What is a cocoon?

Silk moth cocoons

What is a cocoon? A cocoon is the silk ‘sleeping bag’ some species of moths make before they pupate. A caterpillar creates the silken cocoon with a silk gland/spinneret that is located under its mouth. Butterfly caterpillars do not make cocoons. (Some people consider the nest that a few species of butterflies make before pupating – a cocoon.)

Polyphemus moth cocoon

Not all species of moths make cocoons. Some pupate in leaf litter and some pupate under the soil. Some make a leaf nest, not a ‘cocoon’ as most of us think of a cocoon.

A Tersa Sphinx Moth pupa, dug up from the top layer of soil near a pentas plant

All butterflies and moths go through four stages. Ova (egg), larva (caterpillar), pupa (pupa or chrysalis), and imago (adult. A moth pupa is called a pupa (singular = pupa and plural = pupae). A butterfly pupa is correctly called either a pupa or a chrysalis. A butterfly pupa/chrysalis is not called a cocoon. A moth pupa is not called a chrysalis.

Gulf Fritillary butterfly chrysalis

Cocoons that are used to make silk material contain about four thousand feet of one long silk strand.

It does not harm the pupa to cut the cocoon open and remove it, as long as the pupa is protected from predators and dehydration. If it is removed, it should be placed in a container where it can emerge and climb high to expand its wings.

A freshly pupated silk moth pupa was removed from its cocoon

Inside the cocoon is the moth pupa. Once the cocoon is finished, the caterpillar takes about three days to pupate. Changing from moth caterpillar to pupa is a longer process than changing from a butterfly caterpillar to chrysalis. Butterflies usually pupate within 24 hours.

A Cecropia moth caterpillar makes its cocoon

Butterflies and moths both pupate from caterpillar to pupa. A butterfly pupa is often called a chrysalis.

Red Admiral butterfly

Red Admiral Butterfly
Red Admiral Butterfly – Vanessa atalanta Red Admiral Butterflies are found during the winter months in Florida. They prefer cooler weather, laying eggs on Pellitory and False Nettle around our area. They also lay on stinging nettles around the United States. We definitely prefer False Nettle to the stinging nettles!


In the above image, you can see where Red Admiral Butterfly  caterpillars have created a ‘tent’ out of host plant leaves. Look for these tents while searching for caterpillars in the wild.



At the farm, we feed them a mixture of False Nettle and Pellitory, depending on the time of year and what is most readily available. Pellitory only grows in the cooler months for us, seeds germinating and sprouting in the fall, dying back once the weather gets hot again in late spring. During the warmer months we use False Nettle.Read below to follow us as we care for our Red Admiral Butterfly caterpillars in the lab here at Shady Oak Butterfly Farm.
We start with eggs laid by our breeder butterflies. This image is of Red Admiral eggs on False Nettle. In the wild, you will not find a large number of eggs on a single plant, this is only the result of several adult females in an enclosure with one host plant provided.


We keep the plant in a mesh habitat and water it daily while waiting for the eggs to hatch. False Nettle requires a great deal of water, and will even grow in standing water along rivers and in ditches in the wild.


It is easy to tell when the eggs have hatched! The caterpillars will eat quickly and the leaves become skeletonized.
The small black caterpillars will soon be seen sitting on the leaves. These caterpillars are around 1 week old. When first hatched they are very difficult to see due to their tiny size. At this point, we transfer the caterpillars to cups.


Here you see a handful of Pellitory we have gathered to feed the caterpillars. They will not need many leaves at first, but as they grow their host plant needs grow with them!


Here is a tote of cups, each holding one Red Admiral caterpillar. You can see that most have eaten all the food provided from previous day. The cups on the bottom left have already pupated and the chrysalises were left to harden overnight before removing them from the cups.


The cup on the left in this image still has green leaves left, which is a clue to me that the caterpillar may be done eating during the larval stage and is ready to pupate!


Another image of the cup from the side. Plenty of leaves left, but no sign of a caterpillar on the lid – I will need to open the cup to investigate further.


Still no sign of the caterpillar…


Ah-hah! Found him. Red Admirals love to form their chrysalises inside a small ‘tent’ of host plant material. We always have to keep that in mind while removing old leaves from cups and habitats.


The chrysalis has hardened and is ready to be removed and taken into our pupae room. We do not keep chrysalises in the same room as caterpillars.


Here are a few more chrysalises that were removed and taken to another room. This batch will be used as breeders. The next batch of caterpillars will be ready to ship out in a few weeks. 


