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September 14, 2008



We are in the Niagara Region of Ontario, Canada. We are a homeschool family so when we found one of these caterpillars, we took the opportunity to study it. When i wasn't looking, my daughter "petted" him and most of the hairs came off, but luckily she had no reaction. I noticed, from getting some of the hairs on myself, that the hairs are slightly barbed - it stuck in my finger and became itchy to me...

We built a habitat for him with a piece of tree bark and leaves. The next morning, he was "gone". He had climbed under the piece of bark and built a cocoon - Overnight ! it was amazing.

Our concern was - is he still alive? And after reading your notes, we feel better to know that he will probably remain in the cocoon until March/April.

We have been keeping a journal with photos and observations. This is one long science project !! but we are all excited for the results...


Wow Jessica - you've done a lot of research. We left our guy on our back porch where he/she stayed for 8 months. I wrote about it here:


Thanks for sharing this extra information!


Jessica Bumbolo

I apologize that I am writing this post so long after it originally started... But I figure that what I've experienced, may help others who eventually come across this!

First thing... I will give u a short background:

- About 2 months ago, I was walking thru my front yard (Central NY), & happened to glance down to see that I was about to step onto something bright yellow, & moving as if it had a mission! I glanced at it for a few minutes, because I had never seen anything like it before! I was curious, & wanted to do more research on it, so I placed a container in front of it's path... & it walked right in. I didn't feel comfortable touching it, due to the bright color, the hair, & the longer black hair patches that r meant to resemble "thorns" (those r usually signs that the animal/insect/etc could be poisonous to the touch (the hair), could bite, or could sting... for defensive purposes), so I placed some leaves & twigs in the container, showed my 3 children what "mommy found" briefly, took some pictures, placed a breathable lid on top of the container, & placed him in the shade on my porch, while I went to research what I had actually found. After a lot of reading, I confirmed that it was in fact, an American Dagger Moth Caterpillar... I read on, to find out more information about them:
- There is a lot of controversy on whether or not these caterpillars are in fact dangerous in any way. There have been many claims of people having allergic type reactions to the fur itself (from where their skin came in contact with the fur, all the way to full body symptoms... depending on the person & how their body reacted), like swelling, hives, etc. I also read about dogs & other animals who decided to eat 1 of these little guys, & they were later at the vet w/ symptoms similar to eating something poisonous. Then, there were some claims of people being "bitten" &/or "stung" by this type of caterpillar... But out of everything I read, there was not 1 solid piece of evidence or any type of scientific proof stating that any of these claims were valid. So, as a suggestion... Do not handle these caterpillars (better to be safe than sorry)!
- Not even 24 hours after placing the caterpillar into captivity, he was already working on his cocoon! There have been some comments about people becoming worried if/when the caterpillar they r observing:
1) starts to lose it's yellow hair
What I say now, is strictly based on my observations & experience with the American Dagger Moth Caterpillar that I currently have. When he was getting ready to start his cocoon, he did shed off most, if no all of his yellow & black hairs. They were everywhere in the container, & I too became slightly worried about it! But, then I noticed that he was actually using the hairs together with the silk/web, to construct his cocoon! It definately makes sense for them to do that, especially if their hairs do possess something that can be used as protection. Also, u have to keep in mind that they r only hairy as caterpillars... & not moths. So w/ that said, the hair must be shed from their body at some point, before becoming a moth, right?
2) starts to turn (or becomes) green in color... Instead of the yellow & black
Even though the caterpillars r yellow & black at 1st glance, if u were to place them on their back (so u could see their "legs" & the "belly")... Those r actually green in color! Which means that underneath all that yellow & black hair, is a green body. So, when & if the caterpillar does start to shed it's hairs prior to the cocoon stage, & u happen to see him "naked" so to speak... Then yes, u will be looking at a greenish colored caterpillar. It doesn't me he is starving, sick, diseased, &/or dying... So u don't have to worry about that anymore. It just means that he will soon be moving to the next stage!
3) doesn't eat anything u place in it's habitat
This plays a major factor as to when u find the caterpillar, & how close he is to making his cocoon. If he is still growing & shedding his "old suit" for the brand new 1 underneath, that will provide him more room for a little while... Then yes, he should be eating quite often, as well as quite a bit! This is bc he is still growing, & has to eat in order to get to where he needs to be prior to the cocoon stage. So, just make sure that u r providing him w/ plenty of his favorite leaves! Now, if u r like me... & not find the caterpillar until he is full grown, plump, & obviously ready to start his next stage of life... Then no, if he does eat anything, it might not even be enough for u to notice! If he is at this stage tho... U will want to make sure to provide twigs & sticks (w/ the bark still attached) to him. Not only will this give him options as to where he can construct his cocoon... But u may even see him eating the bark off the twigs/sticks (or notice the bark "disappearing" off of them), bc research shows that eating bark right before making the cocoon, helps their body to make the silk/web needed for the job! So, it's not that he is hungry but doesn't like the food u have provided... It could be just as simple as genetics & how nature works! :)
4) starts a cocoon on the bottom of the habitat, or in the leaves
As long as the location of the cocoon is properly made, sturdy, & safe... Then it really shouldn't matter where they decide to construct it! My caterpillar decided to do a small part of it on the bottom of 3 separate (but bunched together) sticks... & the rest was completed on the bottom of the container (partially on a leaf, & partially on the bare bottom). Due to this, the side of the cocoon that was laying on the bottom of the container, is constructed w/ only a very thin layer of webbing (so thin, that u can actually see somewhat inside the cocoon... But thick enough to do what it's meant to do)! So, if he is comfortable & happy... Then just leave him where he lies, bc if u do attempt to move him, u could do more damage than good unfortunately.
5) seems to have an "extra layer/covering" of a thinner web material outside the actual cocoon itself
I really don't think this much matters... My caterpillar made the same thing, from what it sounds like. & it just kind of looks like he made a thin barrier around where he was going to construct the cocoon, as kind of a safety net while he was still exposed & vulnerable to predators. I've noticed again, that this thin layer surrounding the cocoon, has the yellow hairs scattered throughout it... Again, as tho he was doing it for protection!
6) etc...

