First Frost Often Means the End for Late Season Caterpillars, and a Next Chapter for the Intriguing Frostweed Wildflower

We’re finally getting our first frost in San Antonio, about three weeks after the typical November 21 first frost date prescribed by gardening buffs, farmer’s almanacs and the National Climate Data Center.

Photo by Myra  B Allison, via Ladybird Johnson Wildflower Center
Frostweed spills its guts on first frost creating a beautiful ice sculpture.   Photo by Myra B Allison, via Ladybird Johnson Wildflower Center
Freezing temps usually mean the end of the season for butterflies.   Just this week we’ve had several emails and posts from butterfly wranglers wondering what to do about caterpillars discovered outside–better to let them brave the elements, or bring them inside?

Brought 22 monarch caterpillars in from the cold. Some are already starting to make chrysalises. Some are still eating, and a few have “J’d” but after a day haven’t progressed. Anyone have any hints or advice? Hoping for the best and preparing.
–Tom Kinsey, San Antonio, via Facebook

I can argue the answer to that question either way, and have taken both routes.   A late stage Queen caterpillar was discovered on a milkweed plant in our courtyard this week.  She remained outside.
Considerations included my busy holiday schedule, a lack of host plant, and the probability that when she formed and later emerged from the chrysalis, the butterfly would face cold temperatures (making it difficult if not impossible to fly), little nectar, and few prospects for a mate.  What kind of life is that?

Frostweed is a magnet for Monarch and other butterflies in the fall, a reliable late season nectar source.  Photo by Monika Maeckle
And yet, our friend Marileen Manos Jones of upstate New York took a different tact in late October.  She convinced Southwest Airlines to fly her and a lone lady Monarch to San Antonio in early November to release the late blooming lep at the San Antonio Botanical Gardens.   No “right” answer exists to the late season caterpillar quandary.  It’s a judgment call.
The first frost of the season poses a separate natural majesty not unrelated to butterflies:  the transformation of the excellent nectar plant, Frostweed, into a beautiful ice sculpture.  I love this plant.   Such an overlooked gem.  Can’t figure out why  this easy-to-grow perennial is not sold in commercial nurseries.
In the fall, Frostweed serves as a prime nectar source for Monarchs and other butterflies.  The sturdy Verbesina virginica, with its odd square-like stalks, sports fleshy green flanges on its stems.   The wildflower produces lush white blossoms from late August through November in semi-shade that provides respite from the late summer sun.   The flowers bloom in big colonies along the rivers and streams of the Texas Hill Country.
Frostweed ice sculpture
Frostweed ice ribbons are always a nice surprise. Photo via Ladybird Johnson Wildflower Center
Along our stretch of the Llano River, Frostweed lines the riverbanks.  This last year took a toll on the flowers, as the water table had receded significantly from the 2011 drought.  Many Frostweeds died as stiff stalks in August.
But in general, this plant is gorgeous, drought toleranat, a generous seed and nectar producer, and the butterflies love it.
As a member of the aster family, Frostweed  can reach six-eight feet in height in a good year. Upon first frost, the stem splits, the sap oozes out and freezes to form fascinating curled ice ribbons and intriguing sculptures. That’s why it’s called Frostweed, or sometimes, Iceweed.
Frostweed Seed
Frostweed produces generous seed and nectar. And it’s easy to grow.   Photo by Monika Maeckle
Only a handful of species commonly exhibit this behaviour, according to Dr. James Carter’s website.   Dr. Carter coined the term, crystallofollia, to describe the phenomenon, from the Latin crystallus, ice, and folium, leaf.   Dr. Carter also points out that “the ice formation far exceeds the amount of moisture from sap locally available in the stem, and must be augmented by water drawn up from the roots.”   Frostweed’s rhizomes help it slurp up moisture in the soil to produce the ice formations.  The robust root system also makes it easy to propagate the plant from its roots as well as from seed.
For a fascinating blow-by-blow of what actually occurs botanically in the forming of these sculptures, see Bob Harms’ Biophysica of Crystallofolia website.   It humbles the most talented artist.

