How to Care for a Monarch Caterpillar

If you are one of the lucky ones who found themselves caring for a cute little eight-legged fuzzy friend, otherwise known as a monarch caterpillar, you probably fall into one of two categories. Either you have never been a foster caterpillar mom before, or you could use a quick refresher course. Hopefully, this post will take care of both!

I will go step-by-step through the life cycle of the monarch and you can just jump in wherever you happen to be with your new temporary family member.

Finding eggs:
Eggs can be found on the underside (almost always) of the milkweed plant. Unfortunately, milkweed is becoming harder to find as more and more houses and building are being built and as more heavy duty pesticides are being used in fields and pastures. It is a weed, so it is usually found along the sides of roads and pastures, along fences...those kinds of places. There are LOTS of different varieties of milkweed, the most common in this region (Utah) being Common Milkweed. If you tear the leaf, you will see, yep, you guessed it, milk. Ok, so it isn't really actual milk that you drink wouldn't that be cool?, but it sure looks like it!

Here is an egg on the underside of a milkweed leaf. You can see some of the milk on the leaf below it.

Monarchs only eat milkweed. The milky substance in it makes them taste bitter so it acts like a natural deterrent to predators.

If you find an egg, it will only be an egg for a four to six days before it will hatch. Watch the egg, when it starts to get black on the top, it is getting ready to hatch. If you are lucky, you will see it wiggle its way out of the egg and start its journey as a hungry, hungry caterpillar. A newly hatched caterpillar is super, super tiny. It is actually kind of hard to see it is so small. But....they will grow and grow really quick!

The Hungry, Hungry Caterpillar:
Once your wiggly friend had taken its first breath, all it will do is eat and eat! It will eat its own weight in milkweed in one day. This stage only lasts 9-14 days. It is fully grown at about 2". At that point it will likely wander, searching for a place to settle and form its chrysalis. During this caterpillar stage, you will need to keep a fresh stalk of milkweed for your caterpillar to be munching on. Keep your milkweed in a jar of water to keep it fresh, a mason jar works great. I keep the lid and ring on it and just poke a hole in the lid big enough to stick the milkweed through. When the leaves start to get dry or just old looking, get a new stalk. The bigger your caterpillar gets, the more it will eat and the faster you will need to replenish your milkweed. This is their only source of food, so make sure you are watching to make sure your caterpillar always has something to eat, and something to crawl on. Your caterpillar will shed its skin five times. Like a snake, you will see the skin after it is shed. Kinda gross, kinda cool.

Before getting too close to the end of this stage, make sure your friend has adequate housing. So far all they are doing is eating and will most likely stay on the milkweed, munching away. But, when the caterpillar stage ends, they WILL wander off, looking for the perfect spot to settle down. We have found our caterpillars on our kitchen counters before, and even have had them attach and form their chrysalis under counter tops. Definitely a conversation starter, but not really something I would advise.

In the past I went to the local thrift store and found a huge glass vase. I have also used a fish bowl. It needs to be large enough to fit your jar of water with your milkweed stalk inside. Cover the top with some kind of netting. I think I used tulle for mine. We are now the proud owners of a 'butterfly house' that is super tall and awesome and works great. But.....some kind of large glass vase or bowl will work fine, too!

Our fancy, dancy butterfly houses. We just stick  the jar and milkweed right inside.

Chrysalis:
When your caterpillar is full grown (about 2 inches), it will find a spot to 'form a J'. He will find a place, usually not on the milkweed, make a little silk-like mat and attach itself to it, hanging upside down in the shape of the letter "J". It will stay this way for about one full day.

At this time, your friend will shed it skin for the fifth and last time, but instead of a new layer of caterpillar skin underneath, it will be a jade green casing, or chrysalis.

The chrysalis is only about an inch long and is soft at first. After about an hour it becomes a hard protective shell. It will stay in its chrysalis for 9-14 days. After its transformation inside the chrysalis is complete, the shell will become clear. You will be able to see the black and orange wings stuffed inside. When it is ready, the butterfly will break out of the chrysalis. Its wings will be wet and crumply and it can't fly yet. It will hang onto the chrysalis while a blood-like liquid is pumped through its body. This will make its wings and body bigger. About an hour after it emerges from its chrysalis, its wings and body will be full size, dry and all ready to fly.

At this time, look on the top of its wings (looking down on to the top of the butterfly) when they are opened up. If you see a black dot on both wings (on the bottom end, not the head end) your butterfly is a male. No spots, you have a girl. Here is a good picture to show you what to look for.

Now....take your winged creature outside, wish it well and send it on its way!


If you would like to follow our own caterpillar journey, or see more pictures, you can go here.
Also, here is a post I did about the life cycle of a monarch butterfly in more detail.