- Even though it has been a couple months since the cocoon was made, & the caterpillar is still in there... W/ no sign of emerging yet... I kind of curious as to when that day will come? W/ it now being September, & it's starting to cool down quite a bit (w/ the NY snow season just around the corner), I'm starting to wonder if he will hold out til winter? & if that is the case... I will obviously have to bring him indoors soon, but not sure if there is anything else I would need to do? Guess I still have more research to do! If anyone reading this tho, can answer any of these questions for me... By all means, please do!
Thank u for reading this, & I hope I answered some questions for u! ;)

Sassy Priscilla

Hi Betsy

How nice to hear from you. I did nothing to the caterpillar after it made its cocoon. It wont eat at all. Just dont give up on it in the spring when it seems like it should have emerged. The only other advice I can think of is to make sure the jar is big enough for it to emerge without hurting its wings. Dont worry too much about that, either. We raised monarchs over the summer and I forgot to move one before it eclosed and she was just fine!

Thanks for the advice on what the caterpillar eats. Ive had several questions about these caterpillars since I posted this and I have never been able to successfully answer what it eats for sure.

I hope your little ones love the lesson. It is also a long lesson in patience! LOL. I recommend butterflies in the summer for a quick result. Ive been meaning to blog about our experience and have been a bit behind in blogging.

Take care and let me know when yours emerges if you remember!


Hi I am a little late on this thread but came across your fuzzy yellow caterpillar post when I google our fuzzy little yellow caterpillar. We are doing the same thing you did (hopefully). He has turned into a cocoon. I see that it took 8 months for the moth to emerge. Did you change the food/leaves while he was in a cocoon? I am afraid to move the old leaves incase I bump the cocoon or stick it is attached to... Ours is in a jar with a burlap top outside. Thanks for any advice. This has been and will be a fantastic lesson for my children.
ps. The American Dagger Moth/caterpillar eats hardwood leaves. ie maple, oak, etc. we gave our caterpillar maple and he went to town and the next day he was a cocoon!


Hi I am a little late on this thread but came across your fuzzy yellow caterpillar post when I google our fuzzy little yellow caterpillar. We are doing the same thing you did (hopefully). He has turned into a cocoon. I see that it took 8 months for the moth to emerge. Did you change the food/leaves while he was in a cocoon? I am afraid to move the old leaves incase I bump the cocoon or stick it is attached to... Our's is in a jar with a burlap top outside. Thanks for any advice. This has been and will be a fantastic lesson for my children.
ps. The American Dagger Moth/caterpillar eats hardwood leaves. ie maple, oak, etc. we gave our caterpillar maple and he went to town and the next day he was a cocoon!

Sassy Priscilla

Hi again Tori,

I apologize that I dont know what the Dagger Moth Caterpillar eats. A book I have states it eats leaves from a variety of trees but doesnt specifically state which trees. When we got ours, it was ready to make a cocoon. Ive learned a bit about butterflies and moths since I posted this article and wouldnt recommend bringing in a caterpillar unless you can identify it and what it eats. We raised Monarch butterflies over the summer - the caterpillar host plant for monarchs is milkweed.

Turning green does not sound like a good thing. It sounds like it is starving. I really recommend that if it isnt eating that you turn it loose. Ours made a cocoon within one day and did not lose any fur or turn any colors.

