How Do Butterflies Overwinter?

How Do Butterflies Overwinter?

In cold climates, butterflies aren’t out and about much in winter.
Where are they? How do they show up in spring or summer? Many butterflies pass through a few generations during the warm months, but the “fall brood” doesn’t simply die off. We’ve talked about how monarch butterflies make it through winter by migrating. But migration is rare in butterflies. Here are other ways butterflies overwinter, with examples of species commonly seen in the eastern U.S.

Make a chrysalis!

Tiger Swallowtails (Papilio glaucus)

lay their eggs on a wide range of trees and shrubs, including wild cherry (Prunus spp.) and tulip trees (Liriodendron tulipifera). Caterpillars hatch from the eggs and eat the leaves. When mature, the caterpillar finds an appealing bit of tree bark, leaf litter or a plant stem. There, s/he builds a chrysalis and attaches it with a strong silk thread. The second generation of the year remains in the chrysalis in a dormant state for the winter. You can help ensure these beauties survive by leaving your perennials standing through the winter and by raking some leaves into your flower beds. This also create good insulation and mulch!

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Tiger swallowtail butterfly

how butterflies overwinter, overwinter, overwintering,

Tiger swallowtail chrysalis. Photo by TheAlphaWolf – Own work,

Black (or American) Swallowtails (Papilio polyxenes),

are found in fields, gardens, wetlands and other areas. Their host plants (where they lay their eggs) are herbaceous species including parsley, Queen Anne’s lace, celery and dill (many plants in family Umbelliferae). Like Tiger Swallowtails, Black Swallowtails overwinter as pupa inside a chrysalis. The chrysalis may be brown or green to blend in with the color of its environment. Black Swallowtails attach their chrysalis to plant stems, sticks and rocks, usually within a meter of the ground.

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Black swallowtail. Photo by Greg Hume,

how butterflies overwinter, overwinter, overwintering, butterflies, Black Swallowtail chrysalis, Papilio polyxenes

Black Swallowtail chrysalis. Photo by S. Detwiler,

Crawl into a seedpod…

Eastern Tailed Blue butterflies

(Cupido comyntas) have a different approach. Blues spend the warm months in fields, gardens, streamsides and open woods. They lay their eggs on flowers and leaves of clover and other legumes, which the larvae eat after hatching. Larvae that mature in fall crawl into seedpods to hibernate for the winter. In spring, they pupate and transform into butterflies.

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Eastern Tailed Blue. Photo by Hectonichus – Own work

how butterflies overwinter, overwinter, overwintering, butterflies, Eastern Tailed Blue, Cupido comyntas

Eastern Tailed Blue. Photo by D. Gordon E. Robertson – Own

Curl up in a leaf…

Tawny Emperors (Asterocampa clyton)

stick together for the winter. Larval Tawny Emperors feed only on hackberry leaves (Celtis spp.). In late fall, groups of larvae crawl under a leaf and curl it around themselves to make a shelter. To get the leaf to curl, they wrap a silk thread around it, and the thread shrinks as it dries, pulling the leaf over. Emperor caterpillars often tie the leaf to a stem with silk to prevent their hideout from falling off the tree. In spring, the larvae emerge and go back to eating leaves until they’re mature and transform into butterflies.

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Tawny Emperor. Photo by Greg Hume, wikimedia commons

how butterflies overwinter, overwinter, overwintering, butterflies, Tawny Emperor hibernacula in hackberry leaf

Tawny Emperor hibernacula. Photo by Donald W. Hall, University of Florida

Chill out as an egg…

Some butterflies overwinter as eggs.

A good example is the Banded Hairstreak (Satyrium calanus). This little butterfly feeds on flowers of milkweed, dogwood, sumac, clover and other plants. Females lay their eggs on oak, walnut, hickory, ash and boxelder twigs. The eggs remain dormant through the winter and hatch in spring.

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Banded Hairstreak. Photo by Umbris, Wikimedia Commons

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Red-banded Hairstreak egg. Photo by Jerry F. Butler, University of Florida.

Be a super cool adult!

Amazingly, some butterflies overwinter as adults.

One such species is the Question Mark (Polygonia interrogationis). Question Marks usually have two generations per year. Adults feed on fermenting fruit (drunken butterflies have been seen!), tree sap, dung and carrion. The fall generation seeks out sheltered areas where they spend the winter in a mostly dormant state. In spring, these adults come out of hiding and lay eggs on trees in woodlands and suburbs.

