Feeding Monarch Caterpillars – 7 Essential and Easy Steps

We all step in to help raise Monarchs for their success, excitement and fulfillment, and the beauty of their transformation. Yet if we aren’t feeding Monarch caterpillars with wisdom, we are failing them. Here are the 7 essential and easy steps I take for ultimate success in raising the iconic Monarch butterfly.

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1. Know your limit

I had to learn this the hard way, my limit.

When I first started raising Monarchs, I collected eggs and babies from every single milkweed plant on my property.

Next thing I knew, feeding Monarch caterpillars was nearly a full-time job. Although it was exciting, I was overwhelmed at times. It would literally take me hours a day to clean habitats, ask questions, collect fresh milkweed, and keep my Monarch cats happy. (Cat is a term we lovingly call the caterpillars)

I raised hundreds the first year and spent a lot of panic-money on new habitats and floral tubes to accommodate my growing population. I even got creative and used an old cylinder fish tank and cut-up pantyhose for the top for a few older cats.

I learned a lot, I spent a lot, I saved a lot, and I was constantly feeding Monarch caterpillars, haha!

My biggest suggestion to you is to never overpopulate your habitats or take in more than you can feed or take care of properly.

Cleanliness is a MUST, and so is keeping smaller caterpillars away from bigger ones, so they don’t accidentally get eaten.

If habitats and milkweed aren’t kept clean, diseases can spread, and then we are harming the population.

If your Monarch cats aren’t getting enough milkweed, they won’t grow big and strong, and again, we are only harming the population.

So know your limits and start with a few. I promise you that it will only benefit them, keep you from feeding Monarch caterpillars almost all day long, and keep it fun for you.

I now only rescue the eggs and babies from the milkweed growing in my pastures, so my horses don’t step on them. The rest are growing naturally in my ditches, and the milkweed I grow in my flower gardens.

2. Finding milkweed

I understand the desperate search for milkweed when you have hungry Monarch cats. Your own supply is getting low, and you wonder where the next meals will come from.

I would start collecting milkweed from the pasture, then move on to the ditch or fields. That first couple of years made me a little nervous when it seemed my supply was dwindling.

I started looking at farm fields when I drove by but never collected.

Here’s why you don’t want to collect from farm fields unless it’s an organic farm, the milkweed growing there probably has pesticide or herbicide residue on it. So any caterpillar that eats it may either die or not grow properly.

It might look like it’s growing good, but chances are, it’s harmful.

I’ve also heard sad stories of people losing all of their cats after feeding Monarch caterpillars milkweed bought from greenhouses or garden centers.

This is because most garden centers put some kind of pesticides or other harmful chemicals on what they grow, so they look perfectly beautiful to the customer.

It’s important to find a reputable source in your area that doesn’t use these harmful chemicals on their plants before you buy your supply. Simply ask, they have to tell you.

Then, of course, it’s wise to ask before you take milkweed out of some random ditch or yard. You don’t know if they too have sprayed or used chemicals, and really, you just should ask.

I say that because I recently noticed the tops of some of my tall ditch milkweed cut off. I know rabbits and deer can eat milkweed, and we have plenty of both, but there weren’t any traces of animal tracks into the ditch. Not to mention the milkweed is older and not as tender, so they usually won’t eat it.

I know feeding Monarch caterpillars can be overwhelming. I’m all for helping out and helping the population, but don’t just take people’s milkweed without asking.

Finally, look for healthy milkweed! There is a whole life cycle living on a milkweed plant. So check for predators you may need to brush off (or leave to find the next plant), and check for other eggs. If you find any, just leave them be and move on to the next plant. Those eggs are often from ladybugs or Tussock caterpillars.

If I see yellowing leaves, black spots, or if the plant looks tough, I move on and look for a healthier, younger-looking plant.

Also, plant more milkweed that is native for your area to make feeding Monarch caterpillars easier. This will also help all Monarchs and other pollinators!

3. How to harvest milkweed for caterpillars

When my cats are very small, I usually replace their milkweed one leaf at a time.

I make sure nothing else is on the leaf before cutting it. I then use my little, sharp “mustache scissors” and cut the leaf at the stem, placing it in some water right away.

One thing to know about tiny Monarch cats is that they will rarely stop eating from their current leaf to the fresh one. I’ve had to literally cut the leaf all around them (obviously not too close as to harm them!) when they are 1-2 instar and place them on the new leaf.

I place a damp paper towel on the bottom of a Tupperware container and fold a part of it over on the stem portion of the leaf, making sure that part has a little extra water on it.

I place the leaf on an angle, so it’s resting on the container’s side, so the leaf doesn’t start molding. Mold will kill your cats!

The older caterpillars will usually crawl to a new leaf by themselves. But at about 3 instar, I usually cut a small part of a milkweed plant (5-6 leaves worth) while feeding Monarch caterpillars of this age.

I check them for other creatures before cutting and place them into my cup of water. I will then take it in and rinse the cutting off.

This removes any dust, dirt, or harmful predators you may have missed. I’m always careful not to wash off any unseen Monarch cats, though! These cuttings go into a large floral tube and into a stand made for the tubes.

This allows the cutting to be watered for a couple days or so and allows it to stay fresh with minimal handling.

