Complete guide: How to raise Monarch butterfly caterpillars at home

If you’re trying to figure out how to raise Monarch butterfly caterpillars at home, you’re in the right place! Our family has many years of experience successfully raising Monarch butterflies and this guide will help you do the same!

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This is a very detailed guide intended to help you successfully raise Monarch butterflies at home while answering every relevant question you might have about the process. Hopefully, we answer any general questions you might have about the majestic Monarch butterfly as well.

The guide is broken into four sections: 

• Part I. Context: the charismatic Monarch butterfly & why they matter 
• Part II. Why raise Monarch butterflies?
• Part III. How to raise Monarch butterflies in your home: a step-by-step guide
• Part IV. Monarch butterfly FAQs

We highly recommend you read this article in its entirety before attempting to raise Monarch butterflies in your home. 

Part I. Context: the charismatic Monarch butterfly & why they matter

Ecologists express mixed feelings about charismatic species. If you’ve never heard the term before, “charismatic species” are the ones that human beings tend to care the most about due to some combination of their beauty, impressive physical traits/athleticism, or endangered status. 

While it’s great for people to care about a beautiful or fast-running species, why not care about the little “ugly” ones too? After all, in the interconnected web of life, doesn’t an endangered American Burying Beetle have as much import as a Monarch Butterfly? 

In our minds, the answer is yes. However, charismatic species can serve a critical role: they help draw us humans into a state of greater empathy, connection, and concern about the natural world. And that’s a good thing. 

Monarch butterflies: the attractive and threatened spokesmodel for butterflies and insects 

Likewise, Monarch butterflies (Danaus Plexippus) — a charismatic butterfly species — are beloved because of their exceptional beauty and their extraordinary long-distance migration pattern. In fact, Monarch butterflies undergo the longest two-way migration of any insect on earth, which is also the reason they have such huge wings.   

These attributes have earned them their name: “Monarch,” the king of butterflies. There are also similarly colored Viceroy, Queen, and Soldier butterflies that don’t get as much popular attention as Monarchs do.

Monarch butterflies’ populations have declined by 80% in North America in the past 20 years, and they may soon be considered an endangered species in the US (despite a recent small uptick in their population numbers). This population decline has further boosted public awareness, concern, and love of Monarch butterflies.   

No insects, no people. 

Perhaps you’ve heard headlines from around the world about the insect apocalypse, massive population declines across virtually every species of insect. What’s causing this terrifying trend?    

According to recent research, insect population declines in the US are largely being driven by the fact that today’s agricultural landscape is nearly 50 times more toxic to insects than it was 25 years ago. New classes of synthetic pesticides in use today — namely neonicotinoids and pyrethroids — are the primary culprits behind this heightened acute insecticide toxicity loading (AITL). 

Coincidentally, the typical American lawn is actually just as bad or worse than our agricultural landscapes – all to grow a monoculture of grass. Shrinking habitat + more extreme weather + higher toxicity loads is creating the perfect deadly storm for all insects, including Monarch butterflies.  

Why should you care whether insects live or die? Because you care about whether you live or die.

As Harvard entomologist E.O. Wilson and others have pointed out, if insects disappear, so too will most terrestrial life — including humans (due largely to food shortages). Whether we like it or not, our fates are intertwined with insects.  

Part II. Why raise Monarch butterflies? 

Successfully raising Monarch butterflies requires considerable knowledge, work, and time. However, there’s an indescribable joy you experience when you release an adult Monarch butterfly into the wind and watch it joyfully use its new wings for the first time. 

You can raise Monarch butterflies for any number of reasons:

• school project/children’s hands-on educational project; 
• to help fully grown adult humans gain more of a connection to the natural world;
• because it’s fun, interesting, and rewarding;
• to help boost Monarchs’ population numbers.

Please note that we are NOT recommending that you raise thousands of Monarchs, have over-crowded conditions which foster disease, or buy Monarch chrysalises from commercial vendors. Doing so can actually hurt the species as well as hindering public efforts to monitor their population numbers and health. Read more about this from Xerces Society. 

If you’re interested, what we are recommending is a small-scale, thoughtful, and careful approach to raising Monarch butterflies in your home. 

What is the success rate of raising Monarch butterflies indoors vs outdoors? 

Over multiple years and between three different households in our family raising Monarch butterflies, our overall success rate raising Monarch caterpillars indoors is well over 90%. Each year, we’ll have a few that will die as caterpillars (often due to our accidents).