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Question Mark. Photo by and (c)2007 Derek Ramsey (Ram-Man) Wikimedia Commons

Whether they overwinter as a chrysalis, larvae, egg or adult,
physiological changes occur that enable butterflies to survive the cold. The blood becomes enriched/thickened with sugars or alcohols, which lowers the freezing point; water content in the body decreases; and cellular water is bound to proteins to minimize crystallization.

Now that you know
  that butterflies and other pollinators need plants and brush cover year round to complete their life cycles, what can you do to help? Learn about and use mowing strategies that protect habitat!


Lifestyle choices that help butterflies, birds and ecosystems:
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  • Charles Cladel Posted November 1, 2017 6:07 pm

    Great blogs, Anne! I am especially careful about mowing, (especially weed whacking, selfishly, when I whacked over a bees’ nest built at ground level and they chased and bit me most of the way home it seemed). We use the once a year rotational mowing method on our Conservancy-donated 10-acre property, except for public-allowed access pathways (mowed about every 8-10 weeks). Much info here – question about the Tawny Emperor larval stage – many of them in one leaf – do they choose one to weave that support thread to the stem and also, how many in that leaf weave thread to curl that leaf? What an interesting process. Thanks for all your research and information!

    • annealtor Posted November 2, 2017 1:20 pm

      Thanks for your comments on the mowing post and this one! I’m glad you’re enjoying the blog and increasing your sensitivity to pollinators! Emperor larvae are said to overwinter in groups of about 10 caterpillars. I’m not sure how many of them participate in attaching the leaf to the stalk or in curling the leaf. It would be interesting to observe that process!

  • Dawn Krause Posted January 22, 2019 2:31 pm

    Just moved to Lake Michigan side of Wisconsin. Have Never seen so many Monarchs as here. Also, so many different varieties of butterflies. Don’t know why we have had so many instances where Tiger S-tails are fighting with the Eastern Black S-tails but I leave them alone. All this activity in 2018 has given my husband and I so much enthusiasm to fill our yard with as many flowers, shrubs, trees and grasses. Then, too we’ll be helping the bees, bats and birds. Have homes for ALL.

    • annealtor Posted January 24, 2019 4:58 pm

      Thanks for your comment Dawn. It’s so exciting that you have all those butterflies! Interesting about the fights between swallowtails. I wonder if it’s territorial. It’s great to hear you plan to fill your yard with more habitat. The place is lucky you and your husband moved in! There’s such a need for thoughtful, caring stewardship of the land! Thank you for all you’re doing.

  • Gigi vohsen Posted December 1, 2020 2:12 pm

    I am concerned about a chrysalis of a Black Swallowtail that emerged the day after Thanksgiving here in Missouri. I had raised them over summer successfully, but 3 didn’t emerge from their chrysalis. I have overwintered them before and hatched in the following Spring, but never had one hatch in late fall. Should I have let it go when it was able to fly, or continued to keep it in a net house inside and feed it honey and water?
    There are still 2 left and I want to know what to do if they also emerge early?

    • Donalee M Boyd Posted December 10, 2020 9:07 am

      I have the same question in New Jersey. I have 5 black swallowtail chrysalis in my unheated garage. One just emerged as a butterfly and I don’t know what to do. Temps are in the 40’s right now. Any answers?

      • Anne Altor Posted December 10, 2020 1:54 pm

        Dear Gigi and Donalee,
        Thank you for your comments and for your caring work raising swallowtails. It’s possible that unseasonably warm temperatures or genetic issues could be behind your butterflies hatching so late / early. It’s hard to see a creature emerge at a time that isn’t favorable to their survival, but keeping them alive indoors is probably not a great solution for the individual butterfly or the population. As you know, it’s important to overwinter swallowtail chrysalises in an area where they’ll be exposed to outside temperatures and humidity. Hopefully your remaining chrysalises will stay dormant until spring, but with the temperature swings happening under climate change it’s possible that another could emerge if a warm spell occurs. I would probably put these butterflies outside on a plant, as harsh as that may sound, or in a protected area outside where they can experience the rest of their life cycle in nature. Know that you’re doing your best – some parts of this process are beyond our ability to control. Best wishes – let us know how it goes!

        Here’s an article that talks more about overwintering black swallowtail chrysalises:

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