California’s Monarch Butterflies

Tuesday December 1, 2015
Posted by

by Donna M. Walker

Protecting California’s Monarch Butterflies

Monarch Butterfly (Danaus plexippus) Male – Note the two black spots on the bottom wings.

Monarch Butterfly (Danaus plexippus) Male – Note the two black spots on the bottom wings.

Black and orange wings soar through the air for thousands of milesthen flutter gracefully towards the ground where they find rest in southern and central California trees.

If there is one insect, because of its beauty, that has captured the heart of Californians, it’s the Monarch Butterfly

… unless of course, you happen to be an entomologist, then you probably find beauty in Jerusalem crickets – as only an entomologist could and would!

Map of Monarch Butterflies Fall Migration

Map of Monarch Butterflies Fall Migration

Migrating Monarchs

In southern California, once fall approaches, Monarch butterflies take refuge from their long journey south to the sheltering trees of San Diego, Orange, and Los Angeles Counties.

This little beauty, I mean handsome fellow, was captured by the camera on Bass Island, Lake Erie, Ohio.

There are two populations of Monarch butterflies in North America that are separated by the Rocky Mountains; each with different migration patterns.

The Monarchs east of the Rockies migrate south to spend their winters in Mexico.

West of the Rockies, here in California, Monarchs migrate from Canada to the coast of central and southern California where they overwinter.

Wintering Monarchs

Overwintering Monarchs cling together in bunches among California trees. On sunny days, you may see them flying around neighborhoods, gathering nectar and water to drink.

“Which way is up?” – Monarch caterpillar underneath a leaf.

“Which way is up?” – Monarch caterpillar underneath a leaf.

As the weather warms, Monarch butterflies instinctively know it is time to migrate. Females fly north, seeking milkweed to lay their eggs.

A Monarch female can lay more than one egg, depending on how many times she mated!

Monarch Life Span

Overwintering Monarch butterflies can live 6 to 8 months, whereas spring and summer Monarchs live only 2 to 6 weeks.

Baby Monarchs born in the right season are programmed to continue the “Great Migration” cycle from Canada to Southern California and back again.

It is estimated that it takes four generations of Monarch butterflies to make the entire round trip. Consider how amazing these delicate winged creatures are able to fly 50 to 100 miles a day!

How to tell the difference between a female and a male Monarch butterfly: The male Monarch can easily be distinguished from the female by two black spots on the insect’s hind wings and thinner black webbing within the wings.  The female has much fatter webbing and no spots.

Mating and Reproduction

Springtime is a flurry of mating activity; unlike drone bees that die after mating, both male and female Monarch butterflies get to mate several times.

Roosting Monarch Butterflies Overwintering

Roosting Monarch Butterflies Overwintering

Courtship starts when a male Monarch takes to the air to look for a willing female.

If unwilling, sometimes the male forces her to the ground to copulate but since only 30% of copulation actually occurs, it appears that female Monarchs can get away if they want too.

During copulation, the Monarchs will remain attached for 30 – 60 minutes!

The more the female mates, the more eggs she lays. Sadly, mother Monarchs soon die after they’ve laid their eggs.

Eggs are laid on the underside of the milkweed plant; after they’ve hatched, baby Monarch larvae have a whole plant to feed upon. And feed they do! –

Monarch caterpillars have voracious appetites, eating 2700 times their initial body weight within a two week period!

Female Monarch Butterflies lay eggs underneath leaves of the milkweed plant.

Female Monarch butterflies lay eggs underneath leaves of the milkweed plant.

After two weeks of gorging on milkweed, the Monarch caterpillar attaches itself to something sturdy like a tree branch or a fence; then it sheds its skin and develops a hard, outer green and gold-colored skin, called a chrysalis or pupa.

During the next two weeks (10-14 days) a metamorphose occurs and the black and yellow striped caterpillar grows wings, changing into a beautiful orange and black Monarch butterfly.

Are Monarch Butterflies Ever Pests?

Adult butterflies are not pests but beautiful and beneficial garden insects.

These beautiful butterflies flutter about, gathering nectar, and help honeybees pollinate our plants … but what about butterfly baby larvae – caterpillars?

