Monarch caterpillars eat butternut squash...

Butternut squash can be a milkweed substitute / alternative in an emergency!

# jump to feedback / questions / comments below

see also:
raising Monarch caterpillars in Santa Barbara
image gallery of milkweed and Monarch caterpillars & butterflies
tachinid flies are killing my monarch caterpillars!
Monarch caterpillars failed to complete pupating into chrysalis... why?

If you search the internet, you'll find almost everyone says that the ONLY thing Monarch caterpillars can and will eat is milkweed, but based on my own experience, that is not true. Monarch caterpillars can also eat butternut squash (though I'm sure they'd rather eat milkweed if it is available). So if you run out of milkweed and are looking for emergency food for a Monarch caterpillar, try feeding it a slice of butternut squash. Here's my story...

We (myself, my wife, and my son and daughter) live in Santa Barbara, California. We've visited the Goleta Monarch butterfly preserve the past several winters to see the Monarch butterflies. The preserve is a grove of eucalyptus trees near the coast in Goleta where every winter, thousands of Monarch butterflies arrive. They stay a month or two, and then leave and migrate back up into the Sierras for the summer. It's amazing walking through the eucalyptus trees and seeing the big hanging clusters of hundreds of Monarch butterflies huddled together in clumps. When the sun comes out, the air will be full of fluttering butterflies. We've been going to the Goleta preserve for several years, but this year there was a volunteer at the preserve who was explaining the life cycle of the Monarch butterfly, as well as their migratory pattern (fascinating stuff). The volunteer had a Monarch caterpillar and was letting the kids hold it. My son held the caterpillar and then he handed it to me. I haven't held a Monarch caterpillar since I was a kid, and it brought back great memories of finding them on milkweed plants when I was growing up (I grew up in the Sierras, not here in Santa Barbara, and we had wild milkweed plants around our house where we'd find a few Monarch caterpillars during the summer). I decided then that we needed to grow some milkweed so my kids could witness the life cycle of the Monarch butterfly.

I bought a seed packet of "Butterfly weed" (milkweed) at a local nursery and planted several pots. Only one seed ever sprouted, and we ended up with one lonely milkweed plant that we transplanted out front. The little plant was doing pretty good, until one day I looked at it and saw that several of it's leaves were missing. I figured that snails had gotten to it, until I looked closer and discovered two Monarch caterpillars... we had our first caterpillars! We were raising Monarch butterflies! Unfortunately, over the next two or three days, the two ravenous caterpillars ate all the leaves on our single small milkweed plant, and then began eating the stems. I tried giving them other food (various plant leaves from our garden including green bean, cucumber, and tomato leaves), plus various weeds, but the caterpillars wouldn't eat any of the stuff. They seemed to only want milkweed, and everything I read on the internet indicated they only ate milkweed. My kids didn't want the two caterpillars to starve, so I (through a lot of luck) managed to find someone not too far away that had some milkweed plants, and I contacted them and they said we could drop our two Monarch caterpillars off with them. The next day we drove over and handed over our two caterpillars, and thought our brief attempt at raising Monarch butterflies was over...

Two days later, I was looking at the stripped, barren milkweed plant and spied a third Monarch caterpillar on it! I have no idea where this third caterpillar came from, but now we had another hungry caterpillar to worry about. I didn't want to bother the local milkweed source again, nor did I want to drive over there again, so I started looking for Monarch caterpillar milkweed food alternatives again online, and found a reference that said Monarch caterpillars eat pumpkin. We didn't have any pumpkin, but my wife was making butternut squash soup and suggested trying to feed the caterpillar a slice of butternut squash. I put the slice by the barren milkweed plant and surprisingly, the little caterpillar began eating the butternut squash!

We moved the caterpillar into a Tupperware and continued feeding it butternut squash slices (I replaced the squash daily since it would dry out). We chuckled when we noticed the caterpillar poop pellets were orange instead of green. Amazingly, the caterpillar not only survived on the butternut squash, but turned into a chrysalis, and then emerged as a Monarch butterfly (who my son name "Butty" (the Monarch butterfly). Butty even fluttered up to and landed on my son's head before he flew off into the sunset.

Here are the pictures as proof that Monarch caterpillars eat butternut squash:

 

1. (above) I discovered two hungry Monarch caterpillars on my only milkweed plant. They soon decimated the small plant, eating every leaf on the plant and then gnawing on the ends of the stems. I tried feeding the caterpillars various leaves (a green bean leaf, a tomato leaf, and a cucumber leaf) from our garden, but they wouldn't eat any of the different plant leaves. My kids refused to let the two Monarch caterpillars starve to death, so after several hours of emailing and calling around, I found a person not too far away with some milkweed in their yard, and they agreed that we could drop our two caterpillars off and they would "foster them"...