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42 Responses

  1. Linda Rippert
    | Reply

    Hi Monica! I have a quick question to ask…..When our Master Gardener or Master Naturalist groups are offering an outreach event, one of our Master Naturalists insists on having live Monarch cats in her booth, and she lets anyone, even very young children hold them and pet them.

    I maintain that since you have no idea what that person has had on their hands while visiting an event with lots of vendors operating a variety of booths about nature, none of them should be touching the cats at all. I am willing to hold the cats in my hands, and am careful about washing my hands frequently during the event. That allows all the people to come by and look at the cats up close, and I can give them info on the type of butterfly or moth we have and to encourage them to visit bookstores or libraries to learn more about butterflies and their lives and activities. We are delighted when we see these folks at our next outreach event and get to hear what they have learned and how excited they are to have learned on their own!

    Do you or any of the groups you work with have any rules about handling the critters you show off during events. Any comments would be welcome.

  2. flo gilcher
    | Reply

    Last year I released 1 swallowtail and this year 6 I gave 4 caterpillars to my friends for their grandchildren I found all of them on my dill can I put a potted dill in my container right with the dill will they eat dill seed? I live in SE Michigan.

  3. Judith Andrews
    | Reply

    If I wait for my caterpillar to make a chrysalis, can I then keep it in a cool, dark place and get it to wait until spring to emerge?

    • Laureen Armstrong
      | Reply

      The last two years I had a swallowtail caterpillar chrysalis in November. I put the net cage in a corner on my mom’s screened in back porch and they winterized…emerged in May. The article I read said they have a form of antifreeze in them but they must be kept in the outdoor conditions (cold, humid, damp, freezing) or they will dry out and die. This year i have eight chrysilis…praying for the same outcome in the spring.

  4. Pearl Hennessy
    | Reply

    I live in Arroyo Grande California not far from San Luis Obispo. Our climate is coastal with mild temps during winter, 60’s during the day dropping to 50’s at night. This is my first year of spotting cats on my milkweed in October thinking they would be done when I released 25 in late July. Now I am finding a few and have decided to bring them inside. they don’t seem to be very active. I have one that is in it’s cocoon. My question is should I put them outside during the day and bring them in at night or leave them out overnight. Temps are dropping to 50-55 at night. I had a thought to cover them at night but don’t know if that’s a good idea or not.
    The smaller ones I have brought in are not seeming to be eating much and some have died. Am I going in the right direction or should I be doing something else to help them survive? We have a huge Monarch grove not far from where we live and some adults are still flying into our backyard everyday so I guess weather conditions are agreeing with their ability to fly.

  5. karen elliott
    | Reply

    I’ve a swallowtail, black cat and it’s just crysalis,I’m in wi.I thought monarch has can’t overwinter, but bl.swallowtail catterpillers do if late,so is depending g of locations?

    • Laurie
      | Reply

      monarchs do not overwinter in wi. or anywhere up north. but lots of other cats will make their cocoons and overwinter in a garage or some other place cold in the winter if your up north. I have a swallowtail cocoon and a cecropia cocoon right now. I am in MN. In spring they should hatch 🙂

  6. Margaret M O'Connor
    | Reply

    I have a new question. I have decided to bring all monarch caterpillars into my home. Despite my best efforts, I can’t save them from the birds and the lizards. I have acquired two fluorescent full-spectrum grow lights for the milkweed plants, and plan to let the caterpillars feed on the live plants. I’m wondering 1) whether exposure to grow lights for 8 hours per day is bad for the caterpillars (I hope not) and 2) how close to the caterpillars the lights can be safely placed. Thanks!

