Where to see the most beautiful butterflies in Sonoma County

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Nothing marks the start of summer like fields of wildflowers and the dancing swift flight of butterflies.

Right now, it’s butterfly season, and they’re busy throughout Sonoma County, painted in an impossible variety of patterns and colors — admirals, tiger swallowtails, coppers, skippers, hairstreaks, checkerspots and painted ladies. Some of them are local, while others, like the painted ladies, are migrating through, en route to Canada.

Recently, butterfly numbers have begun drastically and inexplicably declining, not only here, but worldwide, as scientists raise the alarm.

That’s all the more reason to appreciate a rural, protected sanctuary where butterflies can thrive. That was the vision of Louise Hallberg, who took her mother’s fondness for the native pipevine swallowtail and created just such a place amid the apple orchards of west county outside Sebastopol. Until Louise’s passing in 2017, she tended and grew 9 rolling acres into a varied mix of special butterfly habitats, flyways and feeding gardens.

The Hallberg Butterfly Gardens are still cared for, and are open for the public to visit and enjoy. The habitats are carefully tended, and older sections are being renewed to keep the butterflies protected, and their flyways open among the trees.

Hallberg is holding their annual open house June 23.

On a tour recently with Meghan Peterman, Hallberg’s curator of living collections, she began by explaining that it’s a bit misleading to just call them butterfly gardens.

At times, they’re mainly caterpillar gardens. Although the colorful adult butterflies catch the eye, they owe their existence to the health and survival of the multi-legged munching machines that come before them. To ensure you have butterflies, you need to provide the right plants for the caterpillar, and give them cover from birds and other predators. Only about 10% of caterpillars will survive to become butterflies, Peterman says. And many of them are extremely selective about what they eat. Some can only digest the leaf of one particular type of plant. monarchs, as most know, need milkweed.

The native pipevine swallowtail — a dark, nearly black butterfly with iridescent flashes of teal blue on its hind wings — only lays eggs on a local plant called Dutchman’s pipe, named for the shape of its flower. There are abundant plantings of the vine at Hallberg. Meghan points out eggs, and the occasional black spiky caterpillar among the foliage.

Hallberg is home to another 40 other species of butterfly and moth as well, thanks to careful planning and plantings.

Butterflies are so familiar, it’s easy to take them for granted.

But despite their apparent fragility, butterflies are surprisingly tough, skillful survivors. They’re capable of feats humans can’t begin to match. And scientists are still discovering how intricately well designed they are for the task.

For example, butterflies are remarkable shape-shifters. In its brief lifetime a butterfly will have four completely separate body plans. Each design is based on a genetic blueprint carried in its cells, which also drives the transformation from one form to the next. All of the information is already safely on board the butterfly egg when it’s laid on a leaf.

Morphing from a caterpillar into a butterfly is, biologically, a crazy stunt. After feeding and building up nutrients, the caterpillar goes into its sealed chrysalis, where nearly all of its tissues dissolve. Inside, clusters of cells called imaginal disks begin to guide the reconstruction of the basic building blocks into entirely new features: creating new legs, antenna and the finely patterned wings of the adult.

Why go to all that trouble? It turns out, shape-shifting is a remarkable survival strategy. Each phase of the butterfly’s life requires unique, specialized features just for that stage. The caterpillar needs camouflage to hide, and mouthparts to munch leaves, while the adult needs keen eyes and colorful wings to find mates.

By allowing the butterfly to transform, nature has given it the ability to exploit completely different habitats and conditions over time.

So why do butterflies have such breathtakingly creative wings? Checks, stripes, rondels, frills; vibrant color shades and gradients; veins, spots, borders and crisp outlines — up close, the variations seem endless. But they’re not random. Each type of butterfly has its own, unique pattern. And in a truly remarkable feat, the butterfly’s incredibly keen eyes are capable of immediately detecting the distinctive patterns of their own kind, among more than 18,000 known species, on the fly.

Researchers have only recently begun to unravel the butterfly’s remarkable ability to navigate thousands of miles as they migrate.

Some, like monarchs, take several generations to fly unerringly north from Mexico to Canada, and then do the return in one season. The painted ladies, who departed Southern California in April, will make their way across 1,000 miles in a matter of weeks, clipping along at speeds of up to 20 miles an hour.

How do they pull it off without maps? Apparently, butterflies are capable of telling directions by tracking the position of the sun in the sky using their eyes while calculating the time of day, and aligning to the Earth’s faint magnetic field. Studies have recently discovered the butterfly’s time-keeping cells are located at the tips of their antenna.

UC Davis professor Art Shapiro, one of Northern California’s foremost butterfly experts, is among the group of scientists who have been recording the steady, alarming decline of butterflies and other insects in recent years. His own field studies and careful butterfly counts have measured changes in monarch and other species in Northern California. “monarchs,” he says, “are just one of many species going downhill; three once-common species have already gone regionally extinct or nearly so, with others threatening to follow suit.”

After 60 million years of gracing Earth’s skies, it’s not certain how many butterflies will be available for viewing by generations to come.

The causes are still being debated, but at the moment, the trend shows no sign of slowing or reversing. Measures to provide protections and habitat are in discussion.

For now, they’re on the wing, and available to enjoy.

Stephen Nett is a Bodega Bay-based certified California naturalist, writer and speaker. Contact him at

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