Butterflies deserve their status as most people’s favorite insect. They dance across our meadows as if they hear an inner music, fluttering, then pausing on a blossom to unfurl their probosces and delicately sip nectar. They don’t sting or bite and manage a complete metamorphosis from egg to caterpillar to pupa to graceful aerialist in a matter of weeks.

And along the way, they spread a bit of pollen from plant to plant. They aren’t as efficient at it as their cousins in the Lepidoptera genus, the moths, with their furry bodies and feather-like antennae. Or as effective as the myriad native and non-native bees that nuzzle into the hearts of flowers. But they’re definitely the most beautiful. Some are migrators from southern states or even Mexico. Many produce more than one generation every summer, keeping us supplied with aerial color throughout the whole season.

This summer I want to introduce their young, the caterpillars. After all, we can’t have butterflies without them!

The first thing you’ll notice is that they NEVER look like their parents, except perhaps in coloration. In fact, they’re a pretty weird looking bunch! Nature equipped many with horns, bristles, or snake-like eyespots. Others can lay on a leaf disguised as bird droppings! Their appearance seems to have more to do with either camouflage or warding off potential predators. But some are quite elegant – striped or scrolled with color and polka dots that hide them in dappled light or blend in with the colors of their host plant.

My sense is that caterpillars – the larvae of a butterfly or moth – exist for two major reasons: to help produce more adult insects, including butterflies et al., and to feed the rest of nature. So insects lay lots of eggs because the survival of their species depends on a few of their offspring making it through the gauntlet of hungry creatures that would like to eat them. In winter, birds pick frozen eggs, pupae and caterpillars off tree bark or from under leaf litter. Frogs, toads, fish, turtles, salamanders and such gobble up their nymphs or naiads in wetlands. Caterpillars’ soft bodies are full of fat and protein, so adult birds stuff millions of them down the fragile throats of their nestlings as an ideal baby food. So you can see why protection is more important than beauty for butterfly offspring!

So allow me to introduce some of the butterflies I see most in our parks, their zany offspring that feed the nature around us and native host plants that feed the caterpillars.

Mourning Cloak (Nymphalis antiopa)

On cold, but warming March days, it’s heartening to see a Mourning Cloak flying across your yard! This tough customer spent the winter as an adult, hunkered down in a wood pile or under the loose bark of a tree. The previous autumn, it produced a kind of anti-freeze to protect its tissues and went into diapause. When the temperature rose just a bit, it emerged to feed on tree sap, rotten fruit or the nutrients left in carrion and bird droppings! Try not go “Eeewww.” Hey, food is scarce for a March butterfly here in Michigan!

Tree leaves often serve as host plants for early spring butterflies since trees leaf out before flowers bloom. The Morning Cloak uses native birch, willow, aspen, or elm as hosts for its caterpillar.

Red Admiral (Vanessa atalanta)

Red Admirals flashed their orangey-red epaulets all over the township this spring, probably because it was such a mild winter. They can’t easily withstand super cold ones. Some migrate here each spring; some may overwinter if the winter is mild. They too appear when the weather is cooler and usually eat like the Mourning Cloak, but when the weather warms up, they look for nectar on flowers.

The favorite host plants for their caterpillars are nettles, of all things! Native False Nettles (Boehmeria cylindrica) don’t sting because they’re hairless, but I don’t think most of us would seek them out as garden plants. So I have to admire the boldness of my birding friend Ewa Mutzenmore who keeps a patch of Stinging Nettle (Urtica dioica) in her yard just because she loves these little creatures! And they show up each year!

Baltimore Checkerspot (Euphydryas phaeton)

Back in May, I spotted a caterpillar chewing on a plant in the field at Draper Twin Lake Park. Using my handy guidebook, Caterpillars of Eastern North America by David L. Wagner, I was able to identify it as the offspring of a Baltimore Checkerspot, a fave of mine! In late June, Louise Hartung, one of our faithful bird box monitors, told me she saw two adult Checkerspots at Draper Twin Lake Park. I wasn’t lucky enough to see them on my walks there this June, so the photo below is one I took a couple of years ago.