In the wild, Monarch butterfly eggs and caterpillars aren’t nearly so lucky. A female Monarch butterfly will lay 300-400 eggs. Of those, it’s estimated that at least 90% will not make it to become an adult butterfly. (Yes, Monarch eggs and caterpillars are a food source for other predatory species.)

Thus, by raising Monarch butterflies indoors, you can create a 90%+ survival rate vs a 90%+ death rate outdoors. So, your small yard or garden could ultimately produce as many Monarch butterflies as an ideal feeding ground 10x larger! That’s quite a magnifying effect.    

To achieve this high success rate, you’ll need to do some learning, get the necessary material/equipment, and dedicate yourself to properly feeding and cleaning up your indoor Monarch enclosure on a daily basis.

We’ll show you exactly how to accomplish all of that to successfully raise your own Monarch butterflies. 

Part III. How to raise Monarch butterflies in your home: a step-by-step guide 

1. Preparing for Monarch butterflies

Proper preparation is critically important for successfully raising Monarch butterflies.

A. OUTDOOR preparation for Monarch butterflies and caterpillars 

Monarch caterpillars feed exclusively on various species of milkweed (Asclepias). That means you’ll need to either:

• grow LOTS of milkweed in containers and/or in your yard or garden (without using any pesticides);
• have access to LOTS of nearby wild milkweed that is NOT sprayed with pesticides;
• or both.

We recommend both (growing and foraging milkweed) because it’s always nice to have backup. Monarchs caterpillars are voracious eaters, and if they run out of food, they will die. You can’t have too much milkweed around when you’re raising Monarchs. 

Warning: Milkweed plants you find at a local nursery may be sprayed/treated with pesticides. If you buy milkweed plants for your Monarchs, make absolutely certain that no pesticides have been used or you’re likely to kill your caterpillars. 

How much milkweed do you need to raise Monarch butterflies? 

For each Monarch caterpillar you raise, you’ll need to plan to have about 1′ of mature healthy milkweed plant, which equates to about 20 mature average-sized milkweed leaves. 

Leaf size varies by milkweed variety/subspecies, so it may take more than 20 leaves for small-leafed varieties and less for large-leafed varieties. Common milkweed (Asclepias syriaca) is the subspecies that produces the largest leaves that we know of.

We grow a wide variety of milkweed in small pots that we can bring indoors for our hand-raised Monarch caterpillars. Once they’ve chowed the plant down to the stems, we put it back outside to recover, replacing it with another plant or fresh-clipped milkweed stems/leaves. 

We also grow a wide variety of milkweed in-ground throughout our yard from which we gather leaves AND collect Monarch eggs and caterpillars to bring indoors. In short: if you plan to raise Monarch caterpillars, you can not have too much milkweed!

REPEAT: You can NOT have too much milkweed! 

There are a number of online resources from which you can get free milkweed seeds. Do a bit of research to determine the specific subspecies of native milkweed that grows in your area. You can also use non-native milkweed, but we recommend using as much native milkweed as possible. 

Monarch butterflies’ favorite flowers: attracting Monarchs to your yard  

Female adult Monarch butterflies can smell milkweed from great distances away. If you only have a little room in your butterfly garden, just plant milkweed. Chances are, a female Monarch will pass close enough by to smell it, visit, and lay eggs. Monarchs have wide foraging ranges and can travel up to 25 mph per day in favorable wind conditions. 

Ideally, you have enough room in your garden/yard that you can also grow other flowering plants so your visiting Monarchs can forage pollen and nectar in your yard in addition to laying eggs on your milkweed. Yes, milkweed also produces flowers that provide a good food source for pollinators as well. However, the following flowers seem to be particular favorites for Monarchs in our yard:

• zinnias,
• Mexican sunflowers,
• cosmos, and
• achillea.   

If you need more help with flower selection, Xerces Society has an excellent Monarch Nectar Plant List broken down by region.   

No pesticides – including herbicides

As mentioned earlier, pesticides are not good for insects. This means you should stop using insecticides as a starting point, but also stop using herbicides like RoundUp as well. Yes, poisons designed to kill plants are also harmful to insects (and humans too for that matter).   

If you collect milkweed from the wild for your Monarch caterpillars, you’ll need to be careful to gather it from a spot where pesticides have not been used. 

