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  • Writer's pictureJessica Morgan McAtee

Cue the Chrysalis

It is amazing to witness a butterfly making her chrysalis.

But first vocab. Butterflies don't usually make cocoons, though some species do. Typically moths make cocoons. Cocoons are not the same as Chrysalises. The pupa form of a butterfly is called a chrysalis. The plural of chrysalis is chrysalids or chrysalides or chrysalises. The plural of pupa is pupae. Other insects like bees, wasps and beetles make pupae but only butterfly pupae are called chrysalises.

We can correctly refer to stage three of the butterfly life-cyle as either a pupa or a chrysalis.

Caterpillars initiate the visible parts of this process after they have had their fill of terrestrial living as a lowly juvenile on host plants and are ready to take on their next phase in life. It is triggered by hormones and not a spiritual awakening as far as we know.

Truthfully, the changes are increasingly taking place internally in the larva as juvenile hormones become less and adult hormones become greater.

Juvenile Hormone (JH) is what keeps insects from adulthood. They cannot reproduce as juveniles so it is imperative for species survival that they become mature. At the molt that reveals a pupa, there is no more JH, which means grown-up life will kick-in.

It will trigger a complete metamorphosis.

It's hazardous and quite a gamble.

Yet it's the ace for the win of a brilliant total make-over.

In preparation, the caterpillar eats less and can remain still for long periods of time. Some, like Swallowtails, purge their guts, which is absolutely as grotesque, disgusting and stinky as it sounds.

Some caterpillars will make a chrysalis directly on their host plant. Most wander off within an area of 30 feet or less to make their magic. Some make it in the dirt or in loose leaf litter. Often this preference is largely determined by species.

Those that wander off in the wild may end up on another plant, leaf, dead tree or branch. Those in our gardens may end up on the fence, hose, lawn furniture or other inconvenient place. I've had them in treacherous locations like the wheel wells of my car, garbage can handles and the underside of an open awning window.

Caterpillars have a spinneret gland below their mouths that produces silk.

When making silk, they move their heads from side to side to make an effective silk ladder to climb on. This helps them in their younger stages by allowing them to adhere to slick leaf surfaces.

In their more mature stages this life skill aides them in different ways.

Swallowtail (Papilionidae), Sulphur (Pieridae) and Brushfooted (Nymphalidae) butterflies make a chrysalis with the use of a cremaster at the tail end of their bodies. It is the hindlegs of these caterpillars that are transformed into the cremaster. Just before the change, the prepupal caterpillar has to perform the fantastic feat of hooking that rear cremaster into a tangled pad of pre-spun silk that it spent its final caterpillar hours weaving.

There is a strong concentrated amount of silk in the center of the pad and this is where it will attach to hang from a substrate.

Brushfooted types, like Monarchs, hang head-down from the sturdy silk mat in the shape of a "J".

After many hours of suspension, the caterpillar prepares to molt its skin. It will have to disconnect, remove the skin and then reconnect to the pad. This occurs all in one fell swoop of danger. The cremaster sticks like Velcro and as the larva writhes around the silk becomes microscopically entangled and attached to the cremaster.

If you look closely, you can see the many tiny cremaster hooks that are fettered to the silk on this Monarch pupa.

The molt into a chrysalis is violent and unrehearsed.

Every molt is a substantial risk for an insect, but this one is especially perilous because of the acrobatics involved.

If all goes well, the old caterpillar suit falls to the ground and the newly attached chrysalis proceeds to harden, or dry, in the proper shape that will form the mold of the future butterfly.

At first it looks like a shiny wet alien form, but within an hour or so it will settle into its appropriate shape.

Gossamer-winged (Lycaenidae) butterflies don't have a cremaster, so they either pupate in the ground or loosely attach themselves with silk. By loosely, I mean barely.

Atalas are constantly coming detached from their silky hot mess like the one dangling in the far left of the photo.

Brushfoot butterfly chrysalides are attached at one place only.

But others prefer more security than that.

Caterpillars in the Sulphur and Swallowtail families attach themselves with a second string of silk that girdles their midsection. Effectively, they are attached at their tail end and also with a belt-like thread near their thorax closer to their heads. They opt out of the singly attached "J" shape for more of a hammock posture.

Note the before and after for this Polydamas Swallowtail and check-out the silk belt in both.

Within the chrysalis, the disintegrating caterpillar essentially liquefies. This bizarre process involves dissolving the previous body and simultaneously building a new one. Most of the old materials are reused, upcycled or repurposed for the new and improved form. The cells are redirected and reintegrated to make a totally different phenotype.

Almost nothing is wasted.

A freshly formed pupa is delicate like a water-balloon and if it falls it won't be pretty.

The finer details of this process remain a scientific mystery.

In warmer climates or summer the chrysalis stage may take two weeks or less. They emerge within some constraints when environmental conditions are favorable. However, in colder climates, butterflies may overwinter as a chrysalis. Their development is stopped by a state called diapause which is similar to hibernation. They will wait to emerge in spring when environmental conditions are more favorable.

Each butterfly species makes a unique chrysalis. Related ones can look very similar, but experts can tell them apart.

Chrysalises are alive and breathing, just like all other stages of the insect's life. They breathe slowly through spiracles, holes on the thorax and abdomen.

Some chrysalises remain still while anchored into their substrate but others can wiggle around. Some can make sounds. These strategies along with cryptic coloration and secret hiding spots are all intended to fool or scare predators.

If you look at a chrysalis, you can distinguish the wings, antennae, head, eyes, legs and other parts. In many species, this is especially true just before emergence as the folded- up butterfly is visible through the thin pupa shell.

This Ruddy Daggerwing is just about to erupt. Erupt isn't a technical term but my niece used it and I find it fitting.

Sometimes a chrysalis becomes detached from its silk pad.

All is not lost, check out my video about reattaching a chrysalis.

Geesh that was geeky.

Since your mind is probably blown, I'll give you a breather.

Jessica Morgan McAtee

156 views2 comments


Aug 20, 2020

Any idea why several Monarch caterpillars cremaster break off after attaching to the silk pad? Seems to be happening to a few people who are raising Monarchs. No one seems to know the answer. Any ideas are much appreciated in solving this mystery.

Debbie Silva-Romero
Debbie Silva-Romero
Apr 24, 2022
Replying to

I’m looking for the exact answer! Is there something we can do to help?


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