 

2. (above) Two days later, a third Monarch caterpillar showed up on the barren milkweed plant. I didn't want to drive him all the way over to the person with the milkweed, so I began to search some more on the internet for alternatives to milkweed for feeding Monarch caterpillars. I found a reference that someone had fed Monarch caterpillars pumpkin, and it had worked. I didn't have any pumpkin around, but my wife just happened to be making butternut squash soup for dinner, and had some butternut squash left over. I cut a slice and placed it by the plant. To my surprise, the Monarch caterpillar began to eat the butternut squash!

 

3. (above) We moved the Monarch caterpillar to a Tupperware container, and then began to feed him slices of butternut squash. I'd replace the slices daily, as they would dry out. As you can see in the above picture, the caterpillar's poop was orange! My son decide to name our caterpillar "Butty"...

4. (above) Butty the Monarch caterpillar grew to full size eating butternut squash, and then turned into a chrysalis.

5. (above) Butty then successfully emerged from his chrysalis as a new Monarch butterfly.  Seeing him come out was amazing.

6. (above) After a while, Butty the Monarch butterfly successfully flew over to a nearby orange tree.

7. (above) Before leaving, Butty the Monarch butterfly flew over and landed on my son's head, perhaps to give him a kiss and say thank you before he took off. It was the strangest thing, as my son was just standing there watching him, and then Buddy fluttered over and landed on my son's head. We've seen a lot of Monarch butterflies since then, and we're pretty sure several of them have been Butty, or Butty's offspring. Our lone milkweed plant recovered and we've managed to raise other milkweed plants from seed and now have several plants, and have since raised more Monarch caterpillars and butterflies. We haven't fed any caterpillars butternut squash since Butty, since we've had sufficient milkweed available, but now we know that in a milkweed emergency, we can feed Monarch caterpillars butternut squash and they'll be ok.

note: We only raised one caterpillar on butternut squash, but if it worked for him, I think it would work on others. We also started feeding the caterpillar the butternut squash when it was medium sized. I don't know how smaller baby caterpillars would do. I haven't tried it again because we haven't needed to, and I felt a little "Dr. Frankenstein" feeding the caterpillar the butternut squash, so I'll probably only ever do it again in an emergency.

August 2014

Comments / Questions / Feedback:

Comment by Kristn on Wednesday, September 09, 2015
Thank you so much for this tip. I had as many as 23 caterpillars eating on my 20 or so milkweed plants. Over the last two days 10 have moved on to make a chrysalis but the ones left have eaten up all my plants. I went and bought organic butternut squash and though some still ate on the stems some are eating the squash! I am so thankful!

Reply by Steve (Cranial Borborygmus)
Kristn, Thank you for your feedback! I'm glad I was able to help. Feel free to post an update on how your caterpillars do on the butternut squash. As I remember, the squash can dry out, so I kept some in the fridge, and just put out new slices as needed. Good luck!

Comment by Joyce on Friday, September 11, 2015
Thanks for this article! I just found my first 3 monarch caterpillars today and my plant is just a few inches taller than yours, but with flowers and leaves still intact. However, I found more eggs on the leaves, so I was starting to worry that I wouldn't have enough milkweed for them. I'll definitely try out the butternut squash! You're a real life saver! (of monarch butterflies) Thanks!

Reply by Steve (Cranial Borborygmus)
Joyce, Thanks for your comment. Hopefully you'll have enough milkweed. I was feeding the butternut squash to a "bigger" caterpillar so it could finish growing and turn into a chrysalis. I'm not sure how really small ones would do if the milkweed runs out just after the new eggs hatch. And of course, milkweed is always better and is what the caterpillars are supposed to eat, so if you can get more milkweed or plant more milkweed, that would be best. But it also seems, as you get more milkweed you also can get more eggs and caterpillars. Sometimes it's hard to have enough milkweed, no matter how much you have! Good luck and let us know how things work out!

Comment by Ann on Saturday, November 14, 2015
I had to relocate 102 caterpillars this weekend and used butternut for the last day before relocation for the biggest and fattest. Unfortunately, although caterpillars do eat pumpkin, if it is the only food source it does result in genetic abnormalities and so is not really suggested for complete eating. It is fine, though, for caterpillars who are within 3-4 days of becoming a chrysalis - as you have found out. The other plant they will happily and healthily eat is moth vine, but since it is considered a noxious weed in New Zealand, it can be hard to find.

