Chrysalis is the term for a butterfly pupa; cocoon is a term for the silk (or other) covering around
many moth pupae. A monarch pupa is called a chrysalis, not a cocoon.
- The pupa stage lasts 8-15 days in monarchs.
- Monarchs rarely pupate on milkweed (but sometimes they do!).
- Female monarch wing veins are generally wider than males.
- Male monarchs have a dark spot on each of their hind wings.
- Adults in breeding generations live 2-6 weeks; adults in the migratory generation can live
7-9 months.
- Larvae only eat milkweed; adults feed on a variety of nectar plants. There are over 100
milkweed species in North America.
Section 2: Migration and Overwintering
- No life stage of monarchs can survive long periods of freezing temperatures.
- Shorter days, cooler nights, and aging milkweed trigger reproductive diapause in migratory
monarchs. Monarchs in diapause put off reproduction until conditions are favorable, usually in the
following spring.
- Fall migration to Mexico begins in about mid-August, whereas western migration to California
generally begins in October.
- Monarchs east of the Rocky Mountains migrate to central Mexico, and monarchs west of the
Rocky Mountains generally migrate to the coast of California. However, some monarchs
from the west migrate to Mexico, passing through southwestern US states.
- Oyamel fir forests serve as a blanket and umbrella for monarch overwintering colonies.
-
Black-headed grosbeaks and black-backed orioles eat adult monarchs in overwintering clusters.
Monarchs eat very little during the winter, although they need access to water to prevent
dessication.
In March-April, butterflies from Mexico disburse from the colonies and reach the southern U.S.,
where they produce offspring that will continue the journey to the northern breeding grounds.
In February, butterflies from California overwintering sites disburse east and north to breeding
grounds.
Section 3A: Monarch Larva Monitoring Project
- MLMP began at the University of Minnesota in 1994, and citizen scientists began
contributing data in 1997.
- MLMP data help us understand monarchs and their biological needs, survival patterns,
population trends, and the impacts of many kinds of environmental changes on monarchs.
Plus, participating in the project is fun and educational.
- MLMP data can inform conservation efforts and have been used in many scientific
publications.
- All MLMP datasheets have detailed instructions.
- Don’t forget to enter the data that you collect online at our website (www.mlmp.org).
- You can order a monitoring kit for supplies to help you while monitoring.
- There are many different MLMP activities, but you can pick and choose the ones that are
most interesting to you.
Section 3B: MLMP Activities – Site Description and Measuring Milkweed Density
- Any site that contains milkweed can be a monitoring site, but it is important that it is not
treated with pesticides.
- Fill out the site description form and enter this online, being sure to update site
information every year.
- Measure milkweed density once a summer, during the middle of the growing season.
- Count all milkweed if possible, otherwise do a random sample to estimate milkweed
density.
- Accurate milkweed density is important in determining monarch larval density.
Section 3C: MLMP Activities – Measuring Monarch Density
- Monitor milkweed in your site to get a per plant density of monarchs.
- Examine as many plants as possible; do this once per week at about the same time
(although it’s fine if you need to miss a week or two during the summer).
- If there are too many milkweed plants to observe them all, monitor a random sample.
- Datasheets 1A, 1B, and 1C are similar; you only need to use one of them. 1B works well for
young children, and 1C collects additional data on the number of monarchs on each plant
that you observe.
- Look closely at plants, but be careful when handling them so that you don’t knock
monarchs or other insects off of them.
- Keep track of monarchs that you find on the datasheet.
- Keep track of disturbances (like mowing or burns), plants in bloom, and presence of bright
yellow aphids on milkweed plants.
Section 3D: MLMP Activities – Milkweed Characteristics
- Data on milkweed characteristics can help to determine how female monarchs choose
milkweed for egg laying.
- Observe both plants with monarchs (Datasheet 4A), and random plants (Datasheet 4B).
- Record plant species, height, presence of other invertebrates, buds, flowers, seed pods,
overall condition, and herbivory or disease. You will also need to count all other milkweed
growing within 1 square meter of each plant observed.
- Only record the first 30 plants with monarchs on them for this activity on Datasheet 4A,
then observe the random plants and record the information on Datasheet 4B.
Section 3E: MLMP Activities – Monarch Rearing, Survival, and Parasitism
- Data collected for this activity will help determine monarch survival in the wild.
- Collect monarchs (larvae or pupae) from the wild, rear them inside, and record the fate of
the monarch on Datasheet 3.
- If you’d like to study OE, a protozoan parasite, visit www.monarchparasites.org for more
information.
- Record the date, location of collection, and stage of monarch when collecting monarch eggs
and larvae.
- Record if a monarch ecloses as an adult, dies from parasitoids, or dies from another cause.
- Send adult parasitoids to us, using the address on the datasheet.
- Keep larvae in an easy-to-open container with holes for air exchange.
- 3 keys to successful rearing: Keep the cage clean, keep milkweed fresh, avoid extreme
temperature and moisture conditions.
- Clean cages daily, and bleach containers and surfaces often.
- You can collect, wash, and store milkweed in the refrigerator.
- Tachinid fly larvae may emerge from monarchs in the pre-pupa or pupa stage.
- Adult wasps may emerge from a monarch pupa.
Summary: A Day in Your MLMP Monitoring Site
- First fill in date, observers, site name and location, time, and the temperature in the shade.
- Start observing plants and recording data.
- Monitor all plants, or randomly choose plants to monitor.
- If you participate in the Milkweed Characteristics activity (activity 4), fill in datasheet 4A as
you find monarchs on the plants, and do the random sample when you have finished
monitoring.
- If you participate in the parasitism study (activity 3), collect 4th and 5th instars and record
on Datasheet 3.
- If you want, keep a record of rainfall at your site (Activity 2).
- Enter your data online at www.mlmp.org.
Final Reminders and Thanks
- All activities for MLMP have datasheets with detailed instructions.
- Data accuracy is important! Don’t hesitate to ask us questions (info@mlmp.org).
- Choose to do whichever activities you want to, nothing is required, and you are free to take
vacations.
- Your feedback will help us improve this resource.