  7. tammy Felbaum
    | Reply

    Hello, you know Ive raised catterpillars for years. I usually start with eggs clear through to adult. Ive raised butterflies and moths, most noteably the 5 giant silk moths native to Pennsylvania.. Well once I raised black swallowtails and the catterpillars scattered when they were about to form into chrysaliss, I couldnt find then anywhere and since they were late season, I just gave up on them. Then one day in december my cat was chasing something behind my refrigator. It was an adult black swallowtail butterfly. We found 4 more that day flying around in our house and a couple the next day. Unfortunately they didnt survive, but what a Christmas present. Live butterflies in December. Also have you ever heard of a chrysalis tree. If you have several catterpillars the same age. Get a tree branch with alot of twigs and put it in some floral foam then put it in a pot. When you see the catterpillars just start to spin there silk to anchor themselves to a spot quickly take them and hang them upside down on one of the twigs of the branch. Let then finish anchoring themselves to the twig. But if the anchoring is well under way you cant take and put them somewhere else. Well Ive done this before and used monarch catterpillars. What a beautiful sight, the. 6 jewel like chrysalis hanging on a small branch. I also collect butterflies and moths. Love Lepodoptera.

  8. Peg O'Connor
    | Reply

    These are new questions. I impulsively brought 7 monarch caterpillars inside on potted tropical milkweed mid-December 2017, just before our first frost. I left a light on the caterpillars and milkweed plants because the milkweed plants prefer full sun. I occasionally spritzed the milkweed plant near but not on the caterpillars. Four pupated, and I released 3 in early to late February. (I probably should have kept them inside longer, but they flew against the window whenever the sun hit the window, and I’m a poor jailer) Questions: 1) It occurred to me that it might be better for over-wintering monarchs to remain pupas as long as possible. Has anyone developed a cool temperature and low light strategy for this? 2) Does anyone know the life expectancy of monarch butterflies emerging in mid-January and kept indoors? One of mine was obviously gravid when released. Thanks so much!

  9. Georgann Weisgerber
    | Reply

    I recently brought in my potted plants and discovered 4 caterpillars on one that contains some citronella. I am thinking they are black swallowtails and am hoping to get to watch them become butterflies! I’m looking for the best ways to assist them through their development stages!!! Help and guidance on the task is welcome!!!

  10. Richard
    | Reply

    Nice article! I have 6 Swallowtail chrysalis in an aquarium – in doors – it’s now late October and they have been in this stage for 5-6 weeks now. So these may finally finish and come out in mid winter? If so, is there a way to keep them until warmer weather or just let them go and hope for the best.
    Thanks for you answer

  11. Rosalba
    | Reply

    Two days ago I found four black swallowtail catipillars on my parsley plant. I brought the plant into my three season porch. Today, when I got home from work, I found one crawling up the screen, one under the railing, one still on the parsley plan, and unfortunately I cannot find the four one. The two “wanderers” I put in glass jars covered with cling wrap and holes for air, with a twig and a piece of parsley. They have assumed the J position and have stopped moving. I live in Connecticut and the days are still warm. Do I need to add water to the habitat? Should I keep them in full sun? I don’t have any experience in raising butterflies and wanted to protect them from birds in the garden. Any advice would be most appreciated! Thank you!

    • Mary
      | Reply

      Better in some shade. Full sun can dry them out. No water or food needed once they are in their chrysalis. Just wait for the transformation. AND I have found that once they are ready to fly if they weather is not right for them, you can cut an orange and give it a bit of a squeeze, and they will drink the orange juice. (Fresh slice and squeeze at least twice a day.)

  12. Donna Suchier
    | Reply

    I found mine at Walmart in the laundry section. They are blue nylon with zipper opening on the side and on the top.

  13. Phyllis
    | Reply

    some one gave a friend who then gave it to me a screen/net type container in which I put caterpillars until they developed into chrysalis after which the monarch is born. I cannot find one anywhere. It could be folded when not in use. I used it and hung outside but it was a good container to protect them from wasps and spiders. The net became rotted and torn and no longer served its purpose. Where can I find another one?

    • Nancy
      | Reply

      Bass Pro Shop sells them in their gift shop with the children’s things for $20. I think you can get them online at Walmart, too. Can look for them online and have delivered to your house.

      • Amy
        | Reply

        I have used the online option a few times to purchase butterfly habitats. Just be sure to read the size! My most recent purchase was a bust— looked just like the full size version, but was only 6 inches tall—no good for raising caterpillars into butterflies.