B. INDOOR preparation for Monarch butterflies and caterpillars 

To raise Monarch caterpillars indoors, you’ll need to have:

• a designated spot to raise your caterpillars in a room that gets a lot of natural light (ideally 6+ hours daily);
• a protected, easy-to-clean enclosure/cage where the caterpillars can eat before crawling to the top to form chrysalises (this enclosure needs to be thoroughly sanitized before and after each use to prevent disease buildup);
• a smaller container to house any leaves with eggs and first and second instar caterpillars until they grow large enough for your primary enclosure (more on this below); 
• access to a constant supply of milkweed (see above for quantity of milkweed you’ll need per caterpillar); 
• containers to hold any cut milkweed stalks upright without drowning your caterpillars.  

Your indoor Monarch enclosure can be as simple as a lightweight mesh polyester laundry hamper. A few problems we’ve experienced using a mesh laundry hamper to raise Monarchs: 

1. you can’t easily see in to enjoy caterpillar gazing;
2. you can’t easily reach in and out to clean, change out milkweed, etc. 
3. since there’s no way to completely secure the opening, when your Monarch caterpillars are ready to form a chrysalis, some of them will likely get out of their enclosure and form chrysalises in undesirable spots in your house. 

If you get a bit more serious about raising Monarchs, we’d recommend you purchase the following supplies: 

• RESTCLOUD Butterfly Habitat Cage – lightweight mesh cage that collapses flat for easy storage | smaller sized cage 15.7 x 15.7 x 23.6 inches (this is the one we use) or larger sized cage 24 x 24 x 36 inches. 
• floral tubes – these help hold up, water, and preserve any milkweed leaves/branches you trim off to feed to your Monarch caterpillars 

Now that you have all your outdoor and indoor preparations in order, let’s go through what you’ll need to KNOW and DO to raise Monarch butterflies at home!

2. Understanding Monarch butterfly generations and life cycles

Two important things you need to know about Monarch butterflies before raising them, are: a) the different generations of Monarchs, and b) their life cycle. 

A. Monarch butterflies typically have four generations per year.  

Unlike many other insects, Monarch butterflies do not overwinter or lay eggs to overwinter. The Monarch butterflies you see in spring are NOT the same butterflies you see in late summer.

Instead, every year usually equates to four distinct generations of Monarch butterflies, and the cycle repeats: 

• Final generation/super generation – Warming weather in February and March triggers overwintering Monarchs in Mexico to mate and begin their migration north and east. This generation dies soon after laying eggs on milkweed in their early migration ranges.  
• Second generation – In May and June, the second generation of Monarchs emerges. They live for about four weeks and continue traveling to new migratory areas, laying eggs on milkweed as they go. 
• Third generation – The third generation (born in July and August) also lives for about four weeks before reproducing and dying. 
• The fourth “super generation” – This generation is usually born between late August through mid-September, with some variability by climate region. This fourth generation of Monarchs is typically the “super generation,” due to some rather extraordinary differences. Rather than only living for four weeks and having a limited flying range, the super generation travels thousands of miles to its southern overwintering ranges in the mountains of Mexico and live until the following spring (about eight months) when they restart the migration back north/east. 
• Exceptions – The number of generations of Monarchs may vary by location and whether it’s an unusually hot or cold year. In cold summers in northern climate regions, the third generation may become the migratory super generation. On the other extreme, there may even be a fifth generation of Monarchs in very warm years, which become the migratory super generation. Also, there are areas of the world where Monarchs don’t migrate at all, and breed year round.   

Which generation of Monarch butterflies should you raise? 

There’s no right or wrong answer here, and it may depend on your goals. If you’re just raising a couple of Monarchs for fun or as a project with your child, it doesn’t really matter what generation you raise. 

However, we place the bulk of our Monarch butterfly-breeding efforts on the fourth super generation. This is due to the fact that:

1. We have a relatively limited supply of milkweed (and time);
2. Monarchs in our area seem to lay by far the most eggs in September; and
3. Generational considerations (see below).

Sometimes, especially in years with extreme weather events such as late heat waves, early freeze events, bad storms, etc), there are large die-offs of migratory Monarchs on route to their wintering spots in Mexico. 

