Ask Edith

Questions? Please feel free to email me at with any butterfly, moth, or host/nectar plant question. We will email you personally and copy your questions on this website/blog to provide help for other butterfly enthusiasts.

Question:At what temperature would you say a Monarch egg dies? Or a caterpillar dies?Answer:Some eggs and caterpillars will live as long as they don’t freeze, if it warms back up soon so they can begin developing, eating, and growing. If it stays cold, they’ll die. If it’s above freezing (sometimes even freezing temperatures) a few nights and then warms up nice again, they usually do fine. They are amazing!


We have a milkweed garden with lots of caterpillar. I brought a chrysalis up to my kids’ school in a butterfly habitat net so the children could watch the process. He came out this morning. Can the kids let the butterfly fly out on his own when he’s ready or should I bring him back to the milkweed where he initially formed his chrysalis? Thanks, Edith!!


As long as the day is sunny, temperatures are above 65 degrees, and it isn’t raining, it’s fine to release them. It’s wings should be dry. That takes at least an hour. Congratulations!

Monarch butterfly drinking nectar from butterfly bush flowers


We are raising Monarchs for the second year, and we have 6 cocoons plus 4 more cats getting their white anchors going. We use a butterfly house that seems to work really well (fine mesh on all sides, zippered door, good airflow, diffused sunlight (never direct) and plenty of shade). We vacuum out the frass daily and provide washed fresh milkweed cuttings from our garden (no pesticides) in florist tubes with water. The cats really seem to like it, they eat voraciously and are active, brightly colored, and plump.

There is one cocoon that has a very small brown patch near the top, and suddenly overnight it has developed a long, thin, white filament or thread hanging down from the brown patch. It looks like dental floss.

Is this a disease? Is it contagious? What should we do?

Your thoughts will be much appreciated.


The thread is from a tachinid fly maggot, well known for infecting Monarch chrysalises. Side note: Cocoons are the silk covering around some moth pupae. Monarchs do not make cocoons. 😉

The fly lays eggs on caterpillars, they hatch inward into the caterpillar, and drink its blood/hemolymph until it is in a J or pupates. It then finishes off some of the other innards of the poor thing and drops down by a mucus string. It isn’t a disease.

Somewhere in the bottom of the container will be a brown fly pupa, looking somewhat like a dark brown tictac candy.

chrysalis”>Click here for more information. Question:

I recently brought in Gulf Fritillary caterpillars from the wild about a week ago, and since then 3 cats is dead.  Cats hang dead, hang halfway like your site described, about 1 dead every 1-2 days. What do I do with the other cats in the same container? Should I change the host leaves? There are about 10 cats in my insect container now.


I would euthanize all the caterpillars you have left in the container.  They are most likely infected.  It is normal for all of them to die when some have it.  Some will die as caterpillars and some as chrysalises.

They most likely have NPV.  Be sure to disinfect everything.

Rearing containers, etc, should be soaked in bleach water. They should be soaked between every batch of caterpillars, at least once a month.

Door knobs, light switches, etc, should be wiped down with disinfectant wipes.

If you’d like, you can disinfect leaves before you feed them to kill pathogens on the leaves.

Remember, nature has an arsenal of diseases to kill caterpillars.  When you bring one in, nature may have already infected it.  You can’t un-infect it.  You can only protect them the best you can.

This is a disease (NPV) that Gulfs get often.

I’m sorry, Edith


Question: Lawn Care Service

“We have a lawn care service come out to treat the perimeter of the house, spraying for bugs as they were cheaper than he can do it. So, when the guy came out a few weeks ago, I moved all the caterpillars to a different part of the yard, including all the pots that had milkweed in them. My largest Tropical MW is near the house … and my thought was … will the pesticides that was sprayed around the foundation of the house leach into the plants now making them unsafe for bees, caterpillars and butterflies?”

I learned the hard way when they treated my house perimeter for termites. It took over two months for plants growing within 15’ of the house to be safe again. Rain and irrigation washes the pesticides over the roots of plants. As it washes over roots, the plants absorb those pesticides. I don’t have plants around my house (we will soon have the siding replaced and decided to wait for that) but I was feeding some weeds (cudweed) growing in the lawn to American Lady caterpillars last time it was treated. Green vomit and death told the story of pesticides in cudweed growing even 15′ away from the house.

I’d cut back any milkweed or other host plants. Water regularly if you can. The more it is watered, the quicker the pesticides will clear the area.

I encourage everyone to plant host plants away from the house and to plant them in many different places in the yard. When all host plants are planted together, a praying mantis or wasps have a prepared buffet instead of a slower hunt-and-seek meal. A break of different species of plants between patches of host plants is planting like nature does. It’s a safety issue when it comes to predators being able to easily find their meals.

I’m so sorry, Edith


Why do you send your breeding stock for pathogen detection analysis?

“Why do you keep needing to send your breeding stock to an independent lab for pathogen detection analysis? That implies that even after 10+ years in business you are still not familiar with all the signs and symptoms of all the pathogens and parasites that affect monarch caterpillars.”


“We don’t ‘need’ to send them. We choose to send them so they can screen them at a pathology department at a university because 1) they can detect pathogens long before there are signs or symptoms. Why wait till there are signs and symptoms? It’s like a wellness checkup at a doctors office. It’s responsible butterfly husbandry! 2) We also add new genes to our breeding stock regularly. Before adding new stock, we like to have them passed by a professional pathology department before they are added to our healthy stock. Yes, I am well familiar with Lepidoptera diseases. I have taught and continue to teach the Basic Lepidoptera Disease Course for the Association for Butterflies every year for the last seven years.”

