Monarchs Need
Our Help

Learn about the many threats faced by Monarch butterflies and what you can do to help their populations rebound from endangerment. Also learn about their reproduction cycles and feeding habits, and how to build your own Monarch habitat in the desert.

Learn more about Monarchs: Creating Habitats | Reproduction and Feeding

Introduction to Monarch Butterflies

If you are from anywhere in the US, you are probably familiar with the monarch butterfly. It is often the only butterfly people can identify. It’s no wonder these graceful creatures stand out due to their large size and bright orange and black coloring.

But did you know not every orange and black butterfly you see is a Monarch?

orange-black

Differences between Monarchs, Queens, and Painted Ladies

All these butterflies are using Müllerian mimicry. A natural phenomenon where two or more species that are well-defended, often foul-tasting, and share common predators, mimic each other's warning signals, in this case orange and black coloring, to their mutual benefit. The theory states that the resemblance is a protective mechanism because a predator that has learned to avoid one organism with a warning system will avoid all similar organisms. This is thought to be beneficial because sharing a warning signal decreases the mortality caused by sampling by inexperienced predators learning to avoid the signal.

Monarch Butterfly (Danaus plexippus):

When the wings are closed, the fore- and hindwings only have white dots within black borders.
Both fore- and hindwings have very bold black lines creating a “stained glass” look.
Hindwings are lighter orange while forewings are mostly a deep amber.
Slightly larger wingspans result in the ability to glide farther and flutter less.

Queen Butterfly (Danaus gilippus):

Separate species of butterfly not the female of the monarch.
When the wings are closed, look for white dots both within the black borders and on the forewings.
Forewings lack the bold black lines that monarchs are known for.
Fore- and hindwings are more uniformly orange, with a brownish tint to their coloring.
Slightly smaller wingspan result in more fluttering and less gliding

Monarch Caterpillar:

Look for two sets of fine filaments, one pair at the front and one at the rear.
Monarch caterpillars are patterned in bands of yellow, white and black that generally appear similar in thickness.

Queen Caterpillar:

Look for three sets of filaments, two longer pairs toward the front and a shorter pair near the rear.
Queen caterpillars have less even patterning; their thicker black bands contain dabs of yellow, and thin black lines overlay white sections. Faint red may be seen where the filament meets the body.

Painted Lady (Vanessa cardui): Although similar in coloring, the painted lady, has quite a different pattern than the Monarch. It has scalloped orange wings with black patches. The tips of its forewings are black with white splotches. Its underside is a mottled gray, brown, and black with four eyespots. The painted lady is also called the thistle butterfly because it likes thistles and the cosmopolitan butterfly because it is found all over the world.

two-populations

official-response

Two North American Monarch Populations

A remarkable thing about monarch butterflies (Danaus plexippus) is that although it is a single species, it largely exists as two separate populations: one east of the Rocky Mountains and one to the west. There are smaller scattered populations but most of the monarchs on Earth occur within these two populations.

Monarch Butterfly Grove Pismo Beach overwintering.jpg

In the late summer, environmental cues trigger migratory behavior. Monarchs delay reproductive development (this is called diapause) and begin to travel away from their breeding grounds towards their overwintering sites.

Eastern monarchs migrate from as far north as Canada to the oyamel fir (“sacred fir”) forests in the mountains west of Mexico City. During this fall migration, a single butterfly can travel more than 3000 miles.

Western monarchs typically migrate towards California where they overwinter in small forested areas along the Pacific coast from just north of San Francisco south to Baja. While a shorter trip than their Eastern counterparts, it is no less remarkable.

Learn more about Monarch migration patterns

Unfortunately, the North American monarch population has severely declined. Habitat loss, pesticides, disease, climate change, predators, extreme weather, and other man-made factors threaten monarchs.

Ongoing monitoring allows scientists to accurately estimate the overall size and trend of monarch populations. This is done when butterflies are stationary at overwintering sites.

Data collected tells us that in the 1990’s over 700 million monarchs made the journey from Canada to Mexico and over a million overwintered on the Coast of California. The most recent numbers suggest that the Eastern monarch overwintering population in Mexico has declined by approximately 80% and the Western population has fallen even further with an estimated 95-99% decline since the 1980s.

While populations do increase and decrease year to year, the long-term trend is steeply downward showing that the population will not be viable unless appropriate measures are taken to build the population to a more sustainable level.

The official response to Monarch decline

In 2014 the Xerces Society, the Center for Biological Diversity, the Center for Food Safety, and Dr. Lincoln Brower determined that action was needed to save the Monarchs. This coalition petitioned the US Fish and Wildlife Service to protect the monarch as a threatened species under the Endangered Species Act (ESA).

In December 2020, the U.S. Fish and Wildlife Service declared the monarch butterfly warranted but precluded. This decision meant that the monarch met the listing criteria under the Endangered Species Act, but there are only enough resources to focus on higher-priority listing actions.

The good news is that we can come together to help the monarchs, without the USFWS protections afforded endangered species, when we understand the causes and work to mitigate them in our own communities.

Habitat Loss

The loss of milkweed is one of the most significant factors driving the plunge in monarch numbers.
The increased use of herbicides has reduced the abundance of milkweed and nectar plants.
The widespread adoption of herbicide-resistant corn and soybeans has resulted in the loss of more than 100 million acres of monarch habitat in recent years.
Clearing, mowing, and spraying roadsides contribute to the loss of habitat.

Our ever-expanding urban sprawl threatens monarch habitats as well as the planting and spread of invasive plants like fountain grass, stinknet, and sahara mustard.