Monarch Butterfly’s Cycle of Life

Monarch Butterfly’s Cycle of Life

Monarch caterpillars feed only on milkweed, native to California and the rest of North America, which means – one doesn’t need to worry about caterpillars ruining ornamental plants.

These baby butterfly larvae eat all parts of the milkweed plant; leaves, flowering buds, including the milky juice from the stems of the plant.

So, since they only feed on milkweed – Monarch baby butterfly caterpillar larvae (try to say that real fast!) for sure, are not pests.

Monarch Caterpillar – Beautiful yellow and black stripes make the baby larvae easy to identify.

Monarch Caterpillar – Beautiful yellow and black stripes make the baby larvae easy to identify.

Milkweed and Monarch Butterflies

Over the last several years, Monarch butterflies have decreased in numbers due to the loss of their milkweed habitat.

Development has taken over much of North America’s native landscapes where milkweed naturally grows .

In California, we have several different types of milkweed plants that Monarch butterflies rely on to lay their eggs (usually on the underside of a leaf) and for their larvae to feed on, once the eggs hatch.

California Narrowleaf Milkweed – What Monarch Caterpillars Eat

California Narrowleaf Milkweed

Milkweed is not just a food source for Monarch caterpillars but it actually protects both caterpillar and butterfly from predators.

Once caterpillars eat the milky juice of milkweed plants, they become terrible tasting to birds and other predators.

The toxins in milkweed protects Monarchs in both their caterpillar and adult stages of life.

Monarch Butterfly Imposters

Digital painting of a Queen Butterfly (Danaus gilippus) by Donna M. Walker

Digital painting of a Queen Butterfly (Danaus gilippus) by Donna M. Walker

Other butterflies, such as the Viceroy Butterfly, have developed markings on their wings to mimic a Monarch’s – a survival strategy that tricks its predators into thinking they are just as distasteful as a Monarch butterfly.

But Viceroy butterflies do not eat milkweed; also, a closer look reveals differences in wing patterns and the number and size of white dots.

Viceroy Butterfly (Limenitis archippus) Monarch Mimic

Viceroy Butterfly (Limenitis archippus) Monarch Mimic

However, there are milkweed eaters which predators will avoid besides the Monarch butterfly, such as the Queen Butterfly.

This butterfly is also orange and black and taste terrible to its predators.

The beautiful Queen butterfly is rightly named – she wears a solid cloak of orange with irregular white spots, like snowflakes, on her wings, and black trim, giving this butterfly a very “queenly” appearance.

Saving Monarch Butterflies

How can we help? One way to ensure the survival of Monarch butterflies is to plant clusters of milkweed in your yard.

Another is to begin using Organic Pest Control and IPM (Integrated Pest Management) Methods in your garden landscape.

Flower Fly

Flower Fly

Milkweed often harbors pests that can ruin a Monarch caterpillar’s meal and threaten its life. Natural predators of the caterpillar are syrphid flies, robber flies, and parasitic wasps, just to name a few.

Although Monarch caterpillars taste terrible after consuming juice from milkweed, their predators still try to come after them.

If a caterpillar is threatened, it drops to the ground and “plays possum” but if it falls too far from the milkweed plant, and loses its way, the baby caterpillar will perish. It needs milkweed to survive!

Aphids Attract Predators

Aphids can become a problem because they attract a Monarch’s predators.

You can eliminate aphids by hosing the plant or using a spray bottle with a little dish soap mixed with water but after a few minutes, make sure to rinse with fresh water so the soap doesn’t burn the leaves.

Aphids attract predator insects that destroy Monarch caterpillars.

Aphids attract predator insects that destroy Monarch caterpillars.

Pesticides may be necessary if your milkweed has a major aphid infestation. Hearts Pest Management has organic methods for treating and keeping your plants free of aphids.

Syrphid flies will lay their eggs on infested plants with aphids so that their own larvae can feed on the aphids. Besides aphids, syrphid fly larvae will eat young Monarch caterpillars by sucking their insides out and leaving nothing but exoskeletons!