This butterfly’s favorite host plant is a lovely native called Turtlehead (Chelone glabra), though if it’s not available, it will eat some non-natives lawn weeds like English Plantain (Plantago laceolata). How about planting some turtlehead and donating a few stems to a hungry Checkerspot?

Viceroy (Limenitis archippus)

Two Viceroys danced along the path at Draper Twin Lake Park in May. These Monarch look-alikes are usually a bit smaller than their larger counterpart and have an arching band on their hindwings. Entomologists used to call Viceroys “Batesian mimics,” meaning an edible species which developed the coloration of a inedible one for protection from predators. But further research showed that the Viceroy is naturally just as inedible as the Monarch! So they’re now called “Müllerian Mimics.” That’s when two unpalatable species benefit from a similar color and design. If a shared predator tries to eat either one, it avoids that color and pattern thereafter!

Viceroy offspring are one of the caterpillars that use a slightly gross but effective camouflage to escape predation – the bird dropping disguise! Adult Viceroys seek out the leaves of native trees as host plants, particularly willows and cottonwoods. I’d choose the native Pussy Willow (Salix discolor) or Black Willow (Salix nigra) if your landscape has some moist soil. (Click on photos to get full view.)

Black Swallowtail

A male Black Swallowtail (Papilio polyxenes) kept company with my husband and I at Charles Ilsley Park one Sunday morning. The handsome caterpillar of this adaptable creature evolved to feed on members of the carrot family. It finds its native host plant – Golden Alexander (Zizia aurea), a member of the carrot family – in our township’s restored prairies.

The Black Swallow caterpillar feels equally at home in a suburban neighborhood where it finds non-native plants in the carrot family. That’s why it can also be found munching contentedly on a dill plant to the delight or dismay of a suburban homeowner. It’s a fine example of a generalist. It evolved the ability to digest other plants – like dill, fennel, or cumin – that are also in the carrot family (Apiaceae). So plant easy-to-grow Golden Alexander near your herb pot or garden. With luck you’ll save your special dill sauce!

Eastern Tiger Swallowtail (Papilio glaucus)

Every spring in late May, I see my first Eastern Tiger Swallowtail fluttering high above me in the treetops. It’s one of those spring signs that raises my spirits each time. As the weather warms, I can get its photo like I did in the photo below because unlike most butterflies, the Eastern Tiger seldom flutters while feeding. It just calmly settles on a plant, spreads it wings and begins sipping sweetness – a gift to amateur photographers like me!

The Eastern Tiger’s velvety green caterpillar uses its fake eyes (called eyespots) to scare off would-be predators. It turns dark brown right before it pupates to emerge in all its yellow glory. One of its favorite host trees is Black Cherry (Prunus serotina) which is widespread in our area. But it also makes use of Ash and native Tulip Trees.

Spice Bush Swallowtail (Papilio troilus)

I’ve read that Spice Bush Swallowtails almost always frequent rural landscapes. They are often mistaken for female Black Swallowtails and the dark form of the Eastern Tiger Swallowtail female. What I look for is a velvety blush of blue on the lower hind wings rather than the blue stripes or spots of the other swallowtails.

Caterpillars molt in order to grow and each molt is called an “instar.” Like the Viceroy, the Spice Bush Swallowtail’s caterpillar camouflages itself as a bird dropping, but only for the first 3 instars. But by the 5th instar, it looks remarkably different; its transformed into a realistic snake mimic. Its large eye spots even have tiny white flecks in them, making them look as though they’re reflecting light. It folds a leaf around itself with a web and remains there with its head up all day. If a bird investigates the web, it comes across a “snake head” looking right at it! Now that’s tricky! Right before pupating, its color changes from green to yellow or orange. What a production!

The Spicebush Swallowtail lives up to its name by being hosted on shrubs and trees with spicy smelling (and maybe tasting?) leaves. Its favorites around here are, of course, Spicebush itself and the root beer-scented leaves of the Sassafras tree.

