Now that you’ve prepared to raise monarchs, these next steps take less time and allow you to enjoy this magical transformation as a curious spectator. You may be surprised to hear that rearing baby caterpillars is easy…but only if you have a good system in place.
From Egg to Caterpillar
Just before your eggs hatch, the top of each egg will turn dark. This is actually the caterpillar’s head about to make its grand entrance into the world.
However, if the egg turns completely dark, your caterpillar didn’t survive. This macro photography of a monarch egg shows an egg that has been parasitized by trichogramma wasps. The dark-spotted egg signifies the monarch embryo has been destroyed.
To the naked eye, this will appear as a completely dark egg.
If you have a dark egg, give it 48 hours to make sure it’s not a viable caterpillar. Then fold the egg inside the leaf and smash it with your fingers. Otherwise, in about 10 days a bunch of tiny wasps will emerge, mate, and start parasitizing more monarch eggs!
An unfertilized monarch egg will take on a different appearance. It will remain cream-colored, but…
A monarch female is more likely to lay unfertilized eggs at the beginning of the season when mates are scarce and at the very end when cool temps stop monarch mating cold in its tracks…
After your tiny caterpillars emerge their first meal will be their nutrient-rich shell.
Fun Fact: monarch caterpillars measure less than 1/10″ upon hatching.
Many of you will have a hard time seeing these tiny caterpillars, and that’s why its a good idea to have them in food containers where you can leave them until you can 👀 them…this is when your magnifying glass will come in handy!
Monarch Eggs on Leaf Pieces
As soon as a baby caterpillar hatches, remove it (on its leaf piece) and put it inside a second food storage container lined with a dry paper towel, and a large fresh milkweed leaf or leaves. Make sure these leaves have been thoroughly rinsed with water before serving.
Place a manageable number of caterpillars inside these new containers…I would suggest 4-6 caterpillars per container. You can discard discard the leaf pieces as the caterpillars desert them for the fresh food beneath. You might want to throw the deserted leaves in another food container labeled trash to insure you aren’t accidentally throwing out a tiny egg or baby caterpillar! 🐛 Check inside the trash container periodically for evidence of leaf munching, and perhaps a small HELP message written in milkweed sap 😉
For the next few days, check on your hatchlings daily and mist lightly over the leaves before closing the container. By misting lightly, I mean a couple short sprays from a spray bottle. Excess moisture can cause mold…
Monarch Eggs on Milkweed Cuttings & Plants
If your eggs are on cuttings or plants, the caterpillars will be fine to feed on those for days, and possibly up to a week! Here’s a caterpillar that is still feasting on the same cutting it was deposited by mother monarch:
Even though baby caterpillars are hard to 👀 on cuttings/plants, they’ll leave plenty of evidence that they’ve emerged and are starting to grow:
Water for Baby Caterpillars
If they aren’t inside a secure cage, odds are you will never find them and they will die of starvation. To avoid this tragedy:
1. Spray the plants while they are inside the cage or have cutting containers on a tray where you can easily see them if they fall
2. Mist the milkweed plants from above so water mist rains down on them. Spray up, and let the water fall down on to the plant.
There is still a slight chance they could fall but they will fall straight down instead of blasting sideways off your plant. They will be usually be hanging from a self-spun silk thread if they fall straight down, and can climb back up it….like mini marvel spider-men!
It’s a good idea to have single milkweed leaves on the cage floor in case caterpillars fall during spraying or wander from the plant. Keep the leaves slightly away from the cuttings/plants so they don’t collect falling frass. 💩
Changing the Cuttings
If your cuttings are taking up water properly they will last until they are (almost) completely devoured. I recommend placing another cuttings container by them in advance so caterpillars can crawl over when they need fresh food.
By the time they are done with their first cuttings or potted plants, they should be at least instar 2 caterpillars (3/10″) and easier to see than the mini-monarchs that hatched just days earlier.
Cuttings Tip: prepare your cuttings the night before you plan to use them to make sure they are taking in water. Once you become skilled with cuttings, you can take them as you use them.
Picking Up Baby Caterpillars?
When transferring caterpillars from your food containers, cut off a small leaf piece with a caterpillar, and place it on a new plant or cutting like this…
Small caterpillars on plants/cuttings should have no problems crawling to new cuttings. Just place their current container or pot next to a new one. You can also place a small pot inside a larger one:
If the cats are having issues finding the new food supply, some raisers have reported success moving them over with a soft-bristle paint brush. Community member Carolyn M. reminded me, you can usually coax them to crawl on the tip or side of a milkweed leaf.
That being said, monarchs have been going through this amazing metamorphosis for centuries. If you give them some time, and a little wiggle room, they can usually figure things out on their own…
Please read through the comments below for more info. Then scroll to the bottom of the page to post Unanswered Questions or Comments about Caring for Baby Caterpillars.