Raising Swallowtail Butterflies

Raising Swallowtail Butterflies

My kids, especially my seven-year-old son, asks me if we can get a pet all the time. The requested animals range from fish, to hamsters (“they poop every 5 minutes!” he says, like it’s a positive attribute), to a new dog (since ours died in April). I don’t want any more pets to take care of, clean up after, or (in the case of small animals that die) dispose of. That is the beauty of raising butterflies: almost no mess, they stay with you only a short time (much of that in their chrysalis), and then they fly away. The perfect temporary pet!

Swallowtail Butterfly in enclosure
Newly emerged, a swallowtail butterfly slowly explores the enclosure as its wings harden.

Of course, there’s more benefit to having a butterfly in the home, including bringing the outside inside, engaging kids in the garden, talking about insect life cycles, reducing any squeamishness around insects, and teaching about respecting creatures by not touching delicate ones. And, who doesn’t love looking at a butterfly up close?

Close up Swallowtail Butterfly wings
Close up of the wings of a Swallowtail Butterfly

Butterflies are also important pollinators in the garden, and aiding them in their delicate transition could make the difference between survival and becoming a snack.

Finding Swallowtails

The Swallowtail Butterfly starts its life on plants in the carrot family called “Umbellifers.” This family includes carrot, dill, and parsley, and indeed the caterpillars are sometimes called “parsley worms.” Another plant in this family is fennel. As you may know, wild fennel is an abundant weed in the Bay Area, and the very worst weed in my yard and garden. Despite my most violent and merciless eradication efforts, I often have to cut down huge trees of the stuff. When I do, I employ the kids to help me search the stalks and fronds for Swallowtail eggs, caterpillars, and chrysalises. Those that we find, we place in a special enclosure with a plate underneath (most enclosures have a soft base), and a container of water to keep some cut fennel alive for the caterpillars to eat.

If you do bring a caterpillar into your home, be aware that you should always cover the water¬†with foil or plastic wrap to ensure a very clumsy caterpillar doesn’t become a very drowned caterpillar.

Caring for Caterpillars

All the caterpillars need is fennel or dill fronds to eat. They should be fresh, so when one stalk wilts, bring in a new one and then remove the old ones when the caterpillar moves to the newer stalks. The caterpillars will eat (and eat and eat), and it is adorable, and then they will poop a lot. Luckily, all they eat is fennel, so it’s pretty dry and boring poop, but it is spherical and will roll off of surfaces.

When the caterpillar is plump and full, it will choose a sturdy place from which to hang his chrysalis. Starting out, this will look like it just glued its feet to a stalk or wall of the enclosure and made itself a thin seat belt to hang from. Slowly, the chrysalis will turn solid green and then a light brown. It is fairly sturdy, but don’t jostle the chrysalis. Keep the enclosure safe, away from direct sunlight, for about two weeks, but be sure you’ll be checking in regularly. Butterflies are fairly quiet, and you don’t want to miss noticing the emerged butterfly.

Releasing the Butterfly

The newly-mobile butterfly will need a few hours to get its wings ready for flight, but once it emerges, plan on releasing it in a few hours. When you see the butterfly attempting to fly, you’ll know it’s ready for the big wide world.

Swallowtail Butterfly just before release outside
Our latest butterfly, just before flying away. You can see the open chrysalis just to its left.

If you need to leave the butterfly in it’s enclosure for a long period of time, such as if you have to go to work, leave some cut citrus fruit or a small container of sugar water (large ones might allow an awkward new butterfly to drown!) in the enclosure. However, you should plan on a release as soon as possible after the wings are ready.

Housing a caterpillar and releasing a butterfly is a wonderfully fulfilling activity for kids and adults alike, so keep an eye out for those adorable caterpillars when you are hacking that fennel!



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