        • Stephen W. Cooper
          | Reply

          I bought a large clear plastic container put a hinge on lid. Cut a hole 18″x12″ in top and covered that with screen that was hot glued to it. I raise the cats outside until close to chrysalis then put them in cage and feed them until they hatch as butterflies. I then take them outside and put them on feed flowers and let them do the rest. 25-30 this last summer. still have 6 in chrysalis stage in December.

  14. Jim Beauchamp
    | Reply

    I have 4 milkweed plants, 2 swamp aka incarnata and 2 prairie aka sullivantti, which I planted in early May in central Illinois. The incarnatas are 44″ and 30″ tall and the sullivantii are 30″ and 27″. I also have a tuberosa, which is supposed to be good for nectar (19″ tall). We having good weather with lots of sun interspersed with rain.
    But so far I don’t have any Monarch eggs. How can I get them?

  15. Suzanne newcombe
    | Reply

    I live in South Australia its July in the middle winter and probably 2 month left of winter I have about 12 cats all different sizes on my swan plants what should I do bring them in or leave them , I’m just concerned if I bring them in and they turn into butterflys how long can they survive inside help please Suzanne

    • Ross Gilmore
      | Reply

      Hi Suzanne, I live in Gosford NSW and bought my last caterpillar into our sunroom where it turned into a chrysalis on a reed decoration. Bought it inside to be warmer at night, and it hatched yesterday. I put it out on a flowering shrub for a day, but it never moved…
      Currently feeding the butterfly with watered -down honey in an eyedropper . It sits on a potted flower all day and steps onto my finger to be fed. ( you might have to put a nurses uniform on to feed 12 of them ! good luck.)

  16. Ms. Rene' Amond
    | Reply

    I have about 14 Monarch caterpillars in my sport tent ( 4ftx4ftx6ft- made to hold one lawn chair and zip up to shield from cold and rain) which works perfect as a butterfly habitat. Today, I was blessed to find milkweed plants at Lowes and going to buy 2 more containers tomorrow giving me 12 blooming plants. Is it possible to keep the Monarchs in this habitat all winter and release the Monarch butterfly in the spring. I live in Louisiana and it’s been so wet this winter, I feel the Monarch will have difficulty surviving in the cold wet winter to migrate. I just wonder with the blooming milkweed, can the Monarch stay in my habitat all winter?

  17. Traci
    | Reply

    I live in New Zealand, on my plants I have tiny catapillars, we are expecting a bad storm, should I collect all the babies and keep them inside until the weather clears or can they survive by themselves?

    • Fly Girl
      | Reply

      Yes, they can survive in all stages, except the butterfly stage. Butterflies can’t fly in the cold, rain, or cloudy skies. Butterflies need sun to fly and guide them (natural instincts).
      But all the other stages of Monarch butterflies can survive during a storm. I live in Pensacola, Florida and we had a severe storm with a Tornado and the Monarch eggs, caterpillars, and pupas all survived just fine. They have ways of adhering themselves to leaves and stems in the garden. Its amazing!

  18. Patricia Blevins
    | Reply

    I live in San Jose, California and have been bringing monarch caterpillars into my cage on milkweed plants since September. Right now I have 2 chrysalides that look a healthy green but have not opened in 16 days.
    this has not happened to me before and I am concerned.
    The outside temperature the past 3 nights has been about 37 degrees and the daytime temp is 61. Would the temperature have anything to do with this length of time for metamorphosis?

    • Wendy
      | Reply

      I think so based on my experience one year in LA.. See my post above, but basically they stayed in the chrysalis stage through the winter, and emerged in May when it got hot! Don’t give up on them yet!

  19. Gaye Miller
    | Reply

    I have 11 late Queen caterpillars. They will probably not emerge until close to Thanksgiving. I brought them in. I wanted them to at least have a fighting chance. If they have no chance of making it in the real world, what do you think of an existence inside with children being able to watch the process? That sounds like a better life than freezing or starving to death to me. What do you think? Do the Queens migrate to Mexico as well?