When cutting larger amounts, it’s important to only cut what you think you’ll need if you don’t have large amounts of milkweed. Even more important to cut enough for your cats to eat.

Nothing worse than coming home or waking up to see the leaves gone while your caterpillars are hungry, looking for fresh milkweed.

I also make sure I cut healthy pieces, and I never cut the flowers or seed pods to take away seeds for next year. We need more milkweed in this world! 🙂

4. How to keep milkweed

As already mentioned, when feeding Monarch caterpillars, it’s important to keep the leaves or cuttings watered. They’ll last longer.

I never allow a leaf to rest fully on a damp paper towel, no need for mold to start.

If it doesn’t work to prop my leaf, I still somehow make sure the bottom of the leaf is getting air, and try to keep it moistly moistened where the stem is.

My favorite way to keep cuttings is the floral tubes I mentioned. They are extremely easy, and those tube stands are lifesavers!

I have also used small mason jars filled with water for cuttings. It is super important to cover the top of the jar, though! The caterpillars will easily drown!

To do this, I just put plastic wrap tightly over the top and screw the metal ring on. Poke a tiny hole and place your cutting there.

Tip: If you use mason jars and plastic wrap for feeding Monarch caterpillars, make sure you trim the plastic’s edges. If you don’t, you may have Monarchs making their chrysalis on them. Haha, yes, for real.

5. When to replace milkweed for babies

This will take up the major portion of your time when you’re feeding Monarch caterpillars. Replacing old milkweed for fresh.

You’ll be able to see when it needs to be replaced. If you’re collecting leaves, they’ll start to curl in, dry up, or turn colors.

You really want to keep the milkweed fresh for your cats, for fresh food means a healthy Monarch butterfly someday.

Generally, for single leaves, it’s every other day or so (based off of one leaf per small cat), and for cuttings, it all depends on how many you have eating milkweed.

When they are about 4-5 instar, this is when feeding Monarch caterpillars can get crazy. They can go through a couple or few cuttings a day, depending on the amount you have.

Rule of thumb is to always make sure they have fresh milkweed. No way around that housekeeping rule for healthy Monarchs!

6. How to give fresh milkweed

This might seem like a silly tip, but you’d be surprised how nerve-racking giving fresh milkweed can be.

From my experience and seasoned Monarch raisers’ experience, I would advise just to leave the old leaf in the habitat when your cats are 1-2 instar. The exception would be a molded leaf. That must go!

The reason for this is that they are SO tiny, it’s easy to accidentally throw them away, or squish them. Either of these and the caterpillars are better off left outside!

I make sure I know exactly how many are in each habitat (I have less than the manufacturer recommends). If I see them all, I can throw the old leaves away.

It’s easier when they are older, but you still have to be careful not to squish them when grabbing old cuttings or leaves.

It’s also important to know that they will often crawl away to molt. The caterpillars could go on the side of a floral tube, under the Tupperware or mason jar where you’d grab, or the inside zipper of your habitat.

Checking and double-checking could save a life.

When changing floral tubes, I just add the new cutting and leave the old. Unless it’s completely eaten down, you never know who is hiding in the old leaves. They could be molting or resting unseen.

They will naturally move over to the fresh milkweed, and you can then take the old stuff out.

Please note to always wash your hands after handling milkweed. The “milk” can irritate your eyes!

7. Things to keep an eye on

I go a little more in-depth for general care for raising Monarchs in other articles, as this one is directed to feeding Monarch caterpillars.

I do want to include some things to be on the lookout for, though, when you are feeding them.

It’s a good idea to have extra habitats for caterpillars you want to quarantine or keep away from others to observe.

For example, if one starts acting strangely or doesn’t seem to be eating or growing, it could be parasitized or diseased. You’ll want this one far from the healthy cats.

Don’t give up on those, though, unless the ailment is obvious. I’ve had some in question that did very well and never exhibited a single issue, turning into a beautiful butterfly.

When feeding Monarch caterpillars, you’ll want to keep your eye on leaf quality. I know I talked about this, but you’d be surprised how quickly a leaf or cutting can turn bad. You’ll see brown or black spots, faded leaves, or curled, wilting leaves. Bring in the fresh stuff if you do!

Caterpillars are wanderers, so please make sure you have proper Monarch habitats for them. The tiny mesh in these habitats keeps the tiny cats in and predators out.

I also like to keep my habitats outside in a dappled shady area during the day to be in their natural habitat. I bring them in at night or during storms. This keeps them healthy and considers the possibility that they are better migrators if raised outside.

Please keep the poop out of the habitat! To do this, I change the paper towels every-to-every-other day. If I’m using floral tubes, I get a damp paper towel and scoop them up from the bottom of the habitat that way. Obviously, the safety of the caterpillar is #1 when cleaning.

And please, do not handle them! This stresses them out and is unnecessary.

There are several things you can do to make this experience fun for you, yet super safe and effective for your Monarch cats. These are just a few.

Also, please know that we all have our own routines and ways to successfully raise Monarchs, even feeding Monarch caterpillars varies, I’m sure.

What matters is the cleanliness and quality of your Monarch’s home, and that you do what works for both you and your cats.

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Do you have any other questions or concerns about feeding Monarch caterpillars? Please drop them in the comments below, and I’ll try to address them. I hope this has been helpful, and thank you for helping this beautiful butterfly!