While the success of all generations of Monarchs is essential to the species’ survival, our hope is that the more Monarchs start the fall migration, the more are able to successfully survive the winter and restart the next generations the following spring. This doesn’t have to be your Monarch-raising strategy; we’re simply sharing what we do and why we do it.        

If you raise back-to-back generations, be sure that you’ve thoroughly sanitized the cage and all materials used before starting anew. 

B. Monarch butterfly lifecycle: egg > larva > pupa/chrysalis > adult

Monarch butterflies lifecycle is as follows:

1. Eggs 

Small white Monarch butterfly eggs are laid on the underside of milkweed leaves by adult females. A single female Monarch butterfly can lay between 300-500 eggs over her lifespan. 

Duration: It takes about 3-5 days for the tiny Monarch larva to form inside the egg, eat the egg, then emerge as a first instar larva/caterpillar.  

2. Larvae

There are five “instars,” which are the growth stages of Monarch caterpillars/larvae. Each instar represents a larger-sized caterpillar, and a shedding of the previous instar’s skin. Monarch caterpillars typically eat the shed skin when transitioning to the next instar.   

Duration: The larval stage of a Monarch lasts 9-14 days.  

3. Pupae/Chrysalis 

At the end of the fifth instar larval stage, Monarch caterpillars will stop feeding and go off in search of a spot to form their chrysalis. In the wild, this might be the underside of a leaf or branch.

In a home enclosure, this means they’ll typically crawl to the top of the enclosure. Then, they’ll excrete a silken cremaster, attaching their backend to the ceiling before going into “J”. This simply refers to their J-shape as they hang down in preparation to form a chrysalis.

Monarch chrysalises look like a beautiful piece of jade jewelry with gold dots. 

Duration: Monarchs will remain in their chrysalises for about 8-13 days.  

4. Adults 

At the end of the pupal stage, the chrysalis will turn black in color. However, it’s still translucent enough to see the dark wing veins and colorations inside. 

Your first time watching an adult Monarch emerge from its chrysalis (eclose) is a magical experience for children and adults alike! After emergence, it will take 3-4 hours for its wings to properly dry.

They’ll do quite a bit of flapping and walking around during the drying process to help dry and get proper blood flow to their wings. Other than possibly (very carefully) transporting them to another less crowded enclosure, you do not want to touch them as they’re readying their wings for flight. 

After first flight, an adult Monarch will spend its days flying, pollinating flowers, and mating, similar to a human airline pilot. (Gotta throw in a joke to make sure you’re paying attention.) 

Duration: An adult Monarch butterfly will live anywhere between 4 weeks and 8 months, depending on what generation it falls in. (Remember the “super generation” lives much longer than earlier generations.)   

3. Raising Monarch butterfly caterpillars at home: a step-by-step guide

Step 1: Gather Monarch butterfly eggs, caterpillars, and milkweed.  

A. Gathering eggs and young “cats”

Set up your indoor butterfly cage/habitat (see Part 3 > Indoor preparation for recommended materials).

On the bottom of the enclosure, we place:

• a layer of aluminum foil (which will stay there throughout the entire process), and
• a layer of paper towels on top of the foil (which we change out at least daily or more if needed).      

Now, it’s time to go get Monarch butterfly eggs and/or caterpillars! Go to the milkweed patches in your garden or the wild milkweed patches you’ve identified near your home.

Carefully inspect the underside of the milkweed leaves for small white Monarch butterfly eggs. Early instar Monarch caterpillars are often on the undersides of the leaves as well, but larger late-stage instar caterpillars will often be on the top side of the leaves, stems, and milkweed flowers as well.  

Very carefully gather the eggs and YOUNG caterpillars – the smaller, the more delicate. This often means cutting/pinching off entire leaves so as not to crush the eggs or small caterpillars. Larger caterpillars can be carefully removed from the plant by hand without injuring them.

Place the eggs and caterpillars into a breathable container.

Why only collect young caterpillars and not larger, late stage ones? A common predator that parasitizes Monarch caterpillars is tachinid flies, whose larvae live inside the caterpillar before emerging and finding a new host. The older the caterpillar, the higher the likelihood they’re a host for tachinid flies, which could then attack other caterpillars in your indoor enclosure.  

If you want to eliminate the possibility of having any tachinid flies, only gather eggs, not caterpillars. 

How many Monarch caterpillars should you raise? 

We recommend starting small, with no more than 5-10 caterpillars your first time. You don’t want to be overwhelmed or have your caterpillars run out of milkweed and die. A smaller number also minimizes the likelihood of disease.    