Giant Swallowtail (Papilio cresphontes)

The Giant Swallowtail is one of the largest butterflies in North America and we are lucky to be toward the northern edge of its range. The range continues to move north, though, because of climate change. We may see more of it in years to come since its caterpillar relies on warmer winters for the survival of its second generation pupae in late August. Its huge black and gold wings hovering over a native Bee Balm (Monarda fistulosa) sparks a special moment for me each summer. And look at those gorgeous underwings!

A master of disguise, the caterpillar of the Giant Swallowtail starts out on top of the leaves disguised as bird droppings. But after its third instar, it morphs into another amazing simulation that rivals that of the Spicebush Swallowtail! When viewed head-on, it looks very much like a snake with scale-like markings and even a tongue-like forked red gland that emits a nasty odor when the caterpillar is threatened!

The Giant Swallowtail’s offspring loves citrus leaves, which makes this caterpillar the bane of Florida growers. They call it the Orange Dog! But here in Michigan, its host plant is Prickly Ash (Zanthoxylum americanum), a shrub or small tree with thorns that grows along the woodland edge. Luckily it’s present in our parks. When crushed, the seeds release a citrus scent. No wonder it’s the choice of a butterfly far from Florida’s citrus groves!

Great Spangled Fritillary (Speyeria cybele)

Adult Great Spangled Fritillaries love our native prairies. In mid-to-late summer, it’s easy to spot their bright orange and black wings fluttering from blossom to blossom. They are especially fond of our native Bee Balm (Monarda fistulosa) and all kinds of native milkweeds (genus Asclepias). Thistles are a favorite too. In an ordinary summer, the males would have emerged in June and the females would be emerging about now, though I expect the voluminous rain storms and unpredictably odd weather in general may impact their numbers this July.

The female butterfly lays her eggs in the fall on or near violet leaves. The first little instars, though, must survive the winter under leaves or in leaf litter. If they make it, they will need to feed on violets, their host plant and the only one that they can eat. A tough start in life! Fortunately, nature compensated by making fritillaries prolific egg-layers and gave this one a particularly fearsome-looking caterpillar, so some do survive to flutter in the sunshine of the following year.

American Lady (Vanessa virginiensis)

I read somewhere that the American Lady butterfly (formerly American Painted Lady) can be remembered as “the lady with big eyes.” That memory cue helps distinguish the American Lady from the Painted Lady butterfly (Vanessa caduie). They look very similar but one noticeable difference is the size of their hindwing eyespots. The American Lady has two large eyespots on the underside of the hindwings while the Painted Lady has four smaller eyespots.

American Ladies migrate here from warmer areas, but some do manage to survive our increasingly warm winters. So I was curious about their caterpillars. Like the Spicebush Swallowtail, the American Lady caterpillar uses its silk to weave a nest (usually more than one) out of a folded leaf where it can rest when not feeding. What a colorful caterpillar! It chooses great native plants for its host plant, like Pussytoes/ Cat’s Paw (Antennaria howellii), an interesting small native flower that’s great at the garden edge, as well as Pearly Everlasting and Cudweed.

So I Hope You Enjoyed the “Oddballs!”

Caterpillars are just so weird and wonderful. There’s something great about the elegance of butterflies depending on the plant-eating success of the creepy crawlies that emerge from their eggs. They’re squishy and often hilariously ugly and at first it’s easy to think that all they do is ruin leaves in my garden! But what they’re really doing is transferring the sun’s energy stored in plant leaves to a huge percentage of other creatures, including you and I! In their short lives, insects pollinate many of the foods we’ll enjoy this summer like tree fruits, berries, beans, peas, squash, watermelon – almost any plant that flowers. And the baby birds we hear begging from their parents right now are begging for caterpillars and ultimately adult insects, too!

So I’m glad to have met these caterpillars I’ve ignored for so long. You must have noticed that all but one of the caterpillar photos in this blog are ones other people took! I’m just beginning to pay more attention to these characters after decades of appreciating both butterflies and birds! From now on, I’m turning over a new leaf – in fact, a whole lot of new leaves, looking for caterpillars beneath, on top or rolled up inside them! Thanks for sharing my initial exploration into these important little creatures.