Im sorry I cant help further. We only had one Dagger Moth caterpillar and I think I was just lucky with it ready to make its cocoon right away. I know with butterflies, the less handling, the better. Be sure to wash your hands before touching and after.

Best wishes, Sarah

Tori G

hello i already sent u a note this is tori agen ya how i said that he was turning green well now it looks like he is losing his beautiful fur cout and im wondering if that is an sign if he is turning into an cacoon im just wondering and i also want 2 thank the answers u have gave me before i also want 2 know WHAT kind of leaf for her 2 eat i hope she is okay do u know anything that might be usefull for me to have and u told me 2 put him by an tree am i correct well he is in my contaner that i bout him it is an bug cage and i hope hes safe in there i put lots of grass and leafs and an stike for him 2 do an cacoon on MY TEACHER is now wondering 2 i told him about it and he want 2 know what happends i am going 2 read about this animal and hopfully u can help me thx for everything i hope ill be haring from u agen :)

Tori G

hello im tori and i found my catipilliar in the drive way i did not want him to get ran over so i kept him. i put him in my room i put on the fan 2 give him for air will that help him ? and i do not know what kinda lealf to give him and i just put an hole bunch in there i had him this is probably my 5th day having him and he is still alive but not alot of moving he did not turn into a cacoon yet im wondering y? yesterday i changed his habbitat cuz the grass in there was dieing and this morning i founf him in a hole that he made in the grass and he is turning green can i ask y? idk if its his cacoon but all i know is that hes not even hannging up yet for him to be in one im asking if u can make an cacoon on the ground? another thing is i dont know if hes eating cuz he barlie moves and if hes eating hes eating in one sectoin then the other i see him move place 2 place but when he moves 2 one place he stays there for an while can u please answer my questions and reply i really need 2 know...plz and thx...


Thank you sarah for the information!And i have notice today that he has been less active and curls on the stick my family put in his habitat.if he does his cacoon and it falls can that mess up the process and kill him?(i hope not.)right now he is hanging on the stick and not doing anything.Do you think he is ready to do his cacoon?thanks anyway and god bless you!sincerley,katara!(august 2010)


Hi,I am very sorry to bother you once again but i think my caterpillar is dieing and he hasnt eaten any of the leaves. I by mistake left him outside on our porch to long and he wasnt moving. a When i put the ac on and put him up to it he started to move his head a little.Im very worried about him can you help me please?It would help alot.sincerley,Katara.


Hi, I was wondering if you would know what american dagger moth caterpillars eat because i found one in a park and i put water, ferns, and tree sticks.I also put a big leaf but i dont know what kind it is.My caterpillar spike is not eating any of it.Also how long do you think before he turns into a moth?Thanks and god bless you!Sincerley,Katara.
(August 2010)

Sassy Priscilla

Hi Jesse,

Thanks for the question. It took 8 months, but we got our moth. Here is a picture:




What did ever become of that caterpillar?


My nefhew found one just like yours. We made it a big home with things to eat. It moved alot on the first day on the second it had already cacooned. It didn't go to the top though. It stayed on the bottom of the stick and webbed up there. We didin't know if this was normal. How long does it take before the hatch?


ok, i have some questions for crystal about the caterpillar, so
Q1 did your caterpillar ever eat since you had it?
Q2 how long ago did it eat?
Q3 how long have you had it?
theres some questions
comment them back

Amy Molina

I came across your blog while doing my own fuzzy yellow caterpillar search--we have 3 of them now in cocoons!--and saw that your Aidan has a CaringBridge site, as does my own son, Alex. He's now 7 and has a 2-year-old brother, Max. Alex loves bugs--and Star Wars! I'm hoping that your son is still doing well! Alex is awesome! Here's his site if you're interested!! www.caringbridge.org/page/alexmolina
Thanks for the wonderful blog!!


We just found one like this and brought it home to put in my kids' butterfly tree house thing and I have been trying to look it up ever since. Pretty sure it is an American Dagger Moth (so no butterfly, oh well, not sure I have food for them anyway). He crawled up to the "roof" of it and has stayed there for the last hour barely moving or anything. Is he ok? Should I move him to his food or leave him alone? I put soil, wood chips (found him on woodchips), leaves, weeds, sticks in there and he is just hanging out on top. I saw that they "shed their fur". Could it be that or the cocoon thing or am I going to have to have a talk with my son in a day or so? He is moving, but makes me think of something being in labor. Arches way back, curls up. Maybe he is just too lazy to crawl down the sides to his food, I don't know...lol. Any thoughts? Can't wait to see new pictures of how yours turns out!


what fun! can't wait to see what emerges :)

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