Give a caterpillar a chance. Far from being “pests” and “menaces,” these baby butterflies and moths are essential to a backyard ecosystem.
We’re taught from an early age to think of blemishes and natural signs of growing older as flaws in need of removal or destruction. A still tasty but slightly bruised apple rarely makes it to market, and when it does, few shoppers buy it. A birthmark that could have been a thing of beauty is surgically removed. Wrinkles that were years in the making are lasered and collagened away.
It’s the same way with plants. At the first sign of “damage,” we’re expected to impose our will over the natural order of things. A leaf with holes or raggedy edges is a  weakness, and, according to the Landscaping Industrial Complex,  will surely lead to our entire garden’s undoing if we let it.
Caterpillars are especially victimized by this warped pursuit of false perfection. Often labeled “pests” and “menaces,” these essential denizens of healthy backyard ecosystems are treated like foreign invaders in their own land. They’re sprayed, picked off, hosed down and otherwise attacked for the crime of daring to feed themselves. A popular product, BT, is organic but nonetheless lethal; marketed as safe and natural, this bacteria-based treatment is anything but for caterpillars, whose guts rupture after eating it.
Just as often as we malign these animals, though, we simply don’t think about them at all. And that’s a problem, too. Most insects, including many caterpillars, are specialists, meaning they need certain native plants to survive. But many of the plants traditionally used in butterfly gardens are nonnative and do nothing at all for butterfly babies. As I explained in a recent column in All Animals magazine, the confusion runs deep and isn’t helped by poor nomenclature; gardeners across the country still revere the butterfly bush, despite its inability to support caterpillars. To make matters worse, the species, originally from Asia, is now a known invasive, taking over wildlife habitat in the U.S. and even, ironically, contributing to a demise of butterfly populations in England.
The steep decline of monarch butterflies in recent years has jolted the public into action and put a spotlight on the necessity of milkweed for species survival. But I’ve begun to wonder whether enough attention is being given to the impacts of our war with nature on all the other butterfly and moth species struggling to survive in ever-shrinking habitats. Just last year, three species of skipper butterflies in Florida were declared likely extinct, and many more around the country are in peril.
How profound will continued losses be? As entomologist and professor Doug Tallamy has pointed out in his book Bringing Nature Home, 96 percent of North American terrestrial bird species depend on insects to feed their young. To put in perspective the number of insects that requires, Tallamy notes that it takes an average of 9,100 caterpillars to raise one brood of chickadees.
It’s abundantly clear that nature needs our help now more than ever—and that’s true not just for iconic species but for all the living creatures on our planet. Here are five ways to support habitat for caterpillars—and, by extension, many other animals in your backyard:
1. Host the Host Plants: Plants in every layer of the garden support caterpillars, from tiny native violets to towering oak trees. Online resources, including these habitat restoration guides from the Xerces Society, can help you get started.
2. Leaf Well Enough Alone: When we treat our outdoor spaces like living room carpets—leaf-blowing and mowing and fertilizing—we are issuing a death sentence to so many creatures who live among the leafy, grassy layers. By letting organic matter decay under trees and in your garden’s in-between spaces, you can provide shelter for overwintering chrysalises as well as eggs, caterpillars and pupae of many butterflies.
3. Share the Wealth: If you enjoy growing vegetables and herbs as I sometimes do, your local lepidoptera will likely enjoy it, too. Don’t be surprised to find a black swallowtail caterpillar on your dill or a hornworm on your tomatoes. Though many people react in horror to the presence of hornworms, they are welcome in a balanced garden, where parasitic wasps often control the population by laying their eggs in the worms. And those hornworms who manage to escape that fate grow into stunning moths that help pollinate the garden.
4. Learn Your Species: Like any proper host, you can help your guests have a pleasant stay if you learn just a little bit about their needs. That starts with understanding who they are and what they look like at all stages of their short lives. Of the many sites I’ve turned to, the Butterflies and Moths of North America is one of the most comprehensive.
5. Give a Little Respect: Take care to avoid all chemicals, including organic ones that may be healthier for you but deadly to our garden friends. Always be on the lookout for what lies beneath (a monarch caterpillar meandering over to a tree to form a chrysalis) or who’s hiding above (a swallowtail caterpillar curling up in a sassafras leaf). Spread the word about these animals, who are not “creepy,” as a recent well-meaning but poorly worded Washington Post story labeled them, but beautiful in their own right, quietly making their way through the world without much notice. But notice we must. And even more than that, we must take action—before they have nowhere left to go and all the butterflies, and their babies, have disappeared.
A very nice article with great pictures. It reminded me of a book called The Very Hungry Caterpillar. I was thrilled to see many holes in the lower part of my Arrowwood Viburnum this summer. Hopefully eaten by caterpillars that will become beautiful butterflies. I wondered if others would think of butterflies when they saw holes in their plant leaves.