Once the butterfly has fully formed and is ready to emerge from the chrysalis, you will see the wings through the chrysalis cuticle. This butterfly will emerge within the next 24 hours. We will have Red Admiral Butterfly caterpillars available in a few weeks, reserve yours today! They are available for pre-order on this page. Are you interested in adding Red Admiral Butterfly Host Plants to your butterfly garden? False Nettle – Bohemeria cylindrica and Pellitory – Parietaria floridana 

What killed my caterpillars?

When we’re raising caterpillars in our homes, we are fighting nature. Nature has a goal of killing 98% of them before they become adult butterflies. The odds are stacked against us before we even bring a caterpillar from our garden to our home.

Nature uses disease as one method to keep a butterfly species alive while killing most caterpillars.

Gulf Fritillary caterpillar died from Nuclear Polyhedrosis Virus (NPV)

NPV – Nuclear Polyhedrosis Virus – is one of the worst diseases. One caterpillar can have a billion virus particles in its body. The virus causes caterpillars to crawl upward before they die. The caterpillar or chrysalis turns to liquid and the virus particles drip and splash, covering a large area as it rains or we water or gardens. Another caterpillar needs only to eat a leaf with invisible virus particles on it and it will soon die of the disease too.

Monarch with anal prolapse
Gulf Fritillary with anal prolapse

Anal prolapse may happen naturally. It can also be caused by exposure to some pesticides. The digestive tract begins to come out of the caterpillar’s anus. When this happens, the caterpillar will die.

A Monarch chrysalis failed to finish forming and sealing properly

It is natural for a chrysalis to be deformed or fail to finish forming properly. It shouldn’t happen often. If it happens to more than a couple at a time, chances are that they have been exposed to a pesticide. Some pesticides cause failure to pupate.

Monarch caterpillars quit eating due to Bt (Bacillus thuringiensis) bacteria ingestion

Bt is a natural soil-dwelling bacteria. When caterpillars take a bite of food that includes Bt, its gut lining begins to break down and it stops eating. Three days later, the caterpillars die. One of the first signs of Bt ingestion is what you see in the photo above. Caterpillars had been given fresh food 18 hours earlier and didn’t eat more than a couple of bites

Dehydrated Red Admiral and Julia chrysalises

Chrysalises can dehydrate if they are in a dry area. In nature, they usually have plenty of humidity from the plants around it. In captivity, they sometimes die from lack of humidity. The butterflies fully form yet die before emerging. The tell-tell sign is that chrysalises are light as a cotton ball and when broken open, they are dry inside.

A deadly fungus kills a moth caterpillar

Fungi kills caterpillars, chrysalises, and adult moths and butterflies. When you touch caterpillars or their food, always wash well first. It is easy to track/carry spores with you as you touch a plant in nature with the spores before picking food for your caterpillars.

Bright green spit/vomit from pesticide exposure

Caterpillars that are exposed to certain pesticides will spit or vomit green liquid. Some spit green as a defensive mechanism. In time, you’ll learn which naturally spit green when touched and which are reacting to pesticide exposure. Spit/vomit stays green. Hemolymph (like blood) that drips from a caterpillar or chrysalis will turn black or gray within five minutes.

Monarch caterpillars abnormally colored

One of the signs of disease is abnormal coloration of caterpillars. Sometimes the abnormal color is natural, from cooler weather or genetics, but sometimes it is from disease.

Bacteria can cause abnormal coloration of pupae, such as with these three Monarch pupae

There are many signs that you can see from bacterial infection. An abnormal color of caterpillars or chrysalises can be caused by bacterial infection.

Improper molt of a Monarch caterpillar

Caterpillars should do a complete molt, their cuticles coming off in one piece. When a molt looks like this, it is a sign of other problems, disease or even a too-dry environment.

OE infected Monarch butterfly

OE (Ophryocystis elektroscirrha) is a protozoan parasite that infects Monarch, Queen, and other species that host on milkweed. In the photo above, we see the discolored abdomen and crumpled wings, classic signs of OE. The adult butterfly is often sticky with a darker than normal abdomen. Quite often, in the worst cases, adult butterflies cannot get out of their chrysalis shells.

What can you do? Use caution. Stay clean. Clean the rearing area well. Disinfect rearing containers between every generation of caterpillars. Check every milkweed-eating butterfly for OE spores. Avoid pesticides. When purchasing host plants, ask if they have been treated for plant pests and be aware that the retail nursery may not have been told if the wholesale nursery has treated the plants earlier. Remember that organic pesticides are as deadly as inorganic pesticides – both are created to kill plant pests.

Jonathan found a Gulf Fritillary caterpillar in the garden

Be aware that when you bring in a caterpillar, it may already have had a death sentence and you can do nothing about it. Focus on the butterflies and moths that you raise successfully.

Thank you all for what YOU do for butterflies!

Orientation of Attaching to Pupate

Why do caterpillars tend to attach with their legs toward the light? Or do they?

We noticed that most of the Monarch chrysalises in our lab were oriented with their legs to the light. We did a test to see if this was right. Was it our imagination? We selected four containers with Monarch caterpillars and placed them in specific spots in the room, on opposite walls, to determine whether this was so. Each container was marked and placed in the exact same spot, level, and position each day.

Containers of Monarch butterfly caterpillars in the lab, fed daily, removed when they became chrysalises, and were then shipped to exhibits throughout the US.

In each container, Monarch caterpillars were housed and fed fresh milkweed daily.

Monarch caterpillars and chrysalises in the lab.

Out of 30 chrysalises in each container, only two or three attached with their backs to the light. Most were angled with their legs more to the light than to the back.

Nearly all the Monarch chrysalises had pupated with their legs toward the light.

More studies need to be done by others to see if this proves true in all areas. Our one study does not make a definitive scientific conclusion other than, in our lab, they pupated with that orientation.

If this position is an advantage, why? We believe that pupating with their legs toward a solid object, as they pupate on in nature at times, can cause life-threatening damage to the finished chrysalis. When attaching to a fence, side of a house, or other solid object, pupation direction may be a life-death instinct. If they attach on or to a flat object, that side will be darker. If the back of the abdomen is flattened by a stem or wall, the adult butterfly will look and function normal. If the leg/antennae/proboscis area is flattened, it often leads to failure to pupate properly which can cause death or disfigurement that leads to death.

If it is an advantage, those that had an instinct to pupate with their backs to the light would be less apt to survive. The number that die would be minimal, perhaps not enough to make a difference. Was our experience a coincidence or is this the normal ratio of angle to the light that happens all over in the Monarch world?

Fatal damage to the leg side
of a Monarch chrysalis

Please do your own studies. Do they pupate the same way in your house? Do you see more damage with those that pupate with their backs to the light? When we all observe what happens in our own caterpillar rearing environments, we all learn.

Spotting late Monarchs?

Why are people reporting so many Monarch (and other species) of butterflies later in the year than normally reported? There are several simple reasons.

  1. More people are noticing butterflies, especially Monarch butterflies. The internet has increased the number of people who recognize Monarch butterflies. More people (than in the past) are aware of the dates they should normally be absent in an area. They record and share the dates that they spot Monarch butterflies in their area. In the past, when people would see the exact same species on the exact same place and on the exact same date they didn’t report it. It meant nothing to them.
  2. More people are raising caterpillars indoors. This protects them from nature’s enemies, including cold temperatures. Many of the butterflies spotted were raised indoors. If they had been left outdoors, low temperatures would have killed them. There are more late-season butterflies because people save them from the weather.
  3. Artificial lighting (along with artificially raised temperatures) in communities and around houses often give a false sense of the time of year to caterpillars under the lights. This can prevent some from going into diapause and/or migrating.
Monarchs overwintering at Norma Gibbs Butterfly Park in Huntington, CA
Monarchs overwintering at Norma Gibbs Butterfly Park in Huntington, CA

Late season butterflies aren’t a reason to panic. Nature will take care of them. If they are where it will freeze, they will die unless they are a species that survives freezing temperatures, such as Mourning Cloak butterflies.

Mourning Cloak butterfly

Extra reports of late-season butterflies are a sign of good things: that people are noticing them and reporting them. When more people are aware of butterflies and their natural lives/life-cycles/timing, they are less apt to use insecticides in their gardens. They are more apt to plant butterfly host and nectar plants.

“Which of these is a butterfly?”

Monarch Life Cycle

The answer, of course, it ALL of them.

It helps to know which stage is a butterfly. When I do presentations for children or students, I always ask that question.

We have a BUTTERFLY egg (undeveloped butterfly), a BUTTERFLY child (young butterfly – caterpillar), a BUTTERFLY teenager (chrysalis – a maturing butterfly – going through sexual maturity), and an adult BUTTERFLY.

They are all the same organism, same critter, just one that is maturing. The caterpillar is not a different creature. It simply has a different appearance. The chrysalis is not a different creature. It simply has a different appearance.

A few years ago, a woman called our office, asking how she can kill the ‘worms’ eating her passion vine without harming the butterflies. She was unable to grasp the fact that the ‘worms’ (caterpillars) were butterflies in child form. Once people grasp that important fact, they begin to use less pesticides and plant more host plants.

Plants and pesticides – how long to wait?

Enthusiasts often run out of leaves for caterpillars and rush to the nursery to buy more plants. Then comes the BIG question: How long should I test it with one caterpillar before placing more caterpillars/leaves together? You won’t like the answer.

Pre-pupae were unable to pupate properly, due to insecticides.

First, to be 100% sure, until it becomes an adult and flies away without problem. If a caterpillar is exposed just before pupating, some insecticides won’t affect them until they emerge as adults. If some pupae are exposed, it won’t affect them until they emerge as adults. The adults will expand and dry their wings, but when they start to fly around, they go into spasms, usually eventually dying with their wings folded over their legs.

Next, at least into chrysalises. Some insecticides (such as used in some oral flea/tick medications) will affect them only when they begin to pupate. The result is deformed or incomplete chrysalises.

Caterpillar dying from insecticide.

If you don’t have that much time and MUST feed the leaves to your caterpillars, wait three days if at all possible. The certified organic pesticide, Bt (a natural soil-dwelling bacteria), takes three days to do it’s job. Three days after caterpillars eat it, the caterpillars die.

Many insecticides will cause almost immediate vomiting (green fluid that stays green) and sometimes convulsions. This isn’t a pain reaction. It’s a nerve reaction. The insecticide acts on certain nerves, causing the caterpillars to jerk around.

Greenish stains are from spitting. They stay green or yellow.
Black/gray stains are from dried hemolymph. Within five minutes of hemolymph (like blood) being exposed to air, it turns black/dark.

Bottom line – the longer the better, up to the adult emerging and flying away.

Pipevine Swallowtail vs Polydamas Swallowtail?

For folks who live in Florida, Southern Texas, and below Tuscon, Arizona, your pipevine plants may be visited by two different swallowtail butterflies. This can cause a problem because most plants that Pipevine Swallowtail caterpillars can safely eat will kill Polydamas Swallowtail caterpillars and vice versa.

Now it’s a bit easier for you. Click here to visit our page that shows the difference in egg, larva, chrysalis, and adult forms of these two species.

Can you tell which is Pipevine Swallowtail and which is Polydamas Swallowtail?

Southeastern U.S. Butterflies and Their Plants

Butterfly species vary from area to area, state to state, and region to region. Plants chosen for a butterfly garden in Florida many not be the best plants for a garden in New York or Oregon.

For the Southeastern US, these are some of the plants that would be great in a butterfly garden.

  • Pawpaw for Zebra Swallowtail
  • Pipevine for Pipevine Swallowtail
  • Fennel, parsley, dill for Eastern Black Swallowtail
  • Black cherry, tulip poplar for Eastern Tiger Swallowtail
  • Spicebush, red bay, sassafrass, for Spicebush Swallowtail and Palamedes Swallowtail
  • Milkweed for Monarch and Queen
  • False nettle, hackberry, for Eastern Comma, Question Mark, Red Admiral
  • Passion vine for Gulf Fritillary, Zebra Longwing, Variegated Fritillary, Julia
  • Asters for Pearl Crescent
  • Willow, hackberry for Mourning Cloak
  • Willow, black cherry for Red-spotted Purple
  • Willow for Viceroy
  • Hackberry for Tawny Emperor and Hackberry Emperor
  • Hackberry for American Snout
  • Senna for Cloudless Sulphur, Orange-barred Sulphur, and Sleepy Orange

Many of these plants are available online from Shady Oak Butterfly Farm.

Should I or should I not? What do you think?

There is a concern expressed by enthusiasts who want to remove the head capsule from a molting/molted caterpillar. Should you? Or not?

A Monarch caterpillar with its old head capsule over its mouth, molting.

There are two beliefs on this. One belief is that, if it molted and can’t get its head capsule off, an enthusiast should remove it to allow it to eat and grow. The other belief is that, if it didn’t take it off naturally, removing it and allowing it to live and lay mate may pass on a defective gene, one that may have interfered with the molting process.

A Monarch caterpillar in the process of actively molting.

There is a challenge to be sure that it has finished molting. Removing it too soon will kill it. If it has been observed molting and it has been a while with the head capsule still on its mouth, what do you think?

What are your thoughts? Please comment below.