As May Garelick’s children’s book asks in its title, we’ve also wondered, “Where does the butterfly go when it rains?” I’ve read that in the summer they find some large leaf to hide under, hide between some stones, or even just cling to a leaf with its wings closed. Chances are, they don’t have much problem finding cover in the summer, especially in our natural landscape. Winter, though, is a time when conventional landscaping practices create problems for butterflies.
Cover in winter
We make sure butterflies have cover over the winter. Except for a few kinds of butterflies (such as red admirals and, of course, monarchs) that populate our area by migrating from the south, the butterflies we enjoy in the summer have overwintered right here in one of their life stages. How else would they be here the next year?
Some butterflies can be found in places such as under the loose bark of trees, in a woodpile, or beneath a rock. If the temperature reaches 60°F, they’ll re-emerge and continue their pre-winter life in whatever stage they’re in. If they’ve overwintered as an adult butterfly, by spring they’re fairly old for a butterfly, so sometimes they look pretty tattered.
Another thing we watch out for is to check any logs we bring inside to burn in the fireplace (a very rare event for us in any case). There could be overwintering butterflies or pupae under that bark!
The stage (egg, caterpillar, pupa, or adult) in which they overwinter is different for different butterflies. (See resources below for some examples.) Fortunately, many of our general earth-friendly gardening practices have also provided cover for overwintering butterflies — even before we realized we were doing so.
For example, we don’t “clean up” the garden in the fall, raking up all the leaves and putting them in a bag out to the curb as so many people do — truly a dead end for any butterflies (or other insects) overwintering in this leaf litter.
We do pile leaves into barrels we create so they can become leaf humus. These are generally leaves we’ve gathered from what people have put out the curb.
A source or a sink?
Why does this matter? We’ve learned that often butterflies are overwintering in this leaf litter. As Carolyn Summers asks in Designing Gardens with Flora of the American East, “Are are yards becoming a source or a sink for butterflies?” In other words, are we attracting butterflies in the summer so that they’ll lay eggs and become larvae, then scooping up these larvae and sending them to the landfill before they become butterflies? We’re trying to be even more careful with our leaf litter, making sure we don’t pile it up too much.
Unnecessary cover
One thing we didn’t fall for are those cute little “butterfly houses.” Nowhere (aside from catalogs selling these things) have I ever seen any information indicating that these are necessary, helpful, or even used (except for spiders). We’ve put our efforts into leaving some flower stalks, old logs, and the usual garden leavings, which truly are necessary for cover.
Overwintering stage for various species
As an egg
- Banded hairstreak
As a caterpillar
- Clouded sulphur: caterpillar or pupa
- Eastern tailed blue: caterpillar
- Great spangled fritillaries: newly hatched caterpillars
- Viceroys: as a small caterpillar in a “hibernaculum”—a rolled-up leaf attached to a twig
- Admirals: as a small caterpillar in a “hibernaculum”
As a pupa
- Black swallowtails
- Spicebush swallowtail
- American lady
- Clouded sulphur: caterpillar or pupa
- Gray hairstreak
- Spring azure
As an adult butterfly
- Mourning cloak
- Question mark
- Comma
Resources
- Save Our Monarchs: