Raising Monarchs in captivity: a detailed guide

This blog post is written as an instructional guide for educators raising monarchs in their classrooms. Some information is specific to certain teachers.

Monarch Butterfly Release Party at the Dunbar Memorial Garden

Raising Monarchs

  • INSTARS:
  • Egg hatches at about Day 4
  • 1st instar (1-3 days) caterpillar is very small with pale stripes and no antennae, it will reach ¼” in length
  • 2nd instar (1-3 days) short stubby antennae are present, it will reach 3/8” in length
  • 3rd instar (1-3 days) dark head capsule, longer antennae, it will reach ½” in length
  • 4th instar (1-3 days) no head capsule, thicker black stripes, long front antennae, it will reach 1” in length
  • 5th instar (3 -5 days) white spots on leg triangles, wide black velvety stripes, it will reach 1 ¾” length
  • Chrysalis (8-15 days)
  • Butterfly (2-5 weeks in Summer OR 9 months in Fall if migrating)

The female Monarch lays eggs on the underside of milkweed leaves, usually on the upper leaves (newer leaves) and also on the milkweed flower buds. The eggs are creamy white in color. She usually only lays 1 egg per plant stalk to assure enough food for each egg. Eggs can be “harvested” by removing the leaf or cutting a part of the stem and leaf but because the leaf will dry out even if it is kept wet, it is generally easier to wait until after the caterpillar has hatched and reached 2nd instar. If an egg on a leaf is collected pay close attention to it, as soon as the leaf begins to wilt and dry up there MUST be a new leaf immediately nearby. An egg hatches after 4 to 6 days and if the milkweed is dry/dead/inedible the egg may not hatch and if it does hatch, the cat may die because it cannot consume a dry leaf.

Basically the caterpillar needs only food (milkweed) and a container that is regularly cleaned of “frass” (poop). The container must have a lid or the caterpillar will wonder off. It is amazing how far they can travel.

My favorite containers are clean clear plastic ones with an opening easy enough to fit your hand in. It is MUCH healthier for each caterpillar to be in a separate container – it prevents them from “eating” their housemate(s). Caterpillars cannot see and if there is an egg on a leaf or even a smaller caterpillar they will eat both. Their job is to eat, it is our job to keep them as safe as possible. Additionally, when caterpillars are all kept together in containers there is a higher chance of spreading disease which can result in death which is a lesson to learn but not a pretty one, especially for children.

The most important thing about using plastic containers is that they can be sterilized between uses. Once a butterfly has emerged and been released the container should be cleaned with a 20% bleach solution. Add about ¼ cup of bleach to the container then fill it with warm water. Let it sit for about ½ hour then pour out and add clean water with a bit of dishwasher soap. Rinse several times with water.  Wipe or air dry before reusing.

Inexpensive and disposable containers such as clear 1 gallon bottled water jugs ($1 each at most stores) with the tops cut off are my favorite because they are easy to clean and easy to dispose of as needed. They are also tall enough to keep a small vase or cup of water with milkweed inside, preventing the necessity of daily harvests of milkweed which can be time consuming.

It is important to remember that the caterpillar is “captive” inside that container. Before replacing its food the milkweed should be gently rinsed in cool water to remove any possible predators. Examining the stalk of milkweed before cutting is a great help too, checking not only for bugs but also for eggs!

Basic setup is: a clear clean container, a small vase or small cup with water and a cling wrap top (secure the cling wrap with a rubber band). The cling wrap acts as a barrier and prevents small cats from inadvertently falling into the water and drowning.  Poke a small hole in the middle of the cling wrap and insert the milkweed stalk. The caterpillar will move to the new milkweed on its own. As the cat eats it poops so once a day (or 2 for smaller cats) simply pick up the vase with the cat and set it on a level surface then dump the frass into the trash or outdoors, it is good fertilizer! The container does not need to be rinsed if the same cat is going back into it but try to knock out all of the frass or use a paper towel to wipe it out.

I use a paper towel over the top of the plastic container held in place with a large rubber band. I also poke small holes in the paper towel with a stick pin, just to be sure there is air circulation.

Keep containers out of direct sunlight and away from any air conditioning vents or fans. A sunny window is NOT a good place to keep them as the heat will be intensified in the container and could literally fry them.  Try not to move the cats when they are being very still and not eating – they molt (shed skin) several times which is a labor intensive process and they should not be disturbed at that time.  While there is no harm in the students touching the caterpillars they should never try to lift them off of a leaf as it can damage the “suction cups” on the bottom of their “legs.” When the caterpillar reaches 5th instar it is fun to see how they react to noise – saying BOOP in a high pitched voice will often make them bop their heads up and down.

It is most important during the 5th instar to be observant: if the cat appears to have stopped eating and moving it means they are soon to go into chrysalis and should not be disturbed.  I add a long stick to each jar before this time again making sure it is free of predators (bamboo skewers are great to use for this!).  Often they will use the stick to hang on but they will most often use the top of the jar and make their chrysalis on the paper towel or even use the stalk of the milkweed to hang on. If you are lucky enough to see this happening it is fascinating. They will hang in a “J” form for many hours and eventually molt their final skin to reveal a bright green new skin underneath which is the chrysalis. Try not to move the container for at least 24 hours so the chrysalis can harden. After that time the container should be cleaned of any remaining frass and milkweed. Try not to touch the chrysalis but also try to keep it in a hanging position. If the chrysalis is on the paper towel just hold the towel in one hand and dump the container out with the other. If the chrysalis is on the stalk of milkweed lift the vase out (keep the stalk in water so it won’t dry out). If the chrysalis is on the stick lift it gently with one hand and dump the container with the other. You’ll get the hang of it! It is important to clean out the frass before the butterfly emerges to keep the environment healthy.

