Add Butterfly Host Plants to Support Caterpillars

May and June have been for working in the garden, not writing about it. At least until now. Quite frankly, I’m exhausted and despite feeling overwhelmed at times with all the plants that need homes and the general maintenance (weeding, watering and plain ‘ole fussing), there’s been one thing that’s slowed me down. Caterpillars. My daughter and I planted fernleaf dill and cucumbers from seed in May. Since toddlerhood, cucumbers have been my youngest daughter’s favorite veg and so it’s been her job to plant it every year. Only this year we added fernleaf dill nearby with the hope that the black swallowtail butterfly will find it. With this in mind, we planted enough for us and enough for them.

It’s been a sort of plant it and forget it thing. With so many other things to tend to like the catmint that’s already splitting, the dahlias that need staking and the bindweed that never stops choking out the roses and climbing the alliums, I pass the veggie garden constantly but lately never pause long enough to really see what’s happening. Until I stopped to take a closer look at the black spots on the dill. It was a Field of Dreams moment. And it feels so rewarding to plant something with the hope that your intended guest will arrive. The mystery of it is how they find it, these delicate little dill plants that hold so much promise. If you plant it, they will come. And they have! I feel honored, I really do.

Second or third instar of swallowtail caterpillar growth — Black swallowtails experience five instars, or growing phases between molts, before leaving the host plant to form a chrysalis where it will metamorphosize. This swallowtail caterpillar with its white saddle stripe and spiky protrusions is probably in its second instar.

Every morning since discovering our swallowtail caterpillars, I’ve first headed out to the veg garden with the hope that these six little caterpillars have survived the birds to see a new day. So far so good and as I write this, only two remain, having reached their final instar before venturing away from the dill to become something even more beautiful somewhere in the garden. It’s a theme that resonates lately, as my oldest daughter prepares to leave for college in August. And while the swallowtail takes just 10-30 days to leave the relative safety of the dill in my veg garden compared to the almost 19 years it’s been since my daughter blessed my life, I’d give anything to slow time just a little. It’s all gone far too fast for a mom whose kids still seem to genuinely LIKE her.

Caterpillars Need Host Plants

Nectar plants like zinnia, salvia and Joe-Pye weed are a dime a dozen in my garden so the butterflies are happy. But I also want host plants to encourage the adult butterflies to lay their eggs in the garden and to do this, I need to know what host plants specific butterflies require. Unfortunately, there’s no one-size-fits all. They have very discerning palates. For example, Monarchs will only lay eggs on milkweed. I got lucky, having made very little effort to bring them here.

Either birds pooped out common milkweed seed or it came in on the wind and found a permanent home here. Whatever the case, I have plenty of adults floating around looking for the right spot to deposit their progeny and a steady show of Monarch caterpillars all summer. The dilemma is whether or not to pull it once it pops up. Common milkweed spreads like wildfire by deep underground rhizomes. When you have a small garden, it’s a problem.

Here’s a list of butterfly species commonly found in the Midwest and their corresponding caterpillar host plants. Unlike those odd family members we all must suffer through at family gatherings, these guests will be worth inviting time and again to the garden table.