50 Fun Facts About Monarch Butterfly

In 2009, a batch of monarchs was reared until the adults emerged from their pupae in which unusual location?

The International Space Station hosted the Monarchs in Space project. The insects rode up on Space Shuttle Atlantis and emerged as adults in orbit.

Which Mexican holiday coincides with the arrival of migrating monarchs at their winter forests each autumn?

Day of the Dead celebrations begin just as the eastern monarchs reach their winter forests. Folklore says the butterflies carry the souls of ancestors.

Which toxic wildflower is the only plant monarch caterpillars eat, making the adults foul-tasting to birds?

Milkweed is the monarch's sole host plant, and females lay their eggs on it. Its loss to herbicides is one cause blamed for the butterfly's decline.

Which smaller orange-and-black butterfly mimics the monarch but has an extra black line across each hindwing?

Viceroy butterflies were long thought to be harmless copycats. They are in fact distasteful to predators too, so both species gain from the shared pattern.

What is the name for the hard case in which a monarch caterpillar transforms into an adult butterfly?

Chrysalis is the word for a butterfly's bare pupa. Unlike a moth's, it is not wrapped in a cocoon.

Migrating monarchs hold their course using an internal body clock and the changing position of what?

The Sun moves across the sky all day, so monarchs correct for the hour with a body clock. Scientists call the system a time-compensated compass.

A monarch caterpillar ready to pupate hangs upside down from a silk pad in the shape of which letter?

J is the shape the caterpillar holds for about 12 to 16 hours. Its skin then splits behind the head and is shed within minutes.

Which magazine put the discovery of the monarchs' Mexican winter colonies on its cover in August 1976?

National Geographic ran the story with Catalina Trail on the cover, covered in butterflies. She and Kenneth Brugger had found the colony on a mountain summit in January 1975.

What is the first thing a newly hatched monarch caterpillar eats before it starts on leaves?

Its own eggshell is the caterpillar's first meal. It then chews a small arc-shaped hole in the leaf it hatched on.

The monarch's pale green pupa is studded with small shiny dots in which metallic shade?

Gold dots sit near the bottom of the pupa, with a gold-and-black rim near the top. The shell is soft at first and hardens within about a day.

What do biologists call the monarch's four-stage development from egg through caterpillar and pupa to winged adult?

Complete metamorphosis is shared by all butterflies and moths. Commonly fewer than one in ten monarch eggs and caterpillars survive to finish it.

Which scientific term names the caterpillar stage of the monarch's life cycle, when it does all its growing?

Larva is the stage that hatches from the egg. A monarch caterpillar grows from a few millimeters long to about 4.5 cm before it pupates.

A monarch caterpillar is ringed with bands of black, white and which third bright color?

Yellow bands first appear after the caterpillar's first molt. A newly hatched one is pale and almost translucent, with a large black head.

Adult monarchs feed through which long, straw-like mouthpart that coils up when not in use?

Proboscis is the name of a butterfly's drinking tube. Caterpillars lack one and chew with separate mouthparts instead.

Monarch caterpillars are leaf eaters, but what do the adult butterflies mainly feed on?

Flower nectar from many plants fuels adult monarchs. Asters and goldenrods are major sources during the fall migration.

In warm summer weather, roughly how long does a monarch take to develop from egg to adult butterfly?

About a month is typical: as little as 25 days in summer warmth, stretching to seven weeks in a cool spring. Summer adults then live only two to five weeks.

A monarch caterpillar sheds its skin five times; what are the growth stages between these molts called?

Instars last about three to five days each, depending on temperature and food. The caterpillar's black tentacles start growing in the second one.

Where on a plant does a female monarch usually glue each of her eggs, one at a time?

Underside of a leaf, usually a young one, is the typical place. A female may lay 300 to 500 eggs this way over two to five weeks.

Which marking on each hindwing shows that an adult monarch butterfly is male, not female?

A black spot on each hindwing is a patch of specialized scent scales. Females lack the spots and have thicker black wing veins.

Monarch caterpillars often bite through a leaf vein before feeding to cut off the flow of which sticky fluid?

Latex flows under pressure in the leaf, so the caterpillar feeds above the cut. Older ones notch the leaf stalk so the whole leaf drops to hang vertically.

The monarch sanctuaries of Sierra Chincua and El Rosario are in which Mexican state, west of Mexico City?

Michoacán holds five of the eight colonies in the Monarch Butterfly Biosphere Reserve. At El Rosario, the best known, the butterflies cover about 1,500 trees.

On which high-altitude conifer do millions of monarchs cluster through the winter in central Mexico?

Oyamel fir forests grow between about 2,400 and 3,600 meters up. Their microclimate shelters the butterflies when temperatures fall to freezing.

Overwintering monarchs on the California coast often roost in which introduced tree, even where native trees grow?

Eucalyptus is chosen consistently, though the butterflies show a slight preference for native trees. Well-known roosts include Santa Cruz and Grover Beach.

Which California coastal city sets a $1,000 fine for molesting monarchs during their winter visit?

Pacific Grove holds a Butterfly Parade each October to welcome the monarchs back. Its Monarch Grove Sanctuary sits among residential streets.

Experiments found that the body clock steering a migrating monarch sits in which part of the butterfly?

The antennae keep their own daily rhythm even when removed and studied in a dish. Monarchs without them fly in scattered directions instead of heading south as a group.

Which Canadian zoologist tagged monarchs for decades to learn where the eastern population spent the winter?

Fred Urquhart worked with his wife Norah and hundreds of volunteers, who tagged wings and reported sightings. The search took nearly 40 years.

