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What the sources say

Monarch ButterflyDanaus plexippus

Every figure, record and mechanism on the Monarch Butterfly profile was written from a source, and this is the working table behind it: 44 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

Profile updated

Source
01

Walker et al. 2022

Walker et al. (2022). Danaus plexippus. The IUCN Red List of Threatened Species 2022: e.T159971A219149911.

The page saysThe IUCN Red List rates the species Least Concern
The source saysLeast ConcernNote: category via GBIF copy; assessment year not in cached text, so left out of the body

Source
02

U.S. Fish & Wildlife Service

Monarch (Danaus plexippus). U.S. Fish & Wildlife Service.

The page saysmakes one of the longest known insect migrations in the world
The source saysThe monarch's journey is one of the longest known insect migrations in the world.
The page saysA butterfly of about half a gram that wears milkweed poison as armor
The source saysOn average, adult monarch butterflies weigh about half of a gram, which is less than the weight of a paperclip.Note: tagline; 'on average' per source
The page saysEastern monarchs migrate up to 3,000 miles using a sun compass
The source saysThe eastern population of monarchs travel up to 3,000 miles during migration traveling from Canada, through the U.S. and down to MexicoNote: stats.superpower; compass in the next claim
The page saysFields, roadsides, wetlands and gardens with milkweed, across the Americas
The source saysWhether it’s a field, roadside area, open area, wet area or urban garden, milkweed and flowering plants are needed for monarch habitat.Note: stats.habitat; Americas from the range claim below
The page saysEastern North American monarchs fly up to 3,000 miles each fall, from Canada through the United States to Mexico
The source saysThe eastern population of monarchs travel up to 3,000 miles during migration traveling from Canada, through the U.S. and down to Mexico
The page saysThe trip may last more than two months
The source saysa trip that may last more than two months
The page saysthe longest single-day flight recorded for a tagged eastern monarch is 265 miles
The source saysThe longest single day flight of a tagged eastern North American monarch was recorded at 265 miles.
The page saysA monarch caterpillar eats milkweed
The source saysMonarch butterflies require healthy and abundant milkweed plants for both laying eggs on and as a food source for caterpillars.
The page saysBy consuming it, monarchs obtain toxins called cardenolides that defend them against predators
The source saysBy consuming milkweed plants, monarchs obtain toxins, called cardenolides, that provide a defense against predators.
The page saysThe adult's bright orange wings with a black border act as a warning that eating one can be toxic
The source saysAdult monarch butterflies are large and conspicuous, with bright orange wings surrounded by a black border and covered with black veins. ... The bright coloring of a monarch serves as a warning to predators that eating them can be toxic.
The page saysAn adult monarch has a wingspan of 3 to 4 inches (7 to 10 cm)
The source saysWingspan: 3 to 4 inches (7 to 10 cm)
The page saysOn average it weighs about half a gram, less than a paperclip
The source saysOn average, adult monarch butterflies weigh about half of a gram, which is less than the weight of a paperclip.
The page saysCaterpillars have black, yellow and white stripes and reach 2 inches (5 cm) before they pupate
The source saysMonarch caterpillars, or larvae, have black, yellow and white stripes and reach lengths of two inches before metamorphosis. ... Larval length: 2 inches (5 cm)
The page saysor turn into a chrysalis
The source saysMonarch caterpillars then pupate into a green and gold chrysalis
The page saysMost breeding adults live about two to five weeks
The source saysMost breeding adult butterflies live approximately two to five weeks
The page saysOverwintering adults that enter reproductive diapause
The source saysoverwintering adults that enter into reproductive diapause can live six to nine months
The page sayscan live six to nine months
The source saysoverwintering adults that enter into reproductive diapause can live six to nine months
The page saysa state of suspended reproduction
The source saysgo into a state of suspended reproduction, known as diapause
The page saysMonarchs are native to North and South America and have spread to many other places, including Australia, New Zealand and parts of the Iberian Peninsula
The source saysMonarchs are native to North and South America but have since spread to many other locations where milkweed and suitable temperatures exist, including Australia, New Zealand and portions of the Iberian Peninsula.
The page saysNorth America's migratory monarchs form two populations
The source saysNorth American migratory monarchs are divided into eastern and western populations.
The page saysMost eastern monarchs winter in oyamel fir forests in the mountains of central Mexico
The source saysFor the eastern North American population, most monarchs overwinter in oyamel fir tree roosts located in mountainous regions of central Mexico
The page sayswestern monarchs, west of the Rocky Mountains, winter mainly in California
The source saysMonarchs living west of the Rocky Mountains in North America primarily overwinter in California
The page saysWhere milkweed grows all year and temperatures suit them, monarchs in many areas live and breed year round without migrating
The source saysWith the year-round presence of milkweed and suitable temperatures, monarchs in many areas of the their worldwide range, including parts of North America, live and breed year round. Many of these non-migratory monarchs
The page saysIn early spring the survivors end their pause in breeding, mate at the overwintering sites and then fly back through the breeding grounds
The source saysIn early spring, surviving monarchs break diapause and mate at the overwintering sites before dispersing. The same individuals that undertook the initial southward migration begin flying back through the breeding grounds.
The page saysAfter several generations of offspring, a new generation makes the next fall trip for the first time
The source saysAfter several generations of monarch offspring in the spring and summer, a new generation begins the fall migration for the first time.
The page saysFemales lay eggs on milkweed plants, the only food the caterpillars can eat
The source saysthey lay eggs on milkweed plants as that is the only food the caterpillars can eat
The page saysAdults are less picky and sip nectar from many flowers
The source saysAdult monarchs feed on the nectar of many flowers during breeding and migration

Source
03

San Diego Zoo Wildlife Alliance

Monarch Butterfly. San Diego Zoo Wildlife Alliance.

