Monarch Life Cycle
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Monarch Life Cycle:
Background:
Monarchs have different tasks, depending on what type of the year they are born.
Monarchs that are born in the spring or summer, will become reproductive in a few days.
Monarchs that are born in the fall are in a reproductive diapause that is a suspended form
of development. Even though they may look like adults they won’t mate or lay eggs until
the following Spring.
Monarchs cannot survive a long cold winter. The Monarchs that emerge in the late
summer or fall that fly south to spend their winters in a warmer climate Monarchs that
spend the summer breeding season in the states west of the Rocky Mountains are thought
to migrate to the southern coast of California where they will winter or roost in
eucalyptus trees. The Monarchs East of the Rocky Mountains will migrate to Texas and
Mexico. In Mexico Monarchs roost in Oyamel fir forests, which only occur in a very
small area of mountaintops in Central Mexico. The tall trees of the Oyamel are on a
steep, southwest-facing slope of the mountains at 3000 meters above sea level. Tall trees
for cover, protective shrubs to shield them from snow and rain, cool air and the presence
of water are all important elements that must be present to ensure survival of the
Monarchs in their winter habitat.
Monarchs will cluster together in trees at sites in Mexico and Southern California. Often
they will cover entire tree trunks and branches. As the winter ends and the days grow
longer the Monarchs will become more active and begin an intense period of mating.
This will last 3 to 5 weeks. Around the middle of March the Monarchs will begin to leave
their roosts, flying north and east looking for milkweed plants on which they can lay their
eggs.
All insects change in form as they grow; this process is called metamorphosis.
Butterflies and moths undergo complete metamorphosis, in which there are four distinct
stages: egg, larva (caterpillar), pupa, and adult. Hormones circulating within the body
trigger the changes that occur during metamorphosis. It takes monarchs about a month to
go through the stages from egg to adult. The monarchs that emerge from their pupae in
the fall or late summer are different physically and behaviorally from those Monarchs
that emerge in the spring. A physiological response in the Monarch is signaled through
unfavorable environmental factors. These environmental factors trigger the nervous
system to put the development of their reproductive organs on “hold”(diapause). The
environmental factors involved are the length of daylight, the air temperature and the
quality of the host plant, which is the milkweed.
Students often know more about a topic than they realize. Using the KWL strategy,
students will explore their existing knowledge and then expand it thru the inquiry
process. Along the way teachers can identify and address any student misconceptions. A
central focus of this activity is to encourage students to discuss their current ideas through
the inquiry process. This is an excellent way to fully engage students’ interest in the
activates that follow and build their understanding of scientific concepts.
Engagement:
Give student groups pieces of chart paper that have the words KNOW/ASSUME at the
top. Ask them to list everything that they think they know or assume about the life cycle
of the monarch butterfly. If there is a question about some of the information, have them
indicate that with a star. Have groups post their charts and look at all the information
generated and discuss.
Give groups another piece of paper and have them list questions that they have about the
monarch and it’s life cycle. Ask the groups to post these questions. Allow ample time for
the class to respond to all the groups’ lists.
Ask the students to divide the questions into 2 groups: those that can be answered with
reference materials and those that can’t. For example how many hours during the day
does a monarch travel? Is a question that can be answered with a reference book. Ask the
students to choose at least one question that will need reference materials to be answered.
Help them decide how they will go about answering their question.
A question that cannot be answered simply with reference materials could be termed
open ended. An example of this could be: Why aren’t there laws protecting the
Monarch’s over wintering habitat. Help students design a model for these speculative
questions. Surveys, debates, “ask an expert” and group discussions may be a few ideas to
deal with these difficult questions.
Some of the questions will be able to be answered with direct observation of your
classroom-reared monarchs, students will learn and observe the life cycle of the butterfly
as it moves thru its life stages in the classroom. They facilitate continuation of the
monarch life cycle by optimizing food, light, heat, and space requirement for their own
butterflies. These observations will be journalized. A glossary of butterfly terms has been
included in this lesson plan.