B. Gathering milkweed 

When gathering milkweed as food for your indoor caterpillars, it’s critically important to make sure you’re not bringing predators or diseases into your indoor cage/habitat. 

Remove all other insects such as: 

• Aphids – We’re very comfortable with insects, so we simply smush and/or hose spray off any aphids on the plants by hand. Aphids aren’t predators but they also eat the milkweed and may have parasitoid wasps inside them that can hatch and parasitize your indoor Monarch caterpillars.        
• Spiders – Simply shoo spiders off the leaves while you’re outside. 
• Other predators and predator larvae – The most common predators we see on our milkweed are adult and larval ladybugs (larvae look like red and black alligators), syrphid fly larvae (look like brown or green worm slinkies), and lacewing larvae (look like little crocodiles). Don’t kill them! Simply blow them off onto an outdoor plant and let them continue hunting.   

Once all predators have been removed and you’ve inspected the milkweed plants/leaves to make sure there are no remaining Monarch caterpillars and eggs, give the plant material a good rinse in tap water to reduce pathogen loads. 

We then place stems of milkweed that we plan to immediately use into floral tubes that are placed into empty glasses/jars for support. Those are then put in the Monarch cage.

For milkweed we’re not going to use immediately: we wrap the cut stems in damp paper towels, then place it all into plastic bags that we store in our fridge. (Milkweed lasts for many days properly stored in the fridge.) 

Step 2: Raise Monarch butterflies in your indoor enclosure. 

Large Monarch caterpillars can and will eat Monarch eggs while eating milkweed leaves! That’s why we keep the leaves with eggs on them in a small separate container until they’re in the second instar stage. Then we put them into the main cage with the larger caterpillars. 

Now the Monarch caterpillars do a lot of the work for you: eating and growing. Take time to observe them and enjoy the view. They’re fascinating little critters and their antennae are adorable! 

 

 

 

 

 

 

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Y’all! Monarch butterfly caterpillar enjoying a milkweed leaf buffet. Aren’t these critters adorable? #monarchbutterfly #monarch #monarchcaterpillar #savethemonarchs

A post shared by Tyrant Farms (@tyrantfarms) on Sep 4, 2018 at 3:15pm PDT

Don’t get lazy! Daily maintenance of your growing Monarchs is required: 

• Daily cleaning – You’ll need to clean the frass (aka poop) out of the bottom of the cage on a daily basis to reduce the potential for disease. This means changing out the paper towels on the bottom of the cage, carefully making sure you’re not also getting rid of any caterpillars who might be hanging out on the bottom. (Frass makes great plant fertilizer!) 

• Milkweed changes – Monarch caterpillars can starve to death, and often do in the wild when they run out of milkweed leaves. We typically change our milkweed leaves/stems/plants out every 24-36 hours. If your leaves have been eaten and/or the caterpillars appear irritated and exploring around the cage, you may need to change your milkweed sooner immediately, regardless of how long it’s been.    

Do Monarch caterpillars need supplemental water in addition to what they consume through milkweed leaves? Generally no, but it depends:

• If your milkweed leaves are relatively dried out and limp and you are unable to immediately change them out for fresh leaves, you’ll want to spritz the plants with water in the morning so your caterpillars get the hydration they need. If your milkweed leaves are normal and perky, there’s no need to spray your plants with water. Keep in mind that wet conditions and damp paper towels in the bottom of your cage can encourage diseases.  
• Eggs and first instar caterpillars will benefit from a supplemental early morning water spritz on the leaves they’re consuming.

However, as long as your milkweed is in good condition, your Monarch caterpillars should be fine without supplemental water spray.  

WARNING: One thing you do NOT want to do is place bowls of water in your cage. This can lead to drowned caterpillars.    

Step 3: Monitor the pupae/chrysalises.   

After 9-14 days as a caterpillar, your Monarchs will spend another 8-13 days in the pupal stage inside of their chrysalis, wherein they’ll metamorphose into adult butterflies. 

At some point, you’ll notice your large fifth instar caterpillars stop eating and begin wondering around the walls and top of your enclosure. (The smaller caterpillars do this as well when they’re shedding skin between instars.)