Continued Question:
“Your response appears to be an admission that your farm operation in Florida cannot reliably detect pathogens in caterpillars prior to shipping them to schools.”

Continued Answer:
“Are you misunderstanding the terms pathogen and disease? Screening can detect latent pathogens that are not active diseases. Can you detect the common cold pathogens in your nose? We all have pathogens in our bodies that are not active diseases and most never become active diseases. We want to know what is there BEFORE it becomes a disease. Screening detects pathogens and even non-pathogens. They let us know if there is a change in bacterial flora. Bacteria is essential for life so bacterial flora is always present. We want to know if there are even changes in the flora. You don’t go to a doctor for a wellness checkup if you are sick or showing signs of a sickness. You go because you are NOT and want to just have a general checkup for things that you cannot tell on your own.”


“Is this a Monarch butterfly egg?”

“Are these monarch butterfly eggs? If so what is the best way to keep the milk weed leaves alive after the leaves have been picked off the plant with the egg attached to them?”

“Yes, either Monarch or Queen butterfly eggs. It isn’t necessary to keep the leaves alive. I personally like to place the eggs, with only a tiny bit of the leaf, into a small sealed cup. Remembering that the hatchling caterpillars are TINY, I add a TINY bit of fresh leaf every day to the container after I see them hatch. I make sure the leaf piece is touching the side of the container. They go to the lightest side so I place the leaf on the brightest side of the container. I add a bit of fresh leaf (small bit) every day for a few days. Once they begin to grow, they are transferred to a larger container. If condensation is ever seen on the inside top or walls of my container, it needs more airflow. Containers should never be placed in direct sun or directly in a window, of course! Direct sun in a window can kill them.”


“Do the caterpillars need milkweed STALK?”

“Do the caterpillars need milkweed STALK to develop correctly, because these last set of Monarchs that had problems with their legs only got fed leaves on a stem but nothing thick like the main stalk?”

“No, they will grow and develop properly when fed only leaves. It’s a great question and when we do have problems with caterpillars we raise, we should all think in this way. What could have happened? What was different than last time, when I had no problems?”


“Monarch butterfly can’t hold on with all legs”

“The last 2 Monarchs that I have seem to want to or have difficulty of hanging with 4 legs on a rope to dry or a tree branch and use only two legs at a time. All legs are intact and work.”

“Sometimes they will have physical flaws. Some butterflies will either have deformed or missing tarsi (foot) or tarsal claws (hooked toes). If so, their legs will work but they can’t grasp anything with those legs. Sometimes they fall when they’re trying to pump their wings full and have other issues due to missing tarsi.” (Tarsus = singular. Tarsi = plural)


“What do I do?”

“Attached is a picture…not sure if it’s “alive” or not. I’ve pushed around on it’s body a bit, seems sort of springy, sort of not. 😦 I’ve put it in a glass jar with a wet paper towel at the bottom, twigs and leaves. Wasn’t sure what to do!”

“It is a moth pupa and looks to be in good shape. You can place it in a jar with a bit of shredded paper towel and a little soil. Add a few drops of water to the jar. It may wait untill spring to emerge.”


“Will soap harm Zebra Longwing butterflies?”

“My neighbor showed me the zebra longwings on her passion vine are DEAD. There are about 8 of them. If she used soapy water on the plant before they got there, would eating leaves with the soap (wet . . . or dry) kill adult zebras? It’s the only thing I could think of that might have killed them, but I decided to ASK EDITH.”
“Are you asking about adult butterflies or caterpillars?”
“She came by today and told me all those “dead” butterflies were gone! Apparently flown away. I saw them myself and they looked dead. I touched a couple of them and they seemed dead. They may have been mating, I suppose. They were on passionvine. They were not clustered all close together –
more like single ones and two together. But, I don’t think mating takes two or 3 days. There were no chrysalises, so they weren’t males waiting for a female to emerge. They don’t cluster to sleep 24 hours a day. I’m so happy they weren’t dead . . but I sure don’t understand this mystery.”

“1) She probably saw them roosting or a group of males waiting for a female chrysalis. They hang about when it is cool or dark. It’s how they ‘sleep’. If it is really cool or very cloudy, they will often roost for days. She probably thought they were dead. I don’t know if it was really cool, very cloudy day, or what. If a female chrysalis was nearby, they could have been males waiting for her to emerge. They’ll just sit and wait for her to be ready enough to mate. They don’t wait for the female to emerge. A male Zebra Longwing will mate with a female even before she emerges. Dead butterflies fall to the ground. If they were on the plant, they were alive. I’m glad they were alive!
2) Adult butterflies won’t eat leaves, soapy or not! 🙂 But if soap was all over the flowers, it could harm them. If caterpillars eat soapy leaves, it is not healthy for them. Soap is unhealthy for nearly any animal, human or butterfly. The plant should be well rinsed several times before feeding it to caterpillars.”


“What is the host for Giant Swallowtail butterflies?”

“Hi I found a giant swallowtail caterpillar and I brought it home with me. I would like to know which would be an appropriate host plant so it could survive and I could see it turn into a butterfly.”

“Giant Swallowtail caterpillars are called ‘Orange Dogs’ because they eat citrus trees. They also eat other plants in the citrus family.
They will also eat rue. Normally, they won’t easily change from other plants to rue so if you find one on a citrus tree, it is best to keep feeding it leaves from the same tree.”


“My butterfly hasn’t emerged …”

“My butterfly never came out of its cocoon. It has a tiny hole in the side. When will it come out?”

“Sadly, it will never emerge. The tiny hole is from chalcid wasps emerging from it. While the chrysalis was soft, these tiny wasps laid eggs in the chrysalis. They ate it from the inside out and when they became adults, they ate the hole in the side and emerged from the chrysalis.”