Gardeners who cultivate butterflies are a growing breed

LOS ANGELES

Summer begins with the appearance of the butterflies. The weather warms and suddenly there they are, swirling past on their way to court, mate and frolic.

For the most enraptured gardeners, the spectacle is so thrilling that they've ripped out plants that they like and relandscaped with plants that butterflies need. Where once they fought caterpillars with insecticides and thistles with weed killers, now they coddle worms and pamper weeds in an effort to nurture the splendid winged adults.

They are part of a growing breed: butterfly gardeners. For them, butterflies are more than an air show. They are a measure of the most profound seasonal tempos. No animal's survival and habits are more directly bound up with the life of plants.

As with so many horticultural trends, butterfly gardening came out of England. It first took hold here in the early 1970s, led by the Xerces Society and the Sierra Club, says Julian Donahue, assistant curator emeritus of the Natural History Museum of Los Angeles County and for 23 years the man in charge of the museum's moth and butterfly collection. By 1976, Donahue was publishing articles in botanical journals urging gardeners to create habitats.

Four years ago, these articles morphed into a Natural History Museum booklet, "Butterfly Gardening in Southern California," which is now the starter book for beginners. Donahue meets for an interview on a chilly, gray day that, as the calendar has it, is the first official day of summer. He expects a good show of butterflies this year, but so far they are nowhere to be seen.

"Butterflies are cold-blooded. They need heat to fly," he says.

So we gather in the butterfly house of the museum. As he reaches for a monarch, gently gripping it by its body so it doesn't fly away (don't try this at home), an audience of children gather around him. They can smell a good teacher. Plus, he has what seem godlike privileges: He's the only person the museum staff allows to handle the insects.

"The original butterfly gardens only had nectar plants," he says. "These are great for butterflies. But then people realized that butterflies don't materialize out of thin air. You really have to have what the butterfly caterpillars eat."

Butterfly life cycles

To know what to plant, it helps to understand the life cycle of butterflies, he says. They are first deposited onto plants as eggs, out of which hatch tiny caterpillars. The first thing an emerging caterpillar eats is its shell. It then proceeds to eat 20 times its body weight in leaves. These little "self-stuffing sausages" will shed their casings five times before it's time to transform yet again, into pupa.

Pupa are intermediate beings, not caterpillars, not butterflies, but tightly packaged gobs of protoplasm called chrysalids. These can dangle from a plant or the eave of a house, or nestle among leaves and grass. Only the sharpest eyes can usually spot them: 150 million years of evolution has equipped them to look almost exactly like dead leaves. Inside, winged butterflies will be forming.

When adult butterflies first emerge from these casings, they are drowsy and damp. This is the time that they are most likely to settle on us, pose for a photograph, bask on a flower. Once they are on the wing, it's all business.

"If they're males, they're looking for females," Donahue says. "If they're females, they're looking for food plants where they can lay their eggs."

Butterflies are promiscuous, but also strict practitioners of family planning. The females will mate repeatedly, then store the sperm separately from the eggs. They only fertilize the eggs once they've found a spot suitable for their young. Finding the right plant can amount to an exhaustive shopping trip. Most butterflies will lay eggs on only one or two types of plants. Anise swallowtails like fennel; California sisters, coastal live oaks; marine blues, "Cape Plumbago" and locoweed; red admirals, nettles; monarchs, milkweed; and Gulf fritillaries, passion vines.

How do these little bugs find the exact plants that they need in our big crazy urban grid? "They're really good botanists," says Donahue. "They can detect a food plant by infrared radiation of the plant or by the smell. Every plant has a chemical signal."

Generations of butterflies

What we take to be the same butterflies throughout the summer are probably several generations. Most adults live four to eight weeks. The exception comes for the handful of Western butterflies that migrate, such as monarchs. The generation born when the population is programmed to migrate to the Sierra in February and back to coastal over-wintering sites in October can live six or seven months.

No rule is perfect. Sometimes normally short-lived butterflies suddenly qualify for gold watches. A change of season and genetic flukes can trigger a long dormancy. These dormant specimens might live many months, or even years, as eggs, and months as caterpillars and even as adult butterflies. Something will have directed their metabolisms to slow to near standstill.

Fourth-grade science teacher Brandon Scully, whose class at Second Street Elementary in Los Angeles' Boyle Heights district rears caterpillars in the school garden, has reported: "Some of the adults come right out. Others go a whole season, and they don't come out until the next year. All of a sudden on a bright day in January, boop, one will come out.''

On hearing this, Donahue grins delightedly. This is nature at its most resourceful, he says. Time-release mechanisms in eggs allow a successive release of the species throughout the year. "Some at least will succeed,'' he says. "That's how they survive drought and forest fires.'' Some desert varieties lay dormant until a rain, when the food plant for the caterpillars will leaf out. "It really is an exquisite web of interrelatedness.''

Supporting caterpillars

In home gardens, the interrelatedness is no less exquisite. Females find the right caterpillar plants, whether it's radishes or parsley. As the leafy spring greens die off and nectar flowers bloom, the larvae rapidly evolve and the butterflies appear. The trick, says Donahue, is to plant enough native plants to support the caterpillars.

But if you don't go whole hog replanting your garden, Donahue advises, borderline sloth is the next best thing.

"One of the best friends of butterflies is a lazy gardener,'' he says.

Letting the fennel go to seed and passion vine run amok is creating a breeding ground for swallowtails and Gulf fritillaries. If you leave leaf mulch, don't use insecticides and don't cannon-blast plants with water from a hose, the more likely you are to have butterflies.

Landing-pad flowers

As for good nectar plants, those are easy. Evolution made butterflies picky about caterpillar plants, but adults will drink nectar where they find it. Shape is the important factor. While hummingbirds can suspend themselves in air to drink from tubular flowers, butterflies need a flat, upward facing flower that they can hold on to. Native yarrow, ceanothus, thistles, daisies, zinnias and marigolds, and buddleia and milkweed are all excellent nectar plants.

Butterflies are so tasty to so many predators, including lizards, cats, birds and spiders, that they have evolved amazing defenses, from spines on caterpillars to a taste for the leaves of poisonous plants. While milkweed nectar isn't poisonous, milkweed leaf is, at least to birds. It won't kill them, but they will feel like they ate potato salad at a church social. The monarch caterpillar's exclusive diet of milkweed leaves has made its flesh sickening to birds, and its orange and black coloration synonymous with a warning signal. The birds' aversion is so hard-wired that similarly colored butterflies, such as Gulf fritillaries, enjoy vicarious immunity, even though they don't eat milkweed as caterpillars.

Donahue explains this to the children as if the monarch is speaking. "Look at me,'' he says. "I'm brightly colored! I'm poisonous!''

As he releases the demonstration monarch and it flutters off, a child presents him with a wing of a Gulf fritillary found among the mulch. Taking a pen, Donahue flakes off one of the tiny scales that cover the wings.

"This,'' he says, "is as close as you'll ever get to pixie dust.''