Soon, they’ll excrete silk from their tail ends to form a cremaster, and hang the front of their bodies down into a J-shape (aka “going to J”). After 6-12 hours or so, they’ll then rapidly form a green chrysalis in a matter of a couple minutes, which is an amazing process to watch! 

Over the next 1-2 weeks, they remain inside their green chrysalises, forming full wings and adult body parts. You can see these changes taking place through the semi-translucent chrysalis walls.

What should you do if a Monarch forms a chrysalis in a spot you don’t want it? Or you want to move a chrysalis? 

Using scissors, cut the top of the silken stem where it attaches to whatever object it’s hanging on. Then attach a clip to the top of the stem – tie the clip to the top of your cage and you’re all set! Obviously, be careful throughout this process to put as little pressure as possible on the chrysalis. 

Finally, your chrysalises will turn black, signaling that adult butterflies will be emerging within ~24 hours!   

Step 4: Release your adult Monarch butterflies into the wild.  

Out pops a beautiful adult Monarch butterfly from a tiny chrysalis! Another exciting moment for their human caregivers. 

Now, your Monarchs will need to dry and stretch their wings, while getting their wings’ circulatory system up to speed. This will take a few hours. 

If you want to transport your newly emerged adult Monarch butterflies to another less crowded “holding pen” (which we recommend), do so very carefully. A sanitized mesh laundry hamper or a second RESTCLOUD Butterfly Habitat Cage (small or large) works great as a holding pen. 

The way we transport our Monarchs over short distances between cages: extend your index finger immediately in front of the Monarch’s legs, and get them to walk on to your finger. Then (without touching or pressing on the wings) slowly and calmly bring the Monarch into the holding pen and let it grab hold of the top or sides of the new enclosure.   

How do you know when it’s time to release your Monarch butterflies into the wild?

Temperature – First, keep in mind that Monarch butterflies are cold blooded, so warm external temperatures are essential to them being able to fly. If it’s below 55°F (13°C), Monarch butterflies can’t fly. So don’t take them outside on a cool morning when temps are below 55°F and expect them to fly!

Weather – A warm, sunny day is ideal for your Monarch release. Do not put your adult Monarchs out for their first flight on a rainy or windy day. Doing so could injure or cripple them. Instead, hold them indoors until storms have passed.

If you need to feed them in the interim, use a honey water mix (1 part honey to 9 parts water). Soak a cotton swab in this mixture so it’s damp but not soaking wet. Then tie it to the inside roof of your cage/enclosure so the Monarchs can hang on it while drinking. 

Signs they’re ready for first flight…

A few hours after “eclosing” (emerging from the chrysalis), a ready-to-release Monarch will start taking short flights around its enclosure. At this point, you can transport your Monarchs outside! Ideally, you can take your whole cage outside, open it, and let them find their way out.

Monitor to make sure they all fly away. Watch any stragglers and bring them back inside for a longer waiting period rather than leaving them outside if they’re unable to fly, as they could then be eaten by a predator. Or stay with them while leaving them in their cage outside as they get charged up by the warm sun before flying off.    

We’ve had some make a short flight to a nearby bush before eventually flying off minutes later. Others seem to immediately launch high into the sky, seemingly taking extreme joy in bouncing about on their new wings.  

Wish your babies a good life and safe travels! It’s thrilling to be an intimate part of a Monarch butterfly’s life — from egg to adult — and to cultivate a regenerative relationship with another of earth’s extraordinary species.  

From our family to yours, thank you for your efforts! 

Part IV. Monarch Butterfly FAQs

1. Do Monarch caterpillars eat their skin? 

Yes – at least usually. Monarch caterpillars go through five instar stages before forming a chrysalis. Between stages 1-4, they typically consume their old skin while transitioning. 

2. I think one of my Monarch caterpillars died. What should I do? 

First, note that when transitioning between instar stages, your Monarch caterpillars will crawl off to shed their skin. During part of that time, they may appear to be dead since they’re not moving. 

However, if you definitely have a caterpillar that has died, you’ll want to remove it from the cage asap in case it has parasites or a disease that could spread to other caterpillars. 

How much milkweed does a Monarch caterpillar eat? 

We answer this question above, but it bears repeating since it’s critical that a Monarch caterpillar have adequate food to survive. For each Monarch caterpillar you raise, you’ll need to plan to have about 1′ of mature healthy milkweed plant, which equates to about 20 mature milkweed leaves. 