Reply by Steve (Cranial Borborygmus)
Ann, Thanks for your comment and information. It makes sense you can't "raise" Monarch caterpillars the entire time eating butternut squash or pumpkin. I'm only suggesting it in an emergency if the caterpillars eat all the milkweed and you have a few caterpillars left with no food (milkweed) who would start to death if you don't do something. I'm not sure at exactly what size/age the caterpillars can start eating butternut squash and then finish growing enough to pupate into a chrysalis. You could certainly be right that it's only in the last 3-4 days. I'm pretty sure it's not much more than that. If the choice is between a caterpillar going hungry and dying or getting some butternut squash to see if it would work, I would get the squash and try (or my kids would never forgive me)! I don't think anyone is going to try raising caterpillars using butternut or pumpkin, because Monarch butterflies will only lay eggs on milkweed, so you won't get any Monarch eggs and then Monarch caterpillars unless you have some milkweed to begin with, but then it often gets eaten up and runs out before all the caterpillars reach full size. The best answer is always to grow more milkweed, but that's not a very good answer for a sad-faced kid holding a hungry caterpillar when there's no more milkweed around! Again, thank you for your comment and info and I would agree, butternut squash and/or pumpkin is for emergency use only, and is only to "finish" the caterpillars, but isn't right to feed them their whole (short) life.

Comment by Molly on Tuesday, January 05, 2016
Thanks for this tip. We still have several pumpkins and not so much milkweed. When the Instar 5s begin to get closer to chrysalis, I'm breaking the pumpkin open for nom nom.

Reply by Steve (Cranial Borborygmus)
Hi Molly, Sound like a good use for your excess pumpkin! Good luck, and thanks for commenting.

Comment by Selma on Thursday, March 10, 2016
Loved your story. Was the squash cooked or raw? Thank you

Reply by Steve (Cranial Borborygmus)
Hi Selma, The squash was raw, just like it would be in nature. Thanks for your question!

Comment by Leslie Williamson on Sunday, May 08, 2016
Monarch caterpillars in their 5th instar will also eat cucumber if no milkweed available. Honest.

Reply by Steve (Cranial Borborygmus)
Hi Leslie, Thanks for the suggestion. Have you feed Monarch caterpillars cucumber then? I'm tempted to try it and see how it works (you're saying just the bigger 5th instar caterpillars can eat it), but I have plenty of milkweed right now and no caterpillars. Good to know. I'd be curious if others have had success with cucumber. Interesting... Thanks for your comment.

Comment by Alex on Friday, May 20, 2016
My milkweed plant has tiny, bright orange bugs. Are these the larva monarch? I almost brushed them off.... then I realized they maybe Monarch. I've looked all over the web for any kind of pics and can't find out. Help....

Reply by Steve (Cranial Borborygmus)
Hi Alex, I'm guessing your tiny bright orange bugs are milkweed aphids. I have another page on this website that is an image gallery, and I've posted a picture of orange milkweed aphids on it. Check it out, and see if that's what you have. Aphids won't kill your milkweed, but they do feed off it by sucking out the plant juice, and will reduce how well the milkweed grows. You can try to wipe them off and get rid of them, but I've found they multiply so fast they're hard to get rid of. They won't effect the Monarchs, they'll just reduce the vitality of your milkweed.

Comment by Debbie Willians on Saturday, June 11, 2016
Thanks so much for the info. 50+ large cats and fixing to run out of milkweed. Cucumbers really do work!!!

Comment by Elle on Sunday, August 14, 2016
Can you feed the caterpillars oranges, strawberries, grapes, or blueberries?

Reply by Steve (Cranial Borborygmus)
Hi Elle, Monarch caterpillars wouldn't eat the fruit you mention. They really only eat milkweed, which is why the Monarch butterflies find the milkweed to lay their eggs on it. But if you run out of milkweed, at least the older caterpillars will eat butternut squash (and pumpkin I think), and will grow enough to then turn into chrysalises and then butterflies. But I don't know of anything else they will eat. When we ran out of milkweed, we tried all kinds of different leaves and other things from our garden, but the only thing they would eat was the butternut squash. Good luck, and thanks for commenting!

Comment by Sherron on Thursday, August 25, 2016
Thank you!!! I live in Washington, D.C. Monarch butterflies are hanging out in the city! I planted milkweed this spring and only 6 stalks came up. I guess there is still hope for me. Thank you for sharing your story. :)

Comment by Cathy in southern Alabama on Thursday, September 08, 2016
I too, ran out of milkweed plants for the caterpillars. I didn't have butternut squash available, but I had zucchini, and guess what? They are all over it! Eating away! I am glad I saw this post online...Thank you!