Thank you, Ellen! I haven’t read that – will put it on my list! My friend Steph, who is also a subscriber to this blog and goes plant-saling with me, said recently that she used to think chewed-up leaves were a sign of something wrong. It made me realize that I did, too, when I first started gardening. So grateful to Doug a Tallamy and others for expanding our perspectives. I hope the arrowwoods come alive with butterfly babies!
This post is a few years old so not sure anyone will ever see it. I have attended a lecture by Doug Tallamy and it was amazing. I do however have a butterfly bush at my house that we’ve had for years. This year I noticed 2 Virginian tiger moth caterpillars eating the leaves, so perhaps because while butterfly bush is not native some of the other members of the plants are. I found it remarkable that some of these species are adapting quite quickly to so many non natives being in their habitats.
Hi Nick! Yes, Doug is amazing! That’s really interesting about your BB and tiger moth caterpillars. I would wonder if they truly got the sustenance they needed, though? I’m thinking in particular about animals like the West Virginia white butterfly, who lays her eggs on invasive garlic mustard, mistaking it for her host plant (which is in the same family). The caterpillars who hatch can’t survive on the leaves. On the other hand, some species eat a wide range of leaves, so perhaps you saw one of these more generalist situations? I’m not sure. But if that were the case, it wouldn’t be so much a case of quick adaptation as it is an inherent ability to be a more generalist forager. Interesting, though! I will have to read more about the Va tiger moth! Thanks for writing!
I purchased x 30 hornworms as a natural control for the Virginia Creeper that has taken over my house and yard. They are doing a great job!
Hi Candy, where do you live? Va creeper is a great native where I live, and we have moth caterpillars naturally who eat the vines; then birds come and eat the caterpillars (a process I’m watching outside my window right now as a papa cardinal picks caterpillars off the Va creeper and passes them to his fledglings! :))
Hi Nancy, I’m in Sturgis, South Dakota. I agree. Va creeper is an all around fabulous provider for caterpillars, tiny flowers for pollinators, berries in the Autum and Winter and heavy protection for nests and shelter all year.
I have always loved flowers and butterflies, so when we bought our house 8 years ago, I went to town buying plants that attract them. Soon after I learned about milkweed and planted some of that for the monarchs. It wasn’t until 3 years ago when I saw a Tiger Swallowtail feeding on my cone flowers, took pictures and a video, and posted it on a butterfly Facebook page that I found out about host plants! While I didn’t have host plants for them, I found out I could easily get host plants for black Swallowtails, and RAN to my favorite nursery where I found two tiny caterpillars on some parsley. I was soooo excited and got the only enclosure I could find right away – a mesh hamper at Target. I continued to research, bought two awesome enclosures, and that year raised about 30. The next year around 90, and last year 120! I had 22 overwinter in my garage and 20 eclosed so far. Don’t know if the other 2 are viable, but we’ll see. I also released one I raised from an egg and one from a chrysalis a friend gave me from her fennel. Right now I have probably 20 in various instars as well as in chrysalis. Sadly I’ve seen very few butterflies of any kind this year. No monarchs, and no painted ladies. I saw my first tiger the other day and just a few EBS. The ones I released? Who knows. Cabbage whites are always around tho. I actually saw two mating the other day! Just today I went to the nursery and picked up a Joe pye weed, liatris, and more cone flowers. I’m encroaching more and more on the grass in my yard and allow the clover to flourish, as well as dandelions, for the bees and whoever else wants it. I have a ton of parsley, fennel, and dill, and look for appropriate native plants wherever I go.
Hi Norma, it sounds like you have a wonderful habitat and efforts to help your wild visitors – I am grateful for all your hard work! The butterflies have trickled in here, but we still don’t have the numbers we usually do … I think they are emerging soon, just very late. I saw sulphurs mating today. 🙂 Have you tried golden alexander (Zizia aurea) for the black swallowtails? It’s a native host plant for them, and it’s perennial and spreads a lot, so you don’t have to replant every year!
Never heard of golden Alexander, but I will look for it next spring and plant it in my garden..thanks!
Thanks for this outstanding post. I’m always torn when I see a plant getting decimated by caterpillars or aphids, or Japanese beetles or, in my case, blister beetles. I’ve always taken the “let nature be nature” approach to gardening, and I have been a lifelong student of insects and nature in general.
Two years ago I couldn’t figure out why my virginia creeper vine was disappearing, especially since it’s such a vigorous, mature vine that grows up a large trellis and onto our front porch wall. By late July last year, it was eaten down to the stems with few leaves remaining of any kind. One night I happened to hear something tussling in the detritus below the vine and noticed a horde of massive Achemon moth caterpillars eating the vine down to its base. I had no idea that a heavy infestation of such voracious porkers could be so destructive. Torn between having a vine that helps shade my porch and walls from afternoon sun and letting “nature be nature,” I have since started pulling the chubby munchers off the vine in mid summer.
It’s an existential crisis for me, really, as I grew up being a bug lover, always recoiling when people step on bugs or otherwise kill them autonomically without thought or out of ignorance or misplaced fear. Regardless of how sickened I am by killing a powerful potential food source, however, I just can’t abide that kind of total decimation, as the sphinx moths are so rapacious and so abundant they were on the verge of killing the vine, something I didn’t think was possible with a super strong and vigorous plant like virginia creeper.