The monarch butterfly's overwintering sites in Mexico face threats from illegal logging. This logging disrupts the delicate forest microclimate that the butterflies depend on for survival. Meanwhile, on the California coast, development and poor land management practices have destroyed or degraded many areas where monarchs once thrived during the breeding season.

habitat-loss

Insecticides

Culturally, we expect to have perfect insect-free plants, so plants we buy at nurseries are treated with insecticides. A relatively new class of pesticides, neonicotinoids (neonics), is a growing concern for pollinators.

The appeal or concern, depending on how you look at it, is that these pesticides are generally long-lived and systemic. They are absorbed into the plant tissue where they linger as a built-in chemical defense against pests.

Monarchs feeding on an intentionally, or even accidentally treated plant, could be exposed. If exposed to neonics in sufficient quantities, monarchs, pollinators, and other invertebrates will die.

Sublethal effects such as reduced survival and reproductive success, can occur when the dose does not result in immediate death.
When purchasing plants, it is always a good practice to ask whether or not the plants you are buying have been treated with insecticides. If they have been treated, or if the nursery owner does not know, we recommend not buying them.

Do not use insecticides in or around your pollinator habitat. If you need to use chemicals elsewhere on your property, including organic treatments, carefully read and follow the instructions on the label.

In addition to the provided instructions, it’s important to know the best time to spray pesticides to prevent accidental harm to beneficial insects or cause leaf damage.

In general, early morning or evening is the best time to spray because beneficial insects are less active during these times and the hot sun can burn the leaves after spraying.

In hot desert environments, like the Coachella Valley, beneficial insects are active early in the morning so it is best to spray in the evening.

insecticides

aphids

Aphids and Milkweed Bugs

In addition to monarchs, a community of other insects feeds on milkweed. Ignoring them and encouraging natural predators like parasitic wasps to control their populations is best.

Flowering plants with abundant nectar and shallow flower surfaces can attract beneficial predators to your garden. Small insects like to land on flat button-like flowers like the Desert Marigold.

While cute, the ladybug is a ravenous predator. Adult ladybugs eat 50-60 aphids a day. Their larvae eat 10 times that amount making them much more effective predators. In a ladybug's lifetime, they can eat as many as 5000 aphids.

Tiny flowers like those on this Desert Tobacco attract beneficial insects. Having different flower types for them to choose from attracts a variety of insects.

Tiny flower example Desert Tobacco_edite

Dragonflies and damselflies are incredibly fierce predators with a 95% success rate in catching their prey. They keep our gardens pest free consuming a variety of flying insects.

The green lacewing is probably the most beneficial and underappreciated. Green lacewing larvae, also known as the aphid lion, eat many soft-bodied insect pests, including aphids. A single larva can eat over 200 pests per week.

Photo: Lacewing egg

Climate Change

It is not fully possible to predict the impacts of climate change but we do know climate change threatens monarchs in several ways.

Frequent episodes of extreme weather harm the overwintering butterflies clustering in trees for protection against rain and wind.
Climate change threatens the trees in their forest shelters.
Drought in California and other western states reduces milkweed and nectar plants in the west.
Warmer temperatures may increase invasive pests. This may in turn lead to increased pesticide use, which would be detrimental to all wildlife, not just monarchs.

While some effects, like faster caterpillar growth and potential range expansion for some plants, are unclear, the overall impact is likely negative.

climate-change

Biological Threats

As the monarch population shrinks, biological threats such as parasites, diseases, and invasive predators become more significant.

Though the impact of predators on monarchs is poorly understood, researchers believe predation is an increasing problem, especially due to the spread of non-native species such as the red imported fire ant (Solenopsis invicta).

The protozoan parasite Ophryocystis elektroscirrha (OE) that seems to thrive on the nonnative tropical milkweed, Asclepias curassavica, is an additional threat. As best we can tell, OE is not prevalent in hot, dry climates like the Coachella Valley. Regardless, we do not recommend planting tropical milkweed.

biological-threats

Captive Rearing

We love monarchs and find them beautiful. It’s not surprising then that there is a demand for commercially-reared monarchs to be purchased for mass release at weddings or other events.

This is not conservation. This activity can introduce diseases and change the genetic makeup of wild monarchs. The conservation community strongly discourages this practice.

Aside from the commercial activity of captive rearing, some dedicated individuals practice captive rearing at home. Like the commercial side, this practice can increase disease and promotes in-breeding. Sadly, these “indoor butterflies” are less successful at migration because the cues they sense and use for migration are different indoors than in the wild.

In California, you need a Scientific Collecting Permit (SCP) from the California Department of Fish and Wildlife (CDFW) to handle wild monarch butterflies. This includes handling for educational purposes. The permit requirement applies to monarchs wherever they are found in the state, including on private property.

It's illegal to collect, remove, or rear monarchs without an SCP.

The ruling to prohibit touching and rearing monarchs in California is intended to allow nature to proceed without human interference. This includes preventing urban gardeners from protecting caterpillars and chrysalids, putting them into habitats, or raising eggs, caterpillars, or chrysalids indoors.

captive-rearing

What can we do?

Create a monarch habitat.

The most important step you can take to benefit monarchs and other pollinators is to create or improve a habitat that contains native milkweeds and nectar plants.

Participate in community science monitoring programs

Journey North
Monarch Larva Monitoring Project
Western Monarch Milkweed Mapper
Western Monarch Thanksgiving Count
Monarch SOS app by Nature Digger (iPhone and iPad only)
iNaturalist

Resources on monarch conservation

Tell your friends and neighbors what you are doing and why

Certify your habitat as a Monarch Waystation
And the last but very important step... Sit and enjoy your Monarch-friendly desert garden.