Objective:
1. Students will document in their science journal, the life cycle of the butterfly as it
moves thru its life stages in the classroom.
2.Students will facilitate continuation of the monarch life cycle by optimizing food, light,
heat and space.
3. Keep a journal of observations of monarch (or other butterfly or insect) development,
including descriptions of physical appearance, and a graph of milkweed consumption.
4. Keep a calendar that illustrates size and life cycle stage.
5. Sequence the stages of monarch development and label them.
6. Find and sort pictures or plastic models of the monarch life cycle, based on physical
characteristics.
7. Determine how much milkweed a monarch larve eats by graphing the consumption.
Indiana Standards:
Include standards that are met with this exercise.
Materials:
Milkweed plants (if you can’t find your own you may order them from
www.monarch@ku.edu)
Monarch larvae (if you are lucky enough to find your own, great otherwise a rearing kit
from Monarch watch comes with 14-16, 3 to 5 day old larvae. www.monarch@ku.edu)
Monarch daily observation sheet (1 per student)
Rulers with mm marks clearly visible
Balance accurate to the nearest mg is highly desirable
Monarch class data sheet
Container for the milkweed and larvae
Engagement:
Tell students they will follow the lifecycle of the Monarch Butterfly from egg to
releasing the adult butterfly. Discuss with students how they will keep detailed records of
the growth and development of their larvae. In their science journals. Hand out Monarch
Daily observation charts and milkweed plants, which contain larvae and or eggs. Do the
first observations together. (If you do not have an accurate balance for weighing larvae,
just record the lengths.)
Exploration:
The exploration will give you practical tips for successfully rearing Monarch’s. Please
clean their containers often. It is not good for them to live in their own waste (frass). This
will ensure your Monarchs emerge disease free. If you rise more than one generation,
wash the containers with 10% bleach in between generations.
The Egg:
Monarch butterfly eggs are somewhat difficult to find in the field. It takes 3-5 days for
the eggs to hatch, timing is critical. The best way to do this is watch for Monarch’s
stopping at Milkweed plants. The female will usually lay only 1 egg per milkweed plant
to ensure enough food for the larvae. The egg is usually laid on the underside of the leaf.
Females prefer young plants on which to lay their eggs. If you do find an egg, collect the
whole plant and put it’s stem in water as soon as possible. If you have taken just a leaf,
keep it in a closed environment to control loss of humidity. The top of the egg will look
dark before the larva is ready to emerge. Be sure to have fresh milkweed available, if the
other becomes dry.
1. Observe the monarchs in the classroom habitat. By charting observations daily or
every other day
The Larva (caterpillar):
Once the larvae emerge they will need a continuous supply of fresh milkweed leaves.
They will not eat any other plants. Be sure to replace leaves when they are dry (every 1 to
2 days) Leaves will keep longer if the stem is wrapped in moist paper towel AND then
wrapped in plastic or foil wrap. The containers should be emptied of frass (larva waste)
every one to two days. If milkweed is kept in a closed plastic bag and refrigerated, it will
remain fresh for several days. The larvae can be handled safely at day 3 or 4. But try to
handle them as little as possible until they are at least over 1 inch long. Do not handle the
larvae at any time if they are molting. You can tell they are ready to molt when they
remain very still, often they are on the side or the top of their container. Just after they
have molted, their tentacle will look droopy and you may be able to see the old skin
behind their larva. They usually eat this skin.
As the larva grows so do their appetites. Be sure to check the condition of the leaves
often.
The Pupa:
When larva is ready to pupate, they will crawl to the top of their cage and attach
themselves with a silken thread, called the cremaster. They will form a prepupal “J”
before shedding their skin for the last time. This process is fun to watch but it happens
very quickly. The adult will emerge in 10 to 14 days. When it is ready to emerge the adult
wings will be visible thru the pupa covering.
