Transforming from Monarch Caterpillar to Chrysalis

Monarch caterpillar splitting skin to transform into a chrysalis

After munching their way through caterpillar life, it’s time for the magic of becoming a butterfly to happen in the chrysalis (the pupal stage). So how does the monarch caterpillar get inside the chrysalis? Let’s take a look at this major transformation stage in the monarch-friendly garden.

Preparing to Form a Chrysalis

When a mature caterpillar is ready to pupate, it will often journey away from the swan plants (or climb if enclosed) and look for a suitable place to transition. If possible, it’s better not to disturb the caterpillar or force them into a preferred pupating position – time and energy are ticking. The caterpillar attaches a wad of silk at its chosen location, spun from its head. It then fastens to this silk and dangles upside-down in a distinctive J shape while preparing to pupate. 

Monarch caterpillar dangling in a J from milkweed (swan plant) seed pod

I couldn’t get a photo of the silk pad on my cheeky little melon leaf caterpillar pictured elsewhere throughout this post (and in the follow-on butterfly post) without disturbing the plant. The different caterpillar pictured above decided to make a swan plant seed pod their dangling point. Crazy cats!

It wasn’t worth risking the safety of the melon caterpillar for a photo. It is very important that caterpillars not be moved or otherwise disturbed at this stage, if possible. Caterpillars who have gone into their dangling J in preparation for pupation may not be able to reattach after disturbance. This would, unfortunately, lead to an early death instead of ongoing transformation.  

The J stage is temperature dependant, and can range from approximately 8-36 hours. If you’re hoping to see a caterpillar pupate, watch for a limpening of the outer features like the antennae. Despite our many caterpillars, I’ve only occasionally had the opportunity to see the full process. If you’re keen, it’s worth the wait. Watching it happen is pretty amazing if you can catch it!

Transforming from Caterpillar to Chrysalis

Once the caterpillar is ready to pupate, the actually transformation from dangling J to chrysalis occurs quite quickly. The caterpillar splits and sheds its skin one final time, starting from the head and progressing down the back of the body, revealing the formed chrysalis beneath. It then does a wiggly little dance whilst dangling from its cremaster to shake free of the molted skin.

Monarch caterpillar splitting skin and transforming into a chrysalis

The newly formed chrysalis is soft and bumpy, with a pale greenish yellow colouration. Don’t panic! That’s normal immediately after transformation. 

The chrysalis gradually tightens into a smooth and more familiar form. The outer casing slowly dries and hardens, taking on a slightly darker green colour. Look at the different in the appearance of the same freshly formed chrysalis a few hours later! 

Monarch butterfly chrysalis

Monarch Chrysalis Care and Support

Monarch Chrysalis Care

Chrysalides require little care. There is no eating (or pooping…at last…) during this development. Shelter from extreme temperatures can help ensure the chrysalis remains viable. If conditions are hot and dry, it can be helpful to periodically lightly mist them to help maintain a natural moisture level.  If the chrysalis becomes too dry and hard, it can be difficult for the butterfly to eclose.

Moving Monarch Chrysalides

A freshly exposed chrysalis is very soft and fragile. As shown above, it then tightens into itself, dries, and hardens. If possible, allow this to happen before any movements. Monarch Butterfly Garden has good tips and photos for moving J caterpillars and chrysalides if you find yourself in urgent need.

I have a DIY “chrysalis palace” made from scrap plywood and mesh shade cloth to relocate or rescue fallen chrysalides. I rehang them securely below the mesh with dental floss. It also works well for taping in place if the chrysalis is on a leaf or branch. The structure is cheap, portable, easily cleaned, and works perfectly.  It feels great to see a rescue safely depart as a butterfly.

Sometimes a rescue is unavoidable, but I’ve managed to avoid many chrysalis movements by temporarily relocating the entire object to a safer position or by temporarily propping things up to allow sufficient free space around low-hanging or crowded chrysalides. 

Sometimes, the chrysalis is on a leaf that can’t be moved or propped. For those, if the leaf is still healthy and secure, I wait until a day or two before the butterfly will come out before moving the entire leaf with chrysalis still attached. The leaf can be taped securely is a safe position for opening, and waiting helps to ensure the leaf will hold together until the butterfly safely departs. If waiting isn’t possible or the leaf is compromised, a normal rescue with floss may be safer and more secure.

Monarch Development in Chrysalis

Similar to the caterpillar stage, the pupal stage lasts approximately two weeks, depending on conditions. If you’ve not seen a chrysalis before, they might look alarming small to eventually hold an entire butterfly, but they can (more on that in our next post!). The butterfly transformation occurs inside the chrysalis casing. It does not grow or expand. Tight quarters, indeed!

Transparent monarch chrysalis ready to eclose

When the transformation (metamorphosis) is nearing completion, the appearance of the chrysalis will start to darken and the butterfly inside becomes incrementally more visible until it can be clearly seen inside a now almost transparent casing. Butterfly time is near, stay tuned!

Transforming from Monarch Caterpillar to Chrysalis

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