The monarchs that leave Mexico in spring breed after flying only as far north as Oklahoma and which state?

Texas is where the overwintered generation lays the eggs of the next. Their offspring and later generations carry the migration on toward Canada.

The Monarch Butterfly Biosphere Reserve in central Mexico was added to which international register in 2008?

World Heritage List status came after poet Homero Aridjis, then Mexico's ambassador to UNESCO, won a unanimous vote. In 1986 he had persuaded Mexico's president to protect the wintering sites.

Which butterfly's round trip between tropical Africa and the Arctic Circle is longer than the monarch's migration?

Painted lady butterflies cover about 9,000 miles over as many as six generations, as radar records show. The longest eastern monarch round trip is about 6,000 miles.

Which type of mimicry, shown by the monarch and its look-alike, has two distasteful species share one warning pattern?

Müllerian mimicry replaced the older textbook label, Batesian, after tests showed birds find the look-alike as unpalatable as the monarch itself.

Which steroid toxins do monarch caterpillars store from their food, protecting the adult butterflies?

Cardenolides act on the heart much as digitalis does. An adult keeps its most potent doses in the abdomen, to deter predators that tear off the wings first.

What is the term for an animal advertising its toxicity with bold colors, as the orange-and-black monarch does?

Aposematism was named by Edward Poulton for Alfred Russel Wallace's idea of warning coloration. Monarchs show it as striped caterpillars as well as winged adults.

OE, a parasite that can leave monarchs too weak to expand their wings, is what kind of organism?

A protozoan named Ophryocystis elektroscirrha, it spreads as dormant spores that fall from a female onto her eggs and nearby leaves, where hatching caterpillars swallow them.

Which naturalist first described the monarch butterfly, in the 1758 edition of his Systema Naturae?

Carl Linnaeus placed it in Papilio, the single genus he used for every known butterfly. It was moved to a new genus in 1780.

What is the monarch butterfly's scientific name, drawn by its describer from figures of Greek myth?

Danaus plexippus takes its second name from Plexippus, one of the fifty sons of Aegyptus in Greek myth. In Homeric Greek the name means one who urges on horses.

By what name is the monarch butterfly commonly known in Australia, where it has lived since about 1871?

Wanderer is its usual Australian name. The earliest Sydney sighting was in 1871, and the population took hold only once its food plants were introduced too.

Monarchs belong to which insect order, whose Greek name means scale wing, with all other butterflies and moths?

Lepidoptera are named for the tiny colored scales that cover their wings and bodies. Those scales give a monarch's wings their orange and black.

Which close relative of the monarch, a darker brown butterfly of the southern United States, also has a royal name?

Queen butterflies belong to the monarch's genus but lack its bold black wing stripes. A third look-alike relative is called the soldier.

Monarch eyes can detect which kind of light, invisible to humans, that may help them orient to the sky?

Ultraviolet receptors also sit along the upper rim of the eye, where they are thought to read polarized skylight. Orange filter pigments in the eye sharpen its color vision.

What is the name for the paused reproductive state that lets fall-migrating monarchs survive until spring?

Diapause marks the generation that flies south, which lives about eight times longer than its parents and grandparents. Unlike most insects in that state, the butterflies stay active.

What happens to a monarch's green pupal shell in the final hours before the adult butterfly emerges?

It turns transparent, so the orange and black wings show through. About a day earlier the shell first takes on a bluish tint.

Like other butterflies, a monarch has taste receptors on its mouthparts and on which other body part?

Its feet carry chemoreceptors that work only on contact. An egg-laying female uses them to check that a leaf will feed her caterpillars before she lays.

Besides basking, what do monarchs do to warm their bodies to the 86 °F they need for flight?

Monarchs shiver their wings rapidly to generate heat. Too much warmth is a danger as well: temperatures above 95 °F can kill their caterpillars.

Monarch Watch, whose volunteers have tagged more than a million monarchs, is run from which American institution?

University of Kansas hosts the program, whose color-coded tags are glued to a monarch's wing. It also registers gardens planted for the butterflies as Monarch Waystations.

Which US president set up a Pollinator Health Task Force after monarch numbers sank to a record low?

Barack Obama's 2014 memorandum warned of an imminent risk of failed migration. The task force went on to set a target of 225 million eastern monarchs.

Which conservation body listed the migratory monarch as endangered in July 2022, then eased it to vulnerable?

IUCN added the migratory monarch to its Red List in 2022, and a petition the next year moved it down a category. Canada listed the species as endangered in 2023.

Monarch declines are often linked to crops engineered to tolerate which weedkiller, sprayed over Midwestern fields?

Glyphosate-tolerant corn and soybeans let farmers spray growing fields, clearing the wild plants monarchs breed on. A 2019 study, though, suggested those plants were declining before such crops arrived.

Which author's 2012 novel Flight Behavior imagines a huge monarch colony wintering in Appalachia?

Barbara Kingsolver sets the story on a Tennessee farm. A visiting scientist warns that the beautiful arrivals are a symptom of climate change and may not survive the winter.

Which mountain range divides North America's eastern monarchs from the western population that winters in California?

The Rocky Mountains mark the divide, but it is not absolute. Tagging records show the two populations mix, and no genetic difference separates them.

In Mexico each winter, scientists gauge the eastern monarch population by measuring what instead of counting?

Forest area occupied is reported in hectares: about 18 in the winter of 1996-97, but only 0.67 in 2013-14. A single hectare may hold tens of millions of monarchs.