07/19/2026
Good advice
Before you reach for anything to eliminate a caterpillar from your garden, take ten seconds to actually look at what you're looking at.
This chart makes the case visually better than any description can. Every one of those caterpillars, some of which look alarming, spiky, large, or just unfamiliar enough to seem like a problem, becomes one of the butterflies or moths shown on the right. The transformation between caterpillar and adult is so complete that without a reference like this, most people would never connect the two.
The monarch caterpillar is the most widely recognized, with its distinctive yellow, black, and white banding on milkweed. But the black swallowtail caterpillar on your dill or parsley, the eastern tiger swallowtail caterpillar on your cherry or tulip poplar, the mourning cloak caterpillar on your willows or elms: these are all future butterflies that gardeners eliminate regularly without realizing what they're removing from their local ecosystem.
The moth caterpillars on this list deserve particular attention because moths are dramatically underappreciated as a group. The luna moth is one of the most breathtakingly beautiful insects in North America, and its large green caterpillar feeding on walnut, sweet gum, or birch is the only way that adult comes to exist. The cecropia moth is the largest moth in North America with a wingspan that can reach six inches, and it's becoming genuinely less common. Finding a cecropia caterpillar in your garden is a legitimate ecological event worth protecting.
The tomato hornworm entry at the bottom is worth addressing directly because it's the one most likely to generate a strong removal instinct. The tomato hornworm is a significant pest on tomatoes and peppers, and if you have a large infestation, managing it makes sense. But the adult form is the five-spotted hawkmoth, a nocturnal pollinator of flowers with deep tubular corollas that few other insects can access. And as we've noted before, a hornworm carrying white parasitic wasp cocoons on its back should be left completely alone. Those cocoons are the next generation of parasitic wasps that will manage caterpillar populations throughout your garden far more effectively than anything you could apply.
The red admiral caterpillar, which feeds on nettles, is particularly interesting because it means a patch of stinging nettles in an out-of-the-way corner of your property is not just a nuisance to be eliminated. It's potential red admiral habitat. The red admiral is one of the more widely traveled butterfly species in North America and one of the more visually striking, with its bold orange-red bands on black wings.
The practical approach this chart is advocating is not passive acceptance of all caterpillar damage. It's identification before action. A caterpillar on a plant you care about protecting deserves thirty seconds of identification before any decision is made. If it's a pest species causing genuine damage, address it. If it's a future luna moth or monarch, relocate it to an appropriate host plant or simply leave it to complete its cycle.
Protect your plants. But look closely first. Future wings may be at stake. 🦋