The day before the butterfly emerges the chrysalis will appear to have darkened and look black. It is actually a clear chrysalis so what you are seeing is the color of the monarch wings. It is VERY important that the container is not moved or disturbed at this time! Most butterflies emerge fairly early in the morning (7 to 9am) and when they do it is an awesome sight. They split open the bottom of the chrysalis and then grab onto the shell holding tight as they begin to pump fluids from their body to their wings. The butterfly will appear very misshapen with a very swollen abdomen. A small amount of meconium (orangeish fluid) will be noticeable in the bottom of the container. It is not blood and there is no need to be alarmed. As the butterfly holds onto the shell it will swing back and forth – this is how it pumps the fluid to its wings. It happens quickly and soon it will be flapping its wings. It will hold onto the chrysalis for several hours until its wings have dried. (The stick in the container is also a “backup” just in case the butterfly loses its grip on the chrysalis and falls).  Try to wait about 3 hours before moving the container. After that point it can be released into the garden. Do not worry about food or drink. The butterfly does not need either until it is at least 24 hours old.

RELEASING BUTTERFLIES:

Take entire container outside. If it is storming or raining hard try to wait until later or up to 24 hours. Butterflies cannot fly well in rain. Place container on the ground and remove the paper towel lid. Sometimes the butterfly will be so anxious to get out it will fly away as soon as the lid is removed. Most times you can gently insert your hand into the container and it will grab onto your fingers. Very slowly lift your hand out of the container, if done carefully the butterfly will often cling to you for several minutes making for great photo ops! If you don’t want to handle the butterfly at all simply turn the container on its side and it will eventually find its way out.

Let’s Talk about Milkweed:
Monarchs have a reputation among their predators for being “poisonous” and untasty. They ARE poisonous and they get that from the toxins produced in the milkweed that they eat as caterpillars. The milky white sap that is in the stems (and leaves) of the milkweed is also a skin irritant to humans. Proper care should be used when cutting and handling milkweed. ALWAYS wash hands with soap and water after cutting or touching milkweed. Gloves are a good idea as well. Children should never handle cuttings.

Fresh cuttings of milkweed should be given to the cats every couple of days because after a few days the milkweed in the containers will start to wilt and dry up even if it is in water. Failing to give the cats fresh milkweed could result in their death. A cat left in its container in which all the milkweed has been consumed will attempt to go into chrysalis early, at that point the chances for success are slim. It is extremely important for 5th instar cats to have a ready supply of milkweed – their container should be checked several times a day to make certain of that.

Best success without waste of milkweed is to take cuttings that are approximately 3 to 4” tall (4 to 6 leaves per stem). Any larger and the milkweed will dry out or start to yellow before it is consumed. Again, be sure to inspect and remove any bugs and rinse well or wipe each leaf off with a damp paper towel. Get the cuttings into water as quickly as possible and always try to harvest milkweed early in the morning or late in the evening. Cuttings taken during midday or when the plants are in full sun will often result in wilted cuttings that dry up and die before they can be consumed. Even with the best of handling some stalks of milkweed will simply dry up and be inedible very quickly.

As the season progresses more and more predators find the milkweed. Even beneficial insects such as lady bugs will consume monarch eggs while feasting on aphids. Spiders also eat young cats and unfortunately a young cat may inadvertently consume an egg or even a smaller cat while it eats. Ants that are on the plants to harvest honeydew from aphids will kill small cats and eggs. While a female monarch can lay hundreds of eggs, in the wild the chances of her offspring’s survival is rather slim: about 90% of her eggs will not make it to chrysalis. It is particularly important in August and September to be very diligent when harvesting milkweed to remove all insects before using it for food for captive cats.

A note about Tropical Milkweed (this is planted in the barrels)

Tropical Milkweed is a non-native annual that will not reseed (the seed cannot survive our winter temps). While it is shunned by native plant purists, there are many reasons why we continue to grow it as a food source: it is easy to start from seed each year, it handles being cut for food since it resprouts quickly, it harbors fewer predators and it stays fresher in vases longer than other milkweeds. Seed pods from each year’s plants can be saved and stored for the following spring. Pods are “ready” when they turn brown and begin to split open. Seed inside should be brown. Undeveloped and unusable seed will be white or light tan, it should be discarded. Remove seed from “fluff” and store in an envelope in a cool dark place (inside a desk drawer is fine). We’ll get you started with seeds and instructions for next year’s plants.

One final note: sometimes no matter what we do or the precautions we take a cat or butterfly just won’t make it. While my failure rate over the past 10 years has been minimal, I expect much of that has to do with not only being overly-cautious and careful but also because I raise them in a quiet home environment with minimal handling and disturbance which I expect is not so easily done in a busy, active classroom full of enthusiastic young children. The risk is worth it: the long-term impact of observing butterflies in the classroom could help spawn a new generation of butterfly enthusiasts, conservationists and hopefully a future lepidopterist or two!

After watching a Monarch emerge from its chrysalis, this young enthusiast was able to release it at the Dunbar Memorial Garden
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