Like a good soap opera? Consider opening a “caterpillar hotel.” You can watch romantic love scenes, witness births and deaths, and watch generations grow up and leave home right in your own back yard. It’s better than any hit TV drama!
Swallowtail caterpillars love to munch on fennel.
Photo Credit: Amy Dee Stephens
Right before it spins a chrysalis, the Eastern black swallowtail caterpillar turns very green and measures about 2½ inches long.
Photo Credit: Amy Dee Stephens
The colorful caterpillar turns into this beauty: the Eastern black swallowtail – and they love their zinnias!
Photo Credit: Amy Dee Stephens
What’s a caterpillar hotel? In butterfly lingo, it’s a “host plant,” or the plant on which a butterfly specifically chooses to lay its eggs. When the baby caterpillar emerges, it’s already living on the very plant it needs to eat.
Yes, I realize that some gardeners despise caterpillars that eat up their plants. But we of the butterfly-gardening school actually court these colorful insects and welcome them to our yards.
Of course, offering the right kind of plant brings in the best clientele. If you have a favorite butterfly species, you need to find out what type of host plant it prefers if you’re going to welcome it into your garden properly. (And if you don’t want to hang the welcome sign out for specific caterpillars – like cabbage whites that would eat up all your cabbage – don’t plant their favorite host plant!)
One of my favorite host plants is fennel. It’s simple to grow, easy to maintain and attracts crowds of swallowtail butterflies. On any given summer day, you can expect to see four to 10 caterpillars hatching and feeding on a single fennel plant. And by the time one caterpillar has eaten its fill and is ready to go off and spin a chrysalis (a process that takes seven to 14 days), another baby has hatched and started munching away.
Fennel is a plant that was made to be devoured. And boy, can caterpillars eat! (If human babies grew as fast as these guys, we’d be as big as a bus in two weeks.) Luckily, fennel grows quickly and flowers often, so it rarely gets eaten to the ground.
If you want to bring in the swallowtails like I do, be sure to plant fennel in the right spot. It needs full sun, although it’ll tolerate some afternoon shade. And because it grows to about 3 feet tall and looks somewhat weedy, you may want to plant it toward the back of your flower bed or garden. Call me a rebel, though, because I revel in leggy-looking plants. (That’s what butterflies like!) So my fennel is planted right in front by my mailbox. The mailbox helps stabilize it (most fennel perform best if staked), plus my mail carrier gets to enjoy a heady whiff of the plant’s strong licorice fragrance when she stops by.
The really cool thing about the fennel caterpillar hotel is that it attracts more than just butterflies. I’ve seen the most colorful flies, wasps and other unidentified pollinators hanging around it. But don’t worry – they aren’t scary. In fact, these winged tourists are so captivated by the allure of fennel’s scent and color that you can stand nearby without even being noticed.
So if you’re looking for some homegrown entertainment for the kids, or if you’re seeking a plant that’s fluttering with personality, try your hand at cultivating a host plant, or caterpillar hotel. After all, hosting graceful, colorful butterflies in your garden can be just as satisfying as growing beautiful flowers.
