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Crazy Common Caterpillars

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Crazy Common Caterpillars

My son, Jack, loves books. He is almost one year old and loves to grab them, throw them, chew on them. He also adores books being read aloud to him. The other night I was reading him “The Very Hungry Caterpillar” by Eric Carle and it occurred to me that we often overlook these juvenile versions of butterflies when trying to attract them to the yard. A caterpillar is an eating, pooping machine (much like a baby), and doesn’t have the grace, beauty, or inspiration of an adult catching a breeze or drinking nectar from a flower. But that doesn’t make them less important when planning your landscape.

By now I think everyone knows that Monarch Butterflies need Milkweed plants in order to survive. Like most butterflies, adults will visit a wide variety of nectar sources, like Blazing Star, Coneflower, Black-eyed Susan, Daisies, and Sages, to name a few. Milkweed is a “host plant” meaning, the female Monarch lays her eggs on the underside of the leaves, the caterpillars hatch from the eggs and will eat only the leaves of the Milkweed, growing fatter and fatter until they are finally ready to form a chrysalis, eventually emerging a beautiful butterfly. All butterfly species require a host plant for the caterpillars, though most are not as limited to a specific plant, like the Monarch.

caterpillars danaus plexippus monarch larvae butterfly

Monarch (Danaus plexippus) caterpillar and butterfly

Wisconsin has 13 native Milkweed, AKA Asclepias species, to support this life cycle. Five of these species are either threatened or endangered. This year, we are experiencing a bumper crop of Common Milkweed (Asclepias syriaca) popping up everywhere. If you prefer a shorter Milkweed in the yard, try orange Butterflyweed (Asclepias tuberosa) or white Whorled Milkweed (Asclepias verticillata), both like it hot and dry. For wetter areas, try Red Milkweed (Asclepias incarnata).

caterpillars papilio polyxenes black swallowtail larvae butterfly

Black Swallowtail (Papilio polyxenes) caterpillar and butterfly

The milky white sap in Milkweeds is actually toxic, which is a defense mechanism utilized by the Monarch. The yellow and black markings of the caterpillar are a warning sign to predators not to eat them. Black Swallowtail Butterfly (Papilio polyxenes) have used this tactic to their advantage. Though not identical to the Monarch, the caterpillars of Black Swallowtails have similar green, yellow, and black markings to fool predators. But these caterpillars prefer plants in the carrot family, like Queen Anne’s Lace, Dill, Fennel, Parsley, and of course Carrots. When you are planting the herb garden in spring, pop some extra Parsley plants around the yard (or Dill if you can keep it from reseeding all over the yard). You’ll be rewarded with seeing more of the dark beauties flitting about the yard.

Closely related, and also a common Wisconsin native, is the Eastern Tiger Swallowtail (Papilio glaucus), though with a less attractive-looking caterpillar. The green larvae have two yellowish spots, like eyes, that seem to stare you down if you find them eating the leaves of Cherry (Prunus), Birch (Betula), Ash (Fraxinus), Linden (Tilia), and Tuliptree (Liriodendron).

caterpillars papilio glaucus eastern tiger swallowtail larvae butterfly

Eastern Tiger Swallowtail (Papilio glaucus) caterpillar and butterfly

If you live near an open woodland, forest, or wetland, you are very lucky because you probably see a lot of Red-spotted Purple Butterflies (Basilarchia astyanax). Their host plants are native deciduous trees common in those areas: Willows (Salix), Aspens (Populus), Cherries (Prunus), Hawthorns (Crataegus), Apples (Malus), and Musclewood (Carpinus). So if you are looking for a new tree for the yard, consider something that doubles as a host plant. These caterpillars have also evolved an interesting defense mechanism: they look like bird poop.

caterpillars basilarchia astyanax red spotted purple larvae butterfly

Red-spotted Purple (Basilarchia astyanax) caterpillar and butterfly

Caterpillar photo courtesy of University of Florida

Often mistaken for Monarchs is the Red Admiral Butterfly (Vanessa atalanta). Red Admiral caterpillars prefer plants in the Nettle family (not exactly something you want to encourage in the yard) but have also been known to eat Hops (Humulus). Hops is a fast-growing vine that will quickly grow up a trellis, pergola, or arbor, even in shade. And you can get into home brewing while you’re at it. Maybe we should start a movement: Beer for Butterflies. But with or without the host plants in your yard, Red Admirals seem to show up in large numbers. Probably because there is always someone not pulling their weeds.

caterpillars vanessa atalanta red admiral larvae butterfly

Red Admiral (Vanessa atalanta) caterpillar and butterfly

Even more similar to the Monarch is the Viceroy Butterfly (Basilarchia archippus). Adult Monarchs retain the toxicity of milkweed sap from their juvenile diet. Birds know to leave any butterfly that is black and orange alone. The Viceroy butterfly is especially tricky, because the adults look exactly like a Monarch, but smaller and with a single black line on the hind wings that runs perpendicular to the other black stripes. Viceroy Caterpillars need host plants that are very common in the butterfly world: Willow, Poplars/Aspens, Apples, Cherries, and Plums. In fact, Doug Tallamy, University of Delaware professor and author of “Bringing Nature Home”, says that, along with oaks, these are the best trees for native caterpillars, supporting hundreds of species of butterflies and moths.

caterpillars basilarchia archippus viceroy larvae butterfly

Viceroy (Basilarchia archippus) caterpillar and butterfly

Though all these butterflies and their caterpillars are considered common, I don’t think there is anything common about the feeling I get when I’m toiling away in the yard, sweat burning my eyes, and I look up to see a Monarch taking a rest on my flowers. Or when I’ve had a particularly bad day and see a Swallowtail glide past me as I walk through the nursery parking lot to my car. They look so delicate, yet are tough and resilient. Buffeted by wind and elements, they are just trying to survive in this crazy world. The least I can do is provide a nice home for their kids to grow up in.

For more info: visit www.wisconsinbutterflies.org