Also, make sure your milkweed plants are densely spaced, just in case baby Monarch caterpillars have to drop and “play possum,” then they’ll be able to find their way back to their host plant.

Where to See Monarch Butterflies

After two weeks of being closed up in a cocoon, this Monarch butterfly will be free to fly.

After two weeks of being closed up in a cocoon, this Monarch butterfly will be free to fly.

Beginning in the month of November, you can view overwintering Monarch butterflies in our sunny, southern California cities.

When next you see a Monarch, think about the amazing journey these little creatures make each year.

Oh, and maybe plant some milkweed in your garden. …

Here are just a few of southern California’s roosting areas for overwintering Monarchs:

San Diego: Grape Street Park, Balboa Park Huntington Beach: Huntington Central Park Long Beach: El Dorado Nature Center

Author’s Note:

Since I started writing the blog for Hearts Pest Management, I’ve always wanted to write about butterflies. …

There is a certain element of freedom and abandonment that I imagine is mine when I see a butterfly flitting about from flower to flower, across streets, and throughout meadows.

One reason butterflies fascinate me is because I have been referred to (over the years by various co-workers) as a butterfly. When I’ve asked why, I was told it’s because I have a “delicate and sensitive nature” …

…but guess what? Butterflies may look delicate but are so strong and persevering, they can fly through prevailing winds!

Donna M. Walker

Donna M. Walker

References / Photos and Design:

Thanks to Trish Kydd for photos of the chrysalis, caterpillar, and evolving Monarch butterfly which she nurtured in her garden.

Photo Editing and Design by Donna M. Walker

Schoenherr, Allan A. 1991. A Natural History of California. Berkeley: University of California Press.; Viceroy; and Queen butterflies USDA Forest Service, 2013. Monarchs and Milkweed. Online: Where to See Overwintering Monarchs. Online: North American Butterfly Association. Online:

City Services for Pest Control in Los Angeles
Agoura Hills Northridge
Alhambra Pacific Palisades
Arcadia Palos Verdes Estates
Beverly Hills Pasadena
Burbank Pomona
Calabasas Rancho Palos Verdes
Cerritos Redondo Beach
City of Industry Reseda
City of Los Angeles Rolling Hills Estates
Claremont San Marino
Culver City Santa Fe Springs
Cypress Santa Monica
Diamond Bar Sherman Oaks
El Monte Sylmar
El Segundo Tarzana
Encino Temple City
Glendale Toluca Lake
Granada Hills Torrance
Hacienda Heights Venice
Hidden Hills Walnut
Hollywood West Covina
La Verne West Hollywood
Long Beach West Los Angeles
Malibu Westlake Village
Manhattan Beach Whittier
Marina Del Rey Woodland Hills
North Hollywood
City Services for Pest Control in Orange County
Aliso Viejo Laguna Hills
Anaheim Laguna Niguel
Brea Lake Forest
Buena Park Los Alamitos
Capistrano Beach Mission Viejo
City of Orange Newport Beach
Corona Del Mar Orange
Costa Mesa Rancho Santa Margarita
Dana Point Rossmoor
Fountain Valley San Clemente
Fullerton San Juan Capistrano
Garden Grove Santa Ana
Huntington Beach Tustin
Irvine Villa Park
La Habra Westminster
Laguna Beach Yorba Linda
City Services for Pest Control in San Diego
4S Ranch Rancho Penasquitos
Poway Scripps Ranch
Rancho Bernardo
Descanso Ramona
Julian Santa Ysabel
Pine Valley
Bonsall Hidden Meadows
Escondido Pauma Valley
Fallbrook Valley Center
Carlsbad Pacific Beach
Coronado Point Loma
La Costa San Ysidro
Mira Mesa The City of San Diego
Otay Mesa
Cardiff by the Sea Oceanside
Carmel Valley Rancho Santa Fe
Del Mar San Marcos
Encinitas Solana Beach
La Jolla Vista
Alpine Imperial Beach
Bonita Jamul
Chula Vista La Mesa
East Lake Chula Vista Lakeside
El Cajon Santee



Add Your Own Comment: