Saturday, July 19, 2014

Raising Butterflies

Black Swallowtail butterfly laying eggs on fennel.
One of my favorite things about summer is butterflies! The first summer we were in our house, my landscaping priority was to create a butterfly garden. It's pretty simple to do- pick a few species you'd like to attract and provide nectar plants for the adults and host plants for the caterpillars. Most caterpillars can only survive on certain plants. The two species I decided to focus on because I think they are the easiest to attract, are Black Swallowtail and Monarch butterflies.
This post is mainly about black swallowtails because it's too early for peak monarch season, but let me talk briefly about monarch butterflies anyway. Monarch butterflies need our help! Monarch populations have been declining in recent years for many reasons, most notably loss of habitat. Monarch caterpillars depend on milkweeds for survival as they are the only host plant. Milkweed has a bad rap, I grew up with my grandpas telling me not to spread the seeds because it was just a weed. Now we know how important milkweed is for monarchs and other pollinators. If you have a garden, consider adding some milkweed. You'd be helping to support monarchs and their awesome migration (they fly south to Mexico every fall) which is at risk. If you want to learn more about it, check out Monarch Watch, a great educational site that even has information about free milkweed for schools and organizations. 
Click here for a Monarch lesson from a few years back.
Rethink weeds: Butterfly weed is a milkweed with beautiful flowers that will also host monarch caterpillars.
I've already had a bunch of black swallowtails. Host plants for black swallowtail butterflies include fennel, parsley, dill, and carrots. I started with parsley and dill but now that I have fennel, it seems to be the favorite. Some good choices for easy to grow nectar plants are coneflowers, black-eyed susans, sunflowers, cosmos, and zinnias.
Several stages of the Black Swallowtail caterpillar starting with an egg on the left and ending with a chrysalis on the right.
Black swallowtail caterpillars are really fun to watch because they go through so many changes. Black swallowtail caterpillars have 5 instars, or stages they go through when they shed skin they have outgrown and take on a new appearance. I've been trying to get a photo with a caterpillar at each instar and always seem to be missing one. Above is a sample of all the different stages I had a couple days ago. The two in the middle are in the same instar but the one on the right is a day or two older. On the far right is a chrysalis hanging on a twig. Black swallowtail can pupate into a bright green or a brown chrysalis. Some say it depends on their setting, they may turn the color most likely to camouflage them, but I've had both colors in the exact same setting.
Black Swallowtail caterpillar eggs
I started paying attention to my fennel and found my first caterpillar egg this year! Since then I've seen females laying eggs (see first photo) and have found several more to bring inside. I found 9 eggs alone this morning just perched on the edge of the fennel. Whenever I try to get a photo of eggs on the fennel outside, it ends up being too windy, so here is a picture taken in my small enclosure inside.
Black Swallowtail caterpillar stretching to enjoy some fennel.
I've brought a few caterpillars inside each year, but never as many as this year! My oldest son is old enough now, 3 1/2, to really appreciate what's going on. He checks on the caterpillars and talks to them all the time. This is a GREAT early science experience. He's been able to see every stage of the butterfly life cycle and can even tell you about the "chrysalis".
Let me tell you something REALLY cool about black swallowtail caterpillars. See that orange blob in the picture? It's called an osmeterium and the caterpillars push it out when they feel threatened. It also releases a scent. I don't think it smells bad, it's just noticeable. You can also see that the caterpillar above has just shed it's skin from the 4th instar (on the stick behind it) and is in the last stage before pupation.
Close up of Black Swallowtail Butterfly wing.
I've always just rigged something up to keep a couple caterpillars in, but this year I wanted to find something larger so I could raise more caterpillars. My grandpa had an old fish tank in his barn so my kind mother cleaned it up for me and it's currently housing my larger caterpillars, including one getting ready to pupate. It will be nice so that the butterflies have a bit more room to move around if I don't happen to be home to release them as soon as they emerge. Did you know that when a butterfly comes out of his/her chrysalis it has "eclosed"? I just learned that word. :)
After some time has passed (usually around 2 weeks) the chrysalis will turn black and you know that the butterfly will eclose soon. When the butterflies emerge, they hang around for a while, pumping fluid into their wings and letting them dry out. Once the wings are totally dry, it is safe to release the butterfly. I let this one go after my kids went to bed because I was afraid of waiting until morning, not having my larger enclosure yet. If a butterfly starts getting agitated and trying to fly away but it's not a good time- bad weather, etc., you can keep them in the dark and they usually chill out.
A Black Swallowtail butterfly at the top of a twig that also holds a chrysalis 
To finish off this post, I'd like to share my Top 5 Reasons to Raise Caterpillars, followed by a plea.
Top 5 Reasons to Raise Caterpillars
  1. Get your kids excited about science.
  2. Observe a miracle of nature.
  3. Photo Opps!
  4. Support pollinators. (butterfly gardens will also support bees and other pollinators)
  5. "Teaching a child not to step on a caterpillar is as valuable to the child as it is to the caterpillar." -Bradley Miller
And now the plea. If you do find a caterpillar and decide to raise it, PLEASE identify it and make sure that you have the correct host plant. You can't get away with just throwing some random leaves in a jar with it and hoping it will make it. Your kids would be really disappointed to wake up to a dead caterpillar. Don't know what kind of caterpillar you have? Check out this FREE Caterpillar Identification Tool from Discover Life!


  1. So much fun! We used to do this in our house also when my kids were little! They still talk about it and they are 20 and 15! Enjoy! :)

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  3. My son participated in a school program about insects and got to raise butterflies. He loved it! After reading your post, I think we could try this at home. I would love to experience it as well. Thank you!