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These butterflies are sure sign of autumn

Thousands of Orange Sulphur butterflies looking for clover

Sacramento Digs Gardening
BY Debbie Arrington PUBLISHED SEP 29, 2021

Orange Sulfur butterfly

The Orange Sulphur butterfly often lives in alfalfa fields but disperses when the crop is harvested. (Photo courtesy Art Shapiro's Butterfly Website)

“Where did all these yellow butterflies come from?” My neighbors want to know.

Out of nowhere, thousands of brightly colored little butterflies suddenly appeared this week in Sacramento’s Pocket and Greenhaven neighborhoods. Barely 2 inches across, these mini dazzlers flit over lawns and streets in crazy zigzag patterns. (A couple got stuck on my Volkswagen’s grill.)

Were they migrating hundreds of miles like Painted Ladies or Monarchs? Did our summer heat cause a caterpillar explosion? Was this another sign of climate change?

No, most likely somebody just mowed a Yolo County field. And they’re not really yellow – they’re orange.

Butterfly on yellow daisy-like flower

An Orange Sulphur butterfly rests on a sunchoke flower. (Photo:

Debbie Arrington)

Our colorful wave was a lot of displaced Orange Sulphur ( Colias eurytheme ) butterflies, according to UC Davis butterfly expert Dr. Art Shapiro, who had been contacted by more than one Pocket resident. “(It’s) a very abundant species that breeds on cultivated alfalfa as well as various wild legumes,” he said. “They disperse in all directions when the rancher cuts the alfalfa and then often show up in urban areas. I suspect the source is an alfalfa field across the river in Yolo County.”

After their home is mowed down, the butterflies go looking for more food – particularly clover lawns. Nicknamed “Alfalfa Butterfly,” the Orange Sulphur prefers flowers in the pea family – alfalfa, clover, vetch, lupine, etc. – but will feed on sunflowers and other members of the aster family as well as milkweed and other high-nectar flowers.

“They may (lay eggs) on clover in lawns but the larvae will not do any damage,” Shapiro said. “The first generation or two in spring breed(s) on annual vetches ( Vicia species). They switch to alfalfa when the vetch dries up.”

That erratic, bouncing, up-and-down flight pattern is a way to avoid getting eaten themselves. Predators have a hard time grabbing them in mid-flight.

When feeding on a flower, Orange Sulphur butterflies usually keep their wings together, displaying menacing little “eyes” on the undersides of their wings. (That’s another defense tactic.) While the underside has spots, the wings’ topside usually has black borders, but that can vary.

With enough food and warmth, this butterfly species can remain active year round, making it one of our most common butterflies, Shapiro said. “This is also our most variable butterfly, seasonally and individually.”

In winter, Orange Sulphurs are smaller with more subdued coloring. In summer, they’re bigger and brighter. Another twist, many females are more cream-colored than orange or yellow.

In early autumn, they’re most numerous – or appear that way – because that’s when alfalfa is often harvested.

“By the way, the very similar Colias lesbia does all the same things in Argentina,” Shapiro noted. “Dispersers from alfalfa in the Paraná Delta often show up in downtown Buenos Aires and visit flowers in window boxes on high-rise apartment buildings!”

For more on Orange Sulphur butterflies: https://butterfly.ucdavis.edu/butterfly/colias/eurytheme .

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GENERAL GARDENING

An article about gardening.

Keywords:

milkweed Sacramento nectar plants asters fields native insects alfalfa gardening sunflowers autumn Orange Sulphur butterflies flowers peas

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Remember to water early and deeply; your garden depends on you.

* It’s not too late to add a splash of color. Plant petunias, snapdragons, zinnias and marigolds.

* From seed, plant corn, pumpkins, radishes, winter squash and sunflowers.

* Keep your vegetable garden watered, mulched and weeded. Water before 8 a.m. to reduce the chance of fungal infection and to conserve moisture.

* Water, then fertilize vegetables and blooming annuals, perennials and shrubs to give them a boost.

*Fertilizing flowering plants every other week will extend their bloom. Give vegetable plants bone meal or other fertilizers high in phosphate to stimulate more blooms and fruiting.

* Don’t let tomatoes wilt or dry out completely. Give tomatoes a deep watering two to three times a week. Harvest vegetables promptly to encourage plants to produce more. Squash especially tends to grow rapidly in hot weather. Keep an eye on zucchini.

* If your melons and squash aren’t setting fruit, give the bees a hand. With a small, soft paintbrush, gather some pollen from male flowers, then brush it inside the female flowers, which have a tiny swelling at the base of their petals. (That's the embryo melon or squash.) Within days, that little swelling should start growing.

* Pinch back chrysanthemums for bushy plants and more flowers in September.

* Remove spent flowers from roses, daylilies and other bloomers as they finish flowering.

* Pinch off blooms from basil so the plant will grow more leaves. New leaves have the best flavor.

* Cut back lavender after flowering to promote a second bloom.

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Plant a fruit tree now -- for later

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Time to give vegetable seedlings some more space

Ways to win the fight against weeds

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Dec. 16: Add asparagus to your edible garden

Dec. 9: Soggy soil and what to do about it

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Nov. 25: It's late November, and your peach tree needs spraying

Nov. 18: What to do with all those fallen leaves?

Nov. 11: Prepare now for colder weather in the edible garden

Nov. 4: Plant a pea patch for you and your garden

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July 29: Why won't my tomatoes turn red?

July 22: A squash plant has mosaic virus, and it's not pretty

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June 24: Weird stuff that's perfectly normal

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June 10: Battling early-season tomato pests

June 3: Make your own compost

May 27: Where are the bees when you need them?

May 20: How to help tomatoes thrive on hot days

May 13: Your plants can tell you more than any calendar can

May 6: Maintain soil moisture with mulch for garden success

April 29: What's (already) wrong with my tomato plants?

April 22: Should you stock up on fertilizer? (Yes!)

April 15: Grow culinary herbs in containers

April 8: When to plant summer vegetables

April 1: Don't be fooled by these garden myths

March 25: Fertilizer tips: How to 'feed' your vegetables for healthy growth