Butterflies in Winter
With snow already on the ground in some areas and the cold winds of winter starting to blow in others,
With snow already on the ground in some areas and the cold winds of winter starting to blow in others, you may be wondering what your beautiful summertime butterfly visitors are up to right now. While most people are familiar with the amazing long migration of monarchs, flying south for the winter isn’t the only option that butterflies have. In fact, many butterflies can and do remain in their northern range, settling in to endure the winter weather in a variety of life stages.
Adults: Butterflies that remain in cold-winter areas as adults find safe places to rest, like cracks in rocks or tree bark, and enter a state known as diapause. This is essentially a kind of hibernation for bugs, where butterflies shut down all their non-essential systems like reproduction and slow their metabolism dramatically. Special chemicals in their bodies work as anti-freeze, and the butterfly remains dormant until warmer weather arrives. These are usually the last butterflies to be seen in an area each fall, and the first to reappear in the spring. Examples include:
- Mourning Cloak (Nymphalis antiopa)
- Comma (Polygonia comma)
Caterpillar: Other species spend the winter as caterpillars, buried deep in leaf litter or soil or rolled into a shelter of leaves. They also enter a state of diapause. In the spring, these caterpillars don’t reemerge until their host plants have begun growing, so many of them use early spring wildflowers or budding tree leaves as hosts. Examples include:
- Great Spangled Fritillary (Speyeria cybele)
- Red-Spotted Purple / White Admiral (Limenitis arthemis)
Chrysalis: Butterflies who spend the winter in chrysalis find a sheltered place like overhangs or deep shrubbery. The chrysalis, like the adult and caterpillar, stops development over the winter months and contains special chemicals to keep from freezing. When the warmer weather returns and the days lengthen, development resumes in the chrysalis and the adult butterfly emerges in time for fresh blooms on nectar plants. Examples include:
- Tiger Swallowtail (Papilio glaucus)
- Spring Azure (Celastrina ladon)
Egg: Perhaps the most vulnerable species are those who spend the winter as eggs, usually laid in late fall in the leaf litter at the base of the host plant. These eggs will hatch in the spring when the host plant has put on new growth. Examples include:
- Coral Hairstreak (Satyrium titus)
- Purplish Copper (Lycaena helloides)
Migrate or Move South: Any butterfly that is unable to withstand freezing temperatures in at least one part of its life cycle must move south for the winter. Some do so in spectacular long migrations, like monarchs (Danaus plexippus), while others simply shift their populations to the southern part of their range, like common buckeyes (Junonia coenia). Other migrants include:
- Painted Lady (Vanessa cardui)
- Variegated Fritillary (Euptoieta claudia)
How Can I Help? You can help butterflies survive their winters, no matter how they do it, with a few simple actions:
- Leave leaf litter beneath trees undisturbed when possible. It’s likely to contain overwintering caterpillars or eggs.
- If you find what looks like a dead chrysalis in your garage or garden shed in the winter, leave it there. The butterfly inside may well emerge when spring comes.
- Offer nectar plants in your garden in early spring and late fall to help the first and last butterflies of the season.
TIP: Want to know how a specific kind of butterfly spends the winter? Visit Butterflies and Moths of North America and do a search. Each species has its wintering information listed under “Life History”. You can also see a list of common butterfly species and their winter habits here.