The page saysMilkweed as a caterpillar, flower nectar as an adult
The source saysAs caterpillars, monarchs rely on native milkweed species to survive. Once they transform into adult butterflies, monarchs feed on nectar from flowering plants.Note: stats.diet
The page saysA year brings four to five generations, and the late-summer and fall ones are the ones that migrate
The source saysMonarchs are multigenerational, cycling through four to five generations ... The later generations, which emerge in the late summer or fall, migrate north or south.
The page saysThe monarch's two main bird predators, black-backed orioles and grosbeaks, seem immune to the toxins and eat monarchs in large numbers, though that may be because the toxins decay during migration and overwintering
The source saysTheir two main avian predators, black-backed orioles and grosbeaks, seem to be immune to monarch toxins and consume the insects in large numbers; however, this may be due to the decay of monarch toxins during their migration and overwintering.
The page saystags: pollinator
The source saysAlong with other pollinators like bees, monarchs play an important role in the ecosystem, dispersing flower pollen as they flutter from plant to plant.Note: #998

Source
04

Taylor 2017

Taylor (2017). Biology of the Monarch Butterfly. Kansas School Naturalist 62(2), Monarch Watch.

The page saysIn early studies a blue jay that ate a monarch vomited shortly afterwards because of the cardenolides, and that bird learned never to eat another
The source saysEarly studies of Monarchs showed that when a blue jay ate a Monarch butterfly, it vomited shortly afterwards due to the cardenolides. That bird also learned to never eat another Monarch butterfly.Note: one bird in early studies; not generalised

Source
05

Merlin, Gegear & Reppert 2009

Merlin, Gegear & Reppert (2009). Antennal Circadian Clocks Coordinate Sun Compass Orientation in Migratory Monarch Butterflies. Science.

The page sayswhose eastern migrants steer by the sun
The source saysEastern North American monarch butterflies (Danaus plexippus) use a time-compensated Sun compass to aid navigation to their overwintering grounds in central Mexico.Note: tagline; eastern population
The page saysEastern monarchs migrate up to 3,000 miles using a sun compass
The source saysEastern North American monarch butterflies (Danaus plexippus) use a time-compensated Sun compass to aid navigation to their overwintering grounds in central Mexico.Note: stats.superpower; the 3,000 miles is covered by the fws-monarch entry above
The page saysMigrating eastern monarchs use a time-compensated sun compass to find their overwintering grounds in central Mexico
The source saysEastern North American monarch butterflies (Danaus plexippus) use a time-compensated Sun compass to aid navigation to their overwintering grounds in central Mexico.
The page saysA 2009 study found that the antennae are necessary for proper sun compass orientation, that antennal clocks exist in monarchs, and that they likely provide the primary timing mechanism
The source sayswe show that the antennae are necessary for proper time-compensated Sun compass orientation in migratory monarch butterflies, that antennal clocks exist in monarchs, and that they likely provide the primary timing mechanism for Sun compass orientation.Note: 2009 is the reference year (merlin-2009)
The page saysThe time compensation comes from a circadian clock, an internal body clock
The source saysIt has been assumed that the circadian clock that provides time compensation resides in the brain
The page saysScientists had assumed it sat in the brain, although nobody had tested that directly, and the authors called their antennae findings unexpected
The source saysIt has been assumed that the circadian clock that provides time compensation resides in the brain, although this assumption has never been examined directly. ... These unexpected findings pose a novel function for the antennae
The page saysMigrating eastern monarchs steer by a time-compensated sun compass
The source saysEastern North American monarch butterflies (Danaus plexippus) use a time-compensated Sun compass to aid navigation to their overwintering grounds in central Mexico.Note: vibe.reason animal clause, same source as the body claim "Migrating eastern monarchs use a time-compensated sun compas"
The page saysclocks in their antennae likely provide the timing
The source sayswe show that the antennae are necessary for proper time-compensated Sun compass orientation in migratory monarch butterflies, that antennal clocks exist in monarchs, and that they likely provide the primary timing mechanism for Sun compass orientation.Note: vibe.reason animal clause, same source as the body claim "A 2009 study found that the antennae are necessary for prope"

Source
06

Karageorgi et al. 2019

Karageorgi et al. (2019). Genome editing retraces the evolution of toxin resistance in the monarch butterfly. Nature.

The page saysMany insects that colonized cardiac glycoside plants, monarchs among them, evolved changes in the sodium pump, the cell protein those toxins attack
The source saysinsects from six orders, including the monarch butterfly (Danaus plexippus), that have independently evolved to colonize plants that produce cardiac glycoside toxins 6-11 . Many of these insects evolved parallel amino acid substitutions in the α-subunit (ATPα) of the sodium pump (Na + /K + -ATPase) 7-11 , the physiological target of cardiac glycosides
The page saysIn 2019 scientists used CRISPR gene editing to rebuild the monarch's changes in fruit flies
The source saysWe then performed CRISPR-Cas9 base editing on the native Atpα gene in Drosophila melanogaster flies and retraced the mutational path taken across the monarch lineageNote: 2019 is the reference year (karageorgi-2019)
The page saysTheir triple-mutant "monarch flies" were as insensitive to the toxins as monarch butterflies
The source saysculminating in triple mutant 'monarch flies' that were as insensitive to cardiac glycosides as monarch butterflies.

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.