The Adult:
Adults usually emerge in mid morning. If the pupa is dark and the orange and black
wings are visible, chances are you will see the adult emerge. Some Monarchs die in the
pupa stage. If the pupa has been dark for over 48 hours it is probably dead.
Allow the newly emerged adult plenty of time to inflate its wings and for the wings to dry
before handling. This will take up to 3 to 4 hours. When holding a butterfly, always hold
all 4 wings at once in their vertical position. Despite what you may have heard, it is all
right to hold a Monarch. if you do it carefully. Because they live a long time, and many
of them undergo a rigorous flight they are relatively sturdy.
You may either keep you adult in the classroom for the students to study further or you
may release them. Those emerging in the morning should be ready being the end of the
day and those emerging in the afternoon should be released the following day. If you can
release them on a sunny day (above 60degrees) and near flowers) If it is colder than 60,
often they cannot fly. Adult mass may be measured by placing the butterfly in an
envelope. Be sure to subtract the mass of the envelope from the total.
2. When the butterflies emerge, summarize all data on the Class data sheet.
3. Use the class data to answer questions about monarchs. Students can use
questions that interest them or you can facilitate with some of the following.
-
Do large caterpillars produce large butterflies
Which are larger males or females
Do males or females emerge sooner from the chrysalis
What was the average length of time in the pupa stage
What is the sex ratio of monarchs our class raised
How much growth occurs in a single day at the end of the larval period?
4. Record life cycle data on a class calendar. Make a drawing for each monarch
everyday, so the calendar will show when they formed a J, when they pupate, and
when the butterflies emerge.
Note: To help students with their observations below is a list of guided observations
to use.
• Describe the size of the caterpillar. Compare it to something of similar size or
measure it.
• Describe its color and pattern.
• Describe the body.
• What does the head look like? Can you see eyes? Mouthparts?
• Do you see legs? How many? What do they look like? Where are they?
• What does the caterpillar feel like?
• How can you tell the front of the caterpillar from the back?
• How has the caterpillar changed from the last time you observed it?
Behavior of the Caterpillar
• How does the caterpillar move?
• What happens when you touch it?
• What does the caterpillar do in your hand?
• What do the caterpillars do when they touch each other?
What happens when you touch the black things sticking out of both ends?
• Describe what the caterpillar does when it eats?
6, Students can graph milkweed consumption and record information about the monarch
development.
On the graph record the number of leaves your caterpillar eats every day. When
complete, review the graph and look for patterns. Write a paragraph about your
conclusion, using the glossary of butterfly terms to help with interpretations.
Make several careful observations of your caterpillar. Describe and illustrate its
behavior. Students can use the questions from above to help guide them. Compare and
contrast from your last journal entry.
Overview Task (for Teachers)
Students will keep a daily journal of the growth and behavior of a monarch. In addition to
recording data (length, weight etc.) they will record observations, impressions,
predictions, comparisons, questions and feelings. The journals should include pictures
and words.
Overview Task (for students)
1. Obtain a larva or egg and prepare a proper habitat for it. (This could be set up into
stations)
2. Take care of the larva as best you can. Give it fresh milkweed and clean away
frass daily.
3. Make daily entries in your journal.
a. Record length and weight in millimeter and milligrams
b. Describe changes in your monarch since your last entry
c. Write sentences that describe the behavior of your monarch: movement,
feeding, excretion, molting, silk spinning etc.
d. Write a question of something you would like to know every day
e. At least twice a week include predictions of what you think will happen
next tin your monarch’s lifecycle.
f. Include at least 2 drawings per week
g. You may also include: comparisons, opinions, photographs, reactions
Example of a journal entry:
Entry #1 9/6/05 today was my first day in science. I received a monarch egg. It is creamy
white in color. I measured it with a ruler. It was about 0.5 mm wide and 1 mm tall. It is
shaped like a lemon. I looked at it under the blue scope and it has lines and ridges on its
surface. (Drawing)