Butterflies in Winter

cecropia moth in the house with hand

Butterflies are sun-lovers, so much so that they can be considered little solar-powered beings who are dependent on the warmth to stay active and fly around.

So how on earth could be a butterfly be flying around in winter? It may seem like a strange concept but it’s not uncommon for our Naturalist to receive multiple calls through fall and winter from people who find themselves with an unexpected winged friend in their living room or basement!

How does this happen? You may remember our previous blog article on swallowtail caterpillars and how they overwinter as a chrysalis. This is a common way for butterflies and moths to “hibernate” until the warmer weather returns.

In this stage, although they are dormant (not moving or eating), they are still very much alive and in tune with their surroundings. Their development is dependent on the ambient temperature: in order to remain dormant until the appropriate season, the butterfly-inside-the-chrysalis must stay cold.

Sometimes the chrysalides are brought into our warm homes, usually inadvertently. House plants that have been put out for the summer had caterpillars living on them, even Christmas trees or other cut foliage, these are some of the vessels that can transport a chrysalis from freezing temps to balmy dwellings.

The warmer temperature signals to the butterfly inside the chrysalis that it needs to speed through its development and emerge, “thinking” that spring must be here because it's so warm! Suddenly a winged, adult butterfly is flapping around inside the house, and there’s still snow on the ground.

There are also some butterflies that overwinter as an adult by simply sleeping in the loose bark or branches of a well-sheltered tree. The Comma or Question Mark are two good examples of this type. It takes even less time for them to “wake up in the warmth” and become active.

What can you do if this happens to you? First, try to identify it as one of these species - see some examples below. You can always email photos to our Naturalist if you're unsure!

 

polyphemus moth and cocoon

eastern black swallowtail public domain pixabay

 

Species that overwinter as pupae: Swallowtail (shown right), Sulphur, Moths (Polyphemus moth above left),

  • If it’s a species that overwinters as a chrysalis, then the butterfly will probably only live a couple weeks (which is typical of an adult butterfly). You can keep it warm, feed it nectar (a sugar:water solution), and have it as an indoor guest for awhile if you wish.
eastern comma butterfly summer form

mourning cloak butterfly

 

 

Species that overwinter as adult: Comma (above left), Question Mark, tortoiseshells, Mourning Cloak (above right)

If it’s a species that overwinters as an adult, you have two options:

  • You can find a sheltered place somewhere in a forest (a fallen log, piece of bark, pile of leaves) and let the butterfly go there. It will go back into dormancy for the rest of the winter and re-awaken in the spring.
  • The butterfly can be gently slipped into an envelope and placed in the fridge or your garage – somewhere it will stay cold – and in the spring, you can release it. This a perfectly normal procedure that many entomologists perform for keeping cold-hardy insects dormant.
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