Overwintering Black and Tiger Swallowtails
Some butterflies, like monarchs, migrate to warmer regions for the winter, while others are left behind to brave the winter weather in various stages of the butterfly life cycle.
This includes the woolly bear (Isabella tiger moth) caterpillar, mourning cloak butterfly, and the swallowtail chrysalis…
5 Steps for Overwintering Swallowtail Chrysalides
1. Find a suitable cage for overwintering
I used to believe that swallowtails needed to pupate on sticks. Turns out, they’re just fine forming their chrysalis in the corners of a pop-up mesh raising cage.
We don’t raise many swallowtails so our overwintering broods are typically less than 5 total…a small pop-up cage is all that is needed. If you overwinter larger broods, check out our big cube butterfly cage.
If you have to remove the chrysalis to put it inside an enclosure try this:
Some have also reported success rehanging chrysalides with contact cement
2. Find a suitable spot to keep the cage overwinter
If you keep a swallowtail chrysalis indoors, expect some butterflies before the holidays…and I don’t mean Easter!
Temperature plays a major role in deciding when your butterflies will emerge. We keep ours in a 3-season porch where temps are only a few degrees warmer than the wintry outdoors.
I keep the cage on the north side of the porch, where it gets less sun. I suspect they could eclose prematurely if placed on the sun-soaked south side.
Many raisers report success overwinter swallowtails in their garage.
If you can’t provide a suitable overwintering space, you can also try overwintering swallowtail chrysalides in your refrigerator
3. Give each swallowtail chrysalis adequate moisture for the winter
Based on my experience with monarchs, I believe it’s most important to hydrate your caterpillars. However, it can take a swallowtail months to emerge from its chrysalis, so…
Once a month (on days where the temps are above freezing) I mist the chrysalides with water. I have no scientific evidence that shows this helps. However, common sense tells me it’s not good to go for months on end in a dry climate without access to moisture they’d naturally receive outdoors.
4. Be Patient
Swallowtails aren’t on a monarch timetable. An overwintering swallowtail chrysalis can take months to eclose (hatch), and I’ve heard reports of butterflies emerging after more than a year in the pupal stage.
I would give them the entire season before discarding, but I would not overwinter them twice.
I have heard that spraying daily in the summer coaxes the butterfly to eclose, but this info is only based on a few first-hand reports. Regardless, water isn’t going to hurt them (with good air circulation) and will keep them from drying out.
All of our overwintering swallowtails in Minnesota have emerged in April and May.
5. Let butterflies dry thoroughly before releasing
I have raised eastern black swallowtails, eastern tiger swallowtails, and giant swallowtails. You can place them outside to safely dry in a mesh cage for 2-3 hours. This way, no predators can attack while they are flightless and defenseless. Then open the cage door, and let them fly free to start a new season of swallowtails.
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