Reply by Steve (Cranial Borborygmus)
Hi Cathy, Thanks for sharing this. I didn't know that Monarch caterpillars can and will eat zucchini. That's great to know. I do know that when we've grown zucchini in our garden in the past, it's been extremely prolific, and we end up with more zucchini than we know what to do with. We give lots of zucchini away to neighbors... so much that one neighbor joked that they might have to stop answering the door during "zucchini season". Thanks for commenting and sharing your information!

Comment by Trudy on Thursday, September 08, 2016
How do you tell if the monarch caterpillars is in its 5th instar??? I have lots of caterpillars on my milkweed and I'm afraid they are going to run out of leaves to eat. I have some butternut squash and zucchini but I don't know if the caterpillars are big enough to transfer yet. Also, if I put them in Tupperware. What do I put in for them to pupae on?

Reply by Steve (Cranial Borborygmus)
Hi Trudy, Good questions. I don't know how you tell exactly which instar they are at. I just know each time they molt and shed their skin to get bigger, that is an instar, and they go through five instars before they pupate. One source says the approximate length of the caterpillars at each instar is as follows (if you wanted to try to measure your caterpillars): 1st instar = 2-6mm; 2nd instar = 6-9mm; 3rd instar = 10-14mm; 4th instar = 13-25mm; 5th instar = 25-45mm. If they are pretty big, they should be ok eating the butternut squash. If they are smaller, they might not make it. But if you run out of milkweed, there isn't much else you can do. If you put them in a tupperware, you just need to make sure the container has holes so they get fresh air, but that they can't get out. I put some cloth mesh instead of a lid over the top of my container. They make their silk button and pupate hanging on the mesh, but I've also had them do it on a popsicle stick. I'd guess they can also make a silk button on the underside of a tupperware lid. They can grab onto almost anything. Good luck with your caterpillars.

Comment by Trudy on Monday, September 12, 2016
Hi Steve. Thanks for your advice on my monarch caterpillars. I tried transferring 3 from outside into a container with some butternut squash. They refused to eat overnight, so I put them back on the mostly stripped milkweed plants. This morning I threaded some cucumber chunks on the milkweed limbs, and they and their many friends are liking it!!!! Chomping away. Do you think if I move them from outside back into a container they will continue to eat the cucumber? It's going to be in the 90s today and I'm afraid the cucumber will dry out quickly. Also, it would be much easier to keep an eye on them and see when they need more, and to protect them through pupation.

Reply by Steve (Cranial Borborygmus)
Hi Trudy, I'm not sure what to recommend to you. As for the butternut squash, it was two years ago that I used it to feed caterpillars. I'm not sure if they ate it right away, or after they got "sufficiently hungry". I don't think they'll eat it right away since they'd really rather have milkweed, but I just can't remember how long it takes before they'll eat it. I just know that the caterpillars eventually did eat the butternut squash and did fine. If you had more luck with the cucumber (which I never used but others say works) then I'd stick with it. Also, I talked to a "butterfly expert" and said I was afraid the caterpillars might starve to death if I didn't get them more food within a day, and the "expert" said they can go for several days without food. In any event, you might put some caterpillars in a container with both cucumber and butternut squash and see what happens. Good luck!

Comment by Trudy on Sunday, September 18, 2016
Hi Steve. My caterpillars in my tupperware container ate cucumbers for a few days, but a local nursery got some milkweed in, and so I transferred them over to it. They have been eating happily, and crawling on to the screen cover of the tupperware my husband made for me, to turn into pupae. I now have 13 cocoons hanging straight down from the screen cover, and 1 caterpillar still eating. Ok. When these little guys start to emerge, what do they need in terms of space? Will they be able to cling to the screen (it's a rather fine mesh) or to their empty cocoons to let their wings dry? Should I take the milkweed plants (they are in pots) out of the Tupperware to give them more room, or would they maybe like to stand on or hang from the leaves or stems when they emerge? If they need to hang upside down for a while I'm just not sure what is the best way to accommodate them in my situation. Suggestions?

Reply by Steve (Cranial Borborygmus)
Hi Trudy, Congratulations on getting so many chrysalises! Wow! When the butterflies "hatch", from what we've seen (and it's fun to watch), they will emerge from the chrysalis and then hang on the empty chrysalis while they unfurl and pump up their wings, and then let their wings harden and dry. They might crawl around a bit and might hang from the mesh. They need to have their wings hang down while the wings are hardening. After a while, they'll then flutter around and fly away. So you'll want to make sure they have a way to fly out of the enclosure if they are still in it. Good luck!