There is variability in leaf size by milkweed variety/subspecies, so it may take more than 20 leaves for small-leafed varieties and less for large-leafed varieties. Common milkweed (Asclepias syriaca) is the subspecies that produces the largest leaves that we know of.

Want to know how to eat Common milkweed? Read our article Common milkweed: How to eat your Monarch butterfly garden.

Do Monarch caterpillars eat each other? 

Typically no, but this can sometimes happen. For instance, large Monarch caterpillars may inadvertently eat Monarch eggs or first and second instar caterpillars when eating milkweed leaves.

Also, when food supplies are exhausted, the caterpillars can sometimes eat each other or even nibble on other Monarch chrysalises. 

To reduce the likelihood of this happening:

• make sure you provide a steady supply of quality milkweed;
• don’t place milkweed leaves with eggs or first stage instar caterpillars in your main Monarch caterpillar cage where your larger caterpillars are located;
• don’t overcrowd your enclosure (we’re pushing the safety limits in the image above).  

Can you touch Monarch caterpillars?

Yes, with some restrictions! The smaller the caterpillar, the more likely you are to damage it. We recommend NOT handling first or second instars unless absolutely necessary. The larger fourth and fifth instar caterpillars are able to be handled and will be happy to crawl around on your hands. 

Just be sure your hands are clean before handling them to reduce the likelihood of giving them a disease you carried in from outdoors, and return them to their milkweed plant after a few minutes so they can continue eating.  

Can Monarch caterpillars eat anything other than milkweed? 

Monarch caterpillars should be raised on a diet of 100% milkweed. However, if you’re desperate and trying to bridge a gap between replacing your old milkweed with new milkweed, you can supplement the diet of FIFTH INSTAR caterpillars (not the younger ones) with slices of cucumber or pumpkin/winter squash.

If you have to do this, just be sure you use organically-grown produce (no systemic pesticides) and scrub the heck out of them with soap and warm water BEFORE you cut into them. Organic growers often use a soil-borne bacterium called Bt (Bacillus thuringiensis) to control caterpillars on their crops, and this can just as easily kill Monarch caterpillars. 

Let us repeat: Monarch caterpillars should only be fed milkweed; other food sources should only be used temporarily during emergencies.  

What triggers Monarch butterflies to migrate? 

Monarch butterflies are triggered to produce a super generation and/or migrate by the following environmental cues:

• decreasing number of daylight hours, 
• cooling temperatures,
• decreasing quality of aging milkweed,
• decreasing nectar sources. 

How can you tell the difference between a male and female Monarch butterfly? 

The easiest way to distinguish between male and female Monarch butterflies is that the males have two distinctive black spots on their hind wings.

My Monarch’s wings are deformed and it can’t fly. What should I do? 

A common disease that effects Monarchs — especially in warmer climates — is OE (Ophryocystis elektroscirrha). This is a protozoan parasite that Monarch caterpillars get while eating milkweed. The parasite’s spores are then spread via infected to new plants and new butterflies via infected adult butterflies.

This is another reason it’s a good idea to move your adult Monarchs to a separate holding pen as they dry their wings, potentially preventing the spread of infection to your other caterpillars. Heavy OE infection in caterpillars is the main cause of wing deformity in emerging Monarch butterflies. 

If you have a Monarch butterfly whose wings are still crumpled and unable to fly a day after eclosing, you’ll want to euthanize it to prevent the spread of OE. Dispose of the body in the trash rather than outside. If you have an OE infection, you’ll also want to use more extreme cleaning methods of your hands, holding pen, etc to prevent its spread. 

How can you tell a “super generation” Monarch butterfly apart from other generations? 

The super generation of Monarchs usually starts in the north in late August. In our area (Greenville, South Carolina), it usually starts in early-mid September. 

In addition to the time of year, you can tell the super generation of adult Monarch butterflies by their wingspan. Most early generation Monarchs have a wingspan of 3.5 – 4″. The super generation has a larger wingspan over 4″.

What else can I do to help Monarchs? 

You can tag your Monarchs and report the data of other tagged Monarchs that you capture and release via the Monarch Watch Tagging Program. University of Michigan’s M3 Monarch Migration Study may have volunteer/citizen scientist opportunities as well.   

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We hope you enjoyed this guide to raising Monarch butterflies at home! If there’s a question we didn’t answer or you want to add some of your own tips, please let us know in the comments below! 

KIGI,

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