    • Monika Maeckle
      | Reply

      It’s not my call, but “butterfly houses” exist all over the country to highlight the beauty and majesty of butterflies. You will need lots of nectar plants, but can also supplement with sponges soaked in gatorade. Let us know what you do and how it goes! –MM

      • Dolly LaLa
        | Reply

        I live in Los Angeles, California where after years of drought the rains have come. I am thinking of keeping my soon to be butterflies inside. Right now I have 6 caterpillars.. I have plenty of Pentas growing outdoors. Do the butterflies need fresh on the bush flowers or will cut flowers be ok? Also, is only one type flower ok, or do they need a variety?

        • Michelle
          | Reply

          Hi i also live in Los Angeles, I don’t have any nectar plants available right now. do you know of any places near Los angeles that the monarchs are overwintering? I have 3 butterflies now and in a few days i should 4 more.

          • Patricia Blevins

            I live in San Jose and in mid December I drove my last butterfly of this season to Natural Bridges in Santa Cruz and released it. The eucalyptus trees in Natural Bridges had many monarchs even though winter was already happening. I think the weather in LA is more then satisfactory for Monarch survival when compared to No California. Good luck!

  20. Toni Hammett
    | Reply

    I just started raising monarch from eggs i have collected. They hatch and grow well, form their button and go into a J but the first 4 have only formed like a “helmet” of their chrystallis and then they eventually die. Ine took over 12 hours trying to form his chrystallis after forming his helmet.
    Can you give me any suggestions. I am in Beverly Hills Florida which is central and near the gulf coast.

  21. carlene
    | Reply

    I like to looks of this plant. Could I grow it in my garden in Zone 6b NEOk??
    I don’t have a formal garden and I have common milkweed, butterfly weed and Tropical milkweed in my garden already.
    If so where can I get seeds.?
    Thank you for your time.

  22. Sheryl Shehane
    | Reply

    I have 17 chrysalis in my home right now. I have already let 4 Monarchs free during the warm days this past week. I have 17 more waiting to arrive. I am concerned about one that has finally turned black/clear. It’s been 3 days and I still can’t see the wings inside, in fact it’s a little cloudy. Is this chrysalis in trouble?

    • Monika Maeckle
      | Reply

      Might have OE. Best to destroy it. Flush it. I know, it’s hard, but the right thing. You don’t want to release an infected butterfly out into the wild, as it will just spread disease.

      • Christye
        | Reply

        A much better way to euthanize , is to put them in the freezer. They just go to sleep..forever ? I know it’s hard,but sometimes necessary . Hope this helps!

        • Patricia Blevins
          | Reply

          thanks for the response. I knew when a chrysalis turns black it should be discarded. The chyrsalis did turn black on the 16th day, yesterday, and I removed it from the cage. The other is still green. I will wait until it turns black and remove it. I have 8 other newly formed chrysalides and I decided to bring the cage indoors as we are expecting temps of 31degrees a couple of nights this week. I knew about the methods of euthanasia and I don’t have any problem with doing this when its appropriate. My question still remains “do lower temperatures create longer intervals of metamorphosis within the chysalis”? If we even know this. Is there a chance butterflies can survive and still migrate when night time temps are in the mid to high 30’s and 40’s and the daytime temps are in the 60’s? Thanks!

          • Wendy

            Several years ago in Louisiana, I found caterpillars and brought them into our classroom. They formed their chrysalis and then nothing happened for several months, through the winter. I figured they were dead but left them in their containers for the students to study and enjoy. To our surprise, after a hot weekend in May, we found them emerging! We watched this amazing transformation, took pictures, and released them!

  23. Ruth and Jim Elder
    | Reply

    Great articles! Thanks!
    Would we be able to grow frostweed in northern Virginia?

  24. peter shavney
    | Reply

    Sunday Nov 3rd I saw 3 Monarchs and a variety of others in flower beds at the Texas Transportation Museum Garden Railroad on Wetmore Road.

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