I do have a toad who has learned to join me every night for a quick feeding of sphinx moth caterpillars. He’s getting HUGE, but he can only eat three or four of the adults before he becomes gorged and goes back to his toad abode. Nightly I can pull four dozen fat, three to five inch caterpillars off my plant. It seems like a massive waste of food to just euthanize them, but nothing but that single toad seems to mitigate their population explosion, and he can only eat the ones on the very lowest parts of the vine nearest the ground. So, unlike @Norma S above, I don’t ever see birds near the vines, nor do I see parasitic wasps who lay eggs on the caterpillars to make use of them. They seem to proceed quite unchecked and unabated from predation, save for the aforementioned singular portly toad.
I also kill blister beetles by knocking them into a small plastic tub of soapy water as they like to localize on my clematis and they, too, skeletonize my plants quickly. Blister beetles are actually toxic, especially when eaten, so they have few predators. Their toxins are so powerful that they can sicken cattle or even kill horses if they get baled up in large numbers with alfalfa. I kill Japanese beetles in the same way as they have begun to proliferate on some of my rose bushes. As I understand it, Japanese beetles are non native, so their eradication shouldn’t detract from the overall ecology of my neighborhood.
So this killing spree is new to me as I’ve usually just let my garden be. On the other end of the ethical spectrum, however, I do let any naturally seeding native plants like milkweed alone. I’m considered kind of kooky by my neighbors, but I have cultivated a rather large patch of common milkweed in my front garden bed. To passersby in my HOA hyper conscious suburban community, my garden bed looks “weedy” and “unkempt.” It’s not bedecked with hydrangeas, shasta daises and rose bushes, but rather sports as many xeric, pollinator friendly plants as I can encourage to grow. This bed is considered large by residential standards, as it quite conspicuously follows 60 feet of front sidewalk and is ten to twenty feet deep. I’ve planted other varieties of pollinator and butterfly friendly plants in that bed such as Asclepias Tuberosa, which has few competitors for profusion of early summer blooms. As of yet, no Monarchs have lain eggs; however, I have spotted at least three Monarchs feeding on the milkweed flowers this year.
I also let a roost of bats live above my front portico which must be hollow. I’ve counted as many as 40 bats leave the portico at dusk, and they have returned every one of the four seasons we’ve owned the house. We did find a dead bat on the front porch which tested positive for rabies, so we may have to seal up their roost after they migrate south in the fall. We have faithfully (and almost daily) cleaned up bat droppings all over our front porch for the duration of the time we’ve owned the house.
So I want to be – and am – “nature friendly,” someone who most often “lets nature be.” I like to think I’m above average for an American middle class consumer in my “respect” for nature. But there are definitely times when it seems I need to intervene, to slow “nature” down a bit in her relentlessness, or when things get out of balance. After all, once we decide to build a house or a neighborhood, we’ve altered the natural ecosystem severely, and it is impingent upon us as stewards to keep the systems we disrupted in balance as much as possible.
When I do intervene in the extreme case of an extreme caterpillar infestation, I never use pesticides, and I never use weed killers; I only cull when conditions look dire for a plant or a planting. After all, what good to pollinators are plants that are so ravaged they can’t bloom or sustain themselves? That being said, it’s always a fine line to cross, and I do often wonder when looking into a bucket of dead or dying insects what the right thing to do would have been. Possibly I could turn the mass of caterpillar flesh into fertilizer in some way? I’d love to know what others do in that regard. Grind them up to feed the very plants that house and sustain beneficial insects? Seems the balanced, nature friendly thing to do, right? Please advise,as I’m clearly in moral crisis over killing insect pests, even if only in the extreme instances I’ve described above.
Hi Darren, it sounds like you have a wonderful space for wildlife, and I really appreciate that you are trying to figure out how to do the least harm to animals and plants. As for what I would recommend, find that letting things evolve over the long term is really more helpful to both the wildlife and to me. The Virginia creeper vines do sometimes get nibbled by beetles, but then native clematis will seed in and cover that area instead, for example. And the Va creeper will seed somewhere else and grow more lushly. By keeping in mind that nothing’s ever static — that each year will bring new changes, some of which feel like losses of plants and some of which are gains of new treasures sprouting — then I don’t have that sense of attachment to just a single species or a few species. I love them all in totality, as a community working together, living and dying and resurrecting again.
Also I love to learn about the life cycles of some of these creatures, and it makes me admire them even more. You mentioned blister beetles — we see them in spring, and we often see fire-colored beetles on their backs, presumably gathering cantharidin for defense and pheromone synthesis. It’s a fascinating story and one that has yet to be fully studied. I don’t touch them but love just watching them.
Do you get trouble from your HOA, or is it just sidelong glances? That would make a difference in terms of how you approach the front bed and your neighbors. But the plants you describe there sound great to me!