Post by OldGreenVulture on Dec 17, 2019 5:12:58 GMT
Monarch Butterfly - Danaus plexippus.
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Superfamily: Papilionoidea
Family: Nymphalidae
Subfamily: Danainae
Tribe: Danaini
Genus: Danaus
Species: Danaus plexippus
The Monarch butterfly (Danaus plexippus) is a milkweed butterfly (subfamily Danainae), in the family Nymphalidae. It is perhaps the best known of all North American butterflies. Since the 19th century, it has been found in New Zealand, and in Australia since 1871 where it is called the Wanderer. In Europe it is resident in the Canary Islands, the Azores, and Madeira, and is found as an occasional migrant in Western Europe. Its wings feature an easily recognizable orange and black pattern, with a wingspan of 8.9–10.2 centimetres (3½–4 in). (The Viceroy butterfly has a similar size, color, and pattern, but can be distinguished by an extra black stripe across the hind wing.) Female Monarchs have darker veins on their wings, and the males have a spot called the "androconium" in the center of each hind wing from which pheromones are released. Males are also slightly larger.
The Monarch is famous for its southward migration and northward return in summer in the Americas which spans the life of three to four generations of the butterfly.
Taxonomy
The common name “Monarch” was first published in 1874 by Samuel H. Scudder because “it is one of the largest of our butterflies, and rules a vast domain”. But the name may be in honour of King William III of England. The Monarch was one of the many species originally described by Linnaeus in his Systema Naturae of 1758. It was first placed in the genus Papilio. In 1780, Jan Krzysztof Kluk used the Monarch as the type species for a new genus; Danaus. Since Latin grammar requires that the specific epithet and gender names agree it is unclear if the genus Danaus is drawn from Danaus (Greek Δαναός), a mythical king of Egypt and great-grandson of Zeus or is a masculinised version of Danaë (Greek Δανάη), Danaus’s great-great-granddaughter. The species name, plexippus, refers to Plexippus, one of the 50 sons of Aegyptus, Danaus’ twin brother. In Homeric Greek δαναος πληξιππος also means "a Greek who beats (= lashes, drives and urges on) horses", i.e. "Greek charioteer".
The Monarch is closely related to two very similar species which formed the Danaus (Danaus) subgenus before 2005. The first is the Jamaican monarch (D. cleophile) from Jamaica and Hispaniola. The second is the Southern Monarch (D. erippus), of South America south of the Amazon river. The Southern Monarch is almost indistinguishable from the Monarch as an adult, the pupae are somewhat different, and is often considered a subspecies of the Monarch proper. But analysis of morphological, mtDNA 12S rRNA, cytochrome c oxidase subunit I, nuclear DNA 18S rRNA and EF1 subunit α sequence data by Smith et al. (2005) indicates that it is better considered a distinct species. The separation of the Monarch and Southern Monarch is comparatively recent. In all likelihood, the ancestors of the Southern Monarch separated from the Monarch's population some 2 mya, at the end of the Pliocene. At the time sea levels were higher and the entire Amazonas lowland was a vast expanse of brackish swamp that offered hardly any butterfly habitat.
Following the review of Smith et al. (2005), two sub-species of the Monarch are recognized:
Danaus plexippus plexippus, the nominate subspecies, described by Linnaeus in 1758. It is the migratory subspecies known from most of North America.
Danaus plexippus megalippe, named in 1826 by Jacob Hübner. It is the non-migratory subspecies, and is found from Florida and Georgia southwards, throughout the Caribbean and Central America to the Amazon River.
Description
The Monarch’s wingspan ranges from 8.9–10.2 cm (3½–4 in.). The upper side of the wings is tawny-orange, the veins and margins are black, and in the margins are two series of small white spots. The fore wings also have a few orange spots near the tip. The underside is similar but the tip of the fore wing and hind wing are yellow-brown instead of tawny-orange and the white spots are larger.
The male has a black patch of androconial scales responsible for dispersing pheromones on the hind wings, and the black veins on its wing are narrower than the female’s. The male is also slightly larger.
A color variation has been observed in Australia, New Zealand, Indonesia and the United States as early as the late 1800s. Named nivosus by Lepidopterists, it is grayish white in all areas of the wings that are normally orange. Generally it is only about 1% or less of all monarchs, but has maintained populations as high as 10% on Oahu in Hawaii, possibly due to selective predation.
The eggs are creamy white and later turn pale yellow. They are elongate and subconical, with approximately 23 longitudinal ridges and many fine traverse lines. A single egg weighs about 0.46 milligrams (0.0071 gr), and measures about 1.2 millimetres (47 mils) high and 0.9 millimetres (35 mils) wide.
The caterpillar is banded with yellow, black, and white stripes. The head is also striped with yellow and black. There are two pairs of black filaments, one pair on each end of the body. The caterpillar will reach a length of 5 cm (2 in).
