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.
Caring for Baby Caterpillars
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…
Monarch Eggs on Milkweed Cuttings?
If your eggs are on steam or leaf cuttings, the caterpillars will be fine to feed on those for days, and possibly more than a week! Here’s a caterpillar that is still feasting on the same cutting it was deposited by mother monarch:
Monarch Eggs on Leaf Pieces?
As soon as the top of the eggs show even a hint of darkness, put them on top of a single milkweed leaf or or stem cutting. Put each egg on its own leaf to prevent a baby caterpillar munching on a neighbor’s egg.
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 on milkweed cuttings (or potted plants) where you can leave them until you can see them…this is when your magnifying glass will come in handy!
Even if you can’t see your baby monarchs, they’ll leave plenty of evidence that they’ve emerged and are starting to grow:
If they aren’t inside a secure mesh 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 them 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 (remember to nick the sides to increase water entry points) they will last until the leaves, flowers, and milkweed pods are completely devoured. I recommend placing another cuttings container by them in advance so they 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.
Picking Up Baby Caterpillars?
Small caterpillars 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:
For caterpillars on single leaves, cut off a small leaf piece, and place it on a new plant or cutting like this…
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…
Coming Up Next
Cage cleaning….your monarchs’ lives depend on it!
Please Read the Comments Section below for more info about Baby Monarch Caterpillars.