Comment by Elaine on Thursday, September 22, 2016
Thank you so much for this, I am trying the pumpkin and butternut. I had 3 milkweed plants out of 10 seedlings to survive. I had 32 caterpillars the other day, today I had 3 leaves left and 19. I have moved them to a container with the pumpkin and butternut. Tomorrow my netting cage arrives and they will be moved there. I will keep you posted on how my guys do. I believe its a better chance than none at all.

Reply by Steve (Cranial Borborygmus)
Hi Elaine. Wow, that's a lot of caterpillars. Hopefully all or most of your caterpillars are fairly big already. I wish you the best. Good luck!

Comment by Elaine on Monday, September 26, 2016
Update, I have 32 caterpillars, I found some more milkweed so I keep giving them the fresh clippings and still butternut because some love it. I am hoping I have some start soon with the cocoons. We shall see what happens, I feel like at least I am trying here.

Comment by Mike on Wednesday, October 19, 2016
Great site and info Steve. One thing you may consider is introducing your readers to the Monarch Larva Monitoring Project for additional information and to advance Monarch research through citizen science. I get many caterpillars and my next venture will be to try and raise them.

Reply by Steve (Cranial Borborygmus)
Hi Mike. Thanks for your comment and for the link to the Monarch Lava Monitoring Project at the University of Minnesota. I just took a quick look, and it looks very interesting. I'll check it out more when I have more time.

Comment by Elaine on Wednesday, November 09, 2016
I successfully released 14 out of my 32. A few I lost to black death, others to heavy OE and deformities.

Reply by Steve (Cranial Borborygmus)
Hi Elaine, Thanks for the update. I wish all your caterpillars had made it, but I glad to hear the 14 caterpillars survived. That's almost half, which is much better than they do in the wild I think. It always hurts to lose any of them, but it's great that 14 are now butterflies.

Comment by Stephanie on Tuesday, November 22, 2016
We have one milkweed plant in our small flower garden that has been covered with monarch caterpillars for the past month or more. The closest tree is about 20 feet away. Are the caterpillars able to crawl that far to pupate?

Reply by Steve (Cranial Borborygmus)
Hi Stephanie, I think your caterpillars can easily crawl that far. We have found chrysalises at least that far away from our milkweed plants. They can also pupate on walls, chairs, bushes, pots, and just about anywhere they can hang. Good luck with your caterpillars.

Comment by anonymous on Saturday, December 10, 2016
So glad to get this information on alternate foods for the monarch caterpillars. There is at least one more plant that we've found they will use as a host plant. Eggs were laid on a Vinelike Milk Weed that has a Milky sap. They Hatch, and eat this Vine. There are Heart-shaped leaves type of vine.

Comment by Jann Wittneben on Thursday, December 15, 2016
I tried the butternut squash and have some of the youngsters (3 and 4 Instar) are eating it too. not all of them but some. The 5th instar are all over it! We're thrilled! We have about 50 cats and of course they've stripped the 75 plus plants we had in the yard, and in containers. So I can't thank you enough for putting this info out there where we could find out about the alternative food source. It's saved several dozen so far. We live south of Houston and it's Dec. 15th and still have new eggs coming on. The warm weather has really created havoc down here. The Monarchs have stayed too long; producing into Winter will leave thousands starving. We'll do what we can for as long as we can. The majority of North bound Monarchs will start arriving mid March. We're propagating as many new plants as we can. Thanks!

Reply by Steve (Cranial Borborygmus)
Hi Jann, Wow! Thanks for letting me know this information helped and about your experience. Very interesting, especially for this time of year! I really appreciate the hard work you're doing for the Monarch butterfly! Good luck and Merry Christmas!

Comment by Kelcey on Tuesday, January 31, 2017
If the caterpillars have striped your milkweed plant bare can you save the plant to re-grow ?

Reply by Steve (Cranial Borborygmus)
Hi Kelcey, Yes, even if the caterpillars have eaten all the leaves and the plant is just stems, after a while, new leaves will sprout and grow. My milkweed plants have been stripped several times. That said, it is tough on the plant, and it's better if it gets a chance to grow and get bigger before it gets hit by hungry caterpillars again, but there's not a lot you can do about that. The best thing you can do is just grow more milkweed, but for your current plant, leave it alone and it should grow new leaves. Good luck!

 

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