Monarchs live and grow according to their own schedule. But sometimes we need to manipulate them, so they conform to our calendar. Here are some techniques for timing of...
- Egg production,
- Butterfly emergence, and
- Chrysalid emergence from the "J."
Timing to produce eggs when schools start in the fall
Elementary schools typically start around September 1, give or take a few days. Most teachers want tiny caterpillars during the first days of classes, to calm squirrely students. But wild monarchs stop laying around the end of August.
Method 1: Capture females in the wild starting August 15-20.
This is the easiest method. It takes a few days to capture the females, then a few more for them to become tame and learn to feed in captivity and begin to lay eggs. This method succeeded in 2022 and 2023. But in 2024, I couldn't find enough females because there were fewer monarchs. I had to advertise on the internet for neighbors who could give me chrysalids. Someone gave me eight, from which emerged 3 females. The uncertainty of this method required a backup...
Method 2: Raise your own laying females from eggs.
You either find eggs in the wild or capture wild females that lay eggs--then raise the eggs to produce females. Mate the females with wild-caught males (since males are much easier to catch than females). This method requires attention to detail if you want to have eggs for the start of classes.
Below is a table of the number of days in each stage of the life cycle. I show a range of days, primarily because of temperature differences. Lower temperatures slow monarch development, especially in late summer when nights are cool.
- Egg 4 -5
- Caterpillar 10-14
- "J" 1 -1
- Chrysalis 11-12
- Total so far 26-32 Time from laying to eclosure. Select 27 as best estimate.
- Laying 3 -8 Time from eclosure to start of laying. Select 5 as best estimate.
- Total time 29-40 days
Some authors report longer times, but because I raise monarchs indoors until eclosure, where night-time temperatures are warmer than outdoors, my times tend to be shorter. Therefore, I'm going to select 27 as the best estimate of time from date laid to eclosure, and 5 as the best estimate for time from eclosure to start of laying. Combining the estimates: 27+5=32 days. Use your own records to improve these estimates.
Next, draw up a calendar. Mark on the calendar dates when various batches of eggs were laid, then count out 32 days and enter these dates as the times you expect to get eggs. Click on the image to enlarge it.
Timing eclosure
The biggest event for students in the monarch's life cycle is emergence of the butterfly. What a shame if they should miss it because the butterfly emerges before the students arrive. And this often happens, because monarchs emerge as soon as they see bright light in the morning. Here's
a link to a method for controlling the time of eclosure.
Watching a caterpillar change to the "J"
Watching a caterpillar wriggle out of its old skin to reveal the green chrysalid underneath is a magical moment, nearly equal to watching the butterfly emerge.
I'm not aware of any way to affect the timing of "J" formation, though I suspect cooling the caterpillar would delay it. So, it's better to try to predict when it will happen, then watch for it.
In preparation to forming the "J," the caterpillar spins a disk of silk which it then grabs with its hind legs, then hangs from the hind legs. The disk has many loops of silk on it. The disk is much larger than it appears, since the edges are thin and nearly invisible. It has a broad base of attachment. The caterpillar remains in the "J" for 10-12 hours. If you add the time the caterpillar needs to find a good, elevated spot and spin the disk, the overall transition time is about 24 hours.
Once it begins to hang, the front antennae slowly begin to shrivel and become twisted. Once they become very much so, it's about half an hour to forming the chrysalid. If you have someone in the class watch the "J" carefully, he or she can notify the class when the split along the back begins. Quick! There's no time to lose! Get ready to watch.
It happens in just a few minutes, during which the caterpillar's skin splits along the back. It's the hind legs of this old skin that's clinging to the silk.
Once the split in the skin gets long and wide enough, the caterpillars wriggles so the skin moves toward its hind legs. Now, keep in mind that the only thing preventing the caterpillar from dropping to the ground is the grip of its two hind legs--which are part of the skin it is shedding. The chrysalid which will emerge is not attached to anything at this point. Somehow, the caterpillar has to shift its attachment from its hind legs to the "cremaster" on the chrysalid.
The cremaster is a hard "pegleg" with many tiny barbs on its tip. As the skin slips off the chrysalid to reveal the cremaster, the chrysalid suddenly jabs the cremaster into the silk pad, and twists vigorously this way and that, so as to firmly insert and tangle the barbs of the cremaster into the loops of the pad. Once inserted, the chrysalid continues to twist and move until the old skin drops to the floor.
The movements slowly decrease, while the longish chrysalid gradually draws into a more compact oval shape and hardens. Further change occurs over days, as golden spots appear along with the buds of wings. Most of the tissue making up the caterpillar liquifies, then transforms into butterfly tissue.
This amazing switch of attachment points reminds me of a famous performance of Houdini. He was hanging from a hook outside the fourth floor of a building. The hook was attached to a straitjacket that completely immobilized Houdini by confining his arms, crisscrossed over his chest. In those days they were commonly used to subdue violent patients in insane asylums. Houdini's trick was to wriggle out of the straitjacket and somehow grab the hook, without falling to his death below--the same act performed by every monarch.
More facts about chrysalids... If you drop one on the floor, it will shatter like an egg. If you break its skin, it will ooze green fluid. If it loses too much green goo, it will die. But it can heal and become a butterfly if it loses only a little green protoplasm. One of the things the "J" does while hanging is excrete all the frass from its digestive system. Consider: Inside the chrysalid, the digestive system is completely dissolved and transformed. Any remaining frass would be liberated to mix with all the other green goo, contaminating it.