The chrysalis is blue-green with a band of black and gold on the end of the abdomen. There are other gold spots on the thorax, the wing bases, and the eyes.
Range and distribution
In North America, the Monarch ranges from southern Canada to northern South America. It rarely strays to western Europe (rarely as far as Greece) from being transported by U. S. ships or by flying there if weather and wind conditions are right. It has also been found in Bermuda, Hawaii, the Solomons, New Caledonia, New Zealand, Australia, New Guinea, Ceylon, India, the Azores, and the Canary Islands.
Migration
Monarchs are especially noted for their lengthy annual migration. In North America they make massive southward migrations starting in August until the first frost. A northward migration takes place in the spring. The monarch is the only butterfly that migrates both north and south as the birds do on a regular basis. But no single individual makes the entire round trip. Female monarchs deposit eggs for the next generation during these migrations.
By the end of October, the population east of the Rocky Mountains migrates to the sanctuaries of the Mariposa Monarca Biosphere Reserve in the Mexican states of Michoacán and México. The western population overwinters in various sites in central coastal and southern California, United States, notably in Pacific Grove and Santa Cruz.
The length of these journeys exceeds the normal lifespan of most monarchs, which is less than two months for butterflies born in early summer. The last generation of the summer enters into a non-reproductive phase known as diapause and may live seven months or more. During diapause, butterflies fly to one of many overwintering sites. The generation that overwinters generally does not reproduce until it leaves the overwintering site sometime in February and March.
It is thought that the overwinter population of those east of the Rockies may reach as far north as Texas and Oklahoma during the spring migration. It is the second, third and fourth generations that return to their northern locations in the United States and Canada in the spring. How the species manages to return to the same overwintering spots over a gap of several generations is still a subject of research; the flight patterns appear to be inherited, based on a combination of the position of the sun in the sky and a time-compensated Sun compass that depends upon a circadian clock that is based in their antennae.
Monarch butterflies are one of the few insects capable of making trans-Atlantic crossings. They are becoming more common in Bermuda due to increased usage of milkweed as an ornamental plant in flower gardens. Monarch butterflies born in Bermuda remain year round due to the island's mild climate. A few monarchs turn up in the far southwest of Great Britain in years when the wind conditions are right, and have been sighted as far east as Long Bennington. In Australia, Monarchs make limited migrations in cooler areas,but the Blue Tiger butterfly is better known in Australia for its lengthy migration. Monarchs can also be found in New Zealand. On the islands of Hawaii no migrations have been noted.
Monarch butterflies are poisonous or distasteful to birds and mammals because of the presence of cardiac glycosides that are contained in milkweed consumed by the larva. It is thought that the bright colors of larva and adults function as warning colors. During hibernation monarch butterflies sometimes suffer losses because hungry birds pick through them looking for the butterflies with the least amount of poison, but in the process killing those that they reject.
Habitat
The Monarch can be found in a wide range of habitats such as fields, meadows, prairie remnants, urban and suburban parks, gardens, and roadsides. It overwinters in conifer groves.
Adult food sources
Adult Monarchs have been seen on a number of different nectar plants. A list of nectar-resources exploited by Monarch butterflies is as follows:
Apocynum cannabinum - Indian Hemp
Asclepias incarnata - Swamp Milkweed
Asclepias syriaca - Common Milkweed
Asclepias tuberosa - Butterfly Weed
Aster sp. - asters
Cirsium sp. - thistles
Daucus carota - Wild Carrot
Dipsacus sylvestris - Teasel
Erigeron canadensis - Horseweed
Eupatorium maculatum - Spotted Joe-Pye Weed
Eupatorium perfoliatum - Common Boneset
Hesperis matronalis - Dame's Rocket
Medicago sativa - Alfalfa
Solidago sp. - golden rods
Syringa vulgaris - Lilac
Trifolium pratense - Red Clover
Vernonia altissima - Tall Ironweed
Males will also take in moisture and minerals from damp soil and wet gravel, a behavior known as puddling. The Monarch has also been noticed puddling at an oil stain on pavement.
Reproduction
The mating period for the overwinter population occurs in the spring, just prior to migration from the overwintering sites. The courtship is fairly simple and less dependent on chemical pheromones in comparison with other species in its genus. Courtship is composed of two distinct stages, the aerial phase and the ground phase. During the aerial phase, the male pursues, nudges, and eventually takes down the female. Copulation occurs during the ground phase where the male and female remain attached for about 30 to 60 minutes. A spermatophore is transferred from the male to the female. Along with sperm, the spermatophore is thought to provide the female with energy resources that aid her in carrying out reproduction and remigration. The overwinter population returns only as far north as they need to go to find the early milkweed growth; in the case of the eastern butterflies that is commonly southern Texas. The life cycle of a monarch includes a change of form called complete metamorphosis. The monarch goes through four radically different stages:
The eggs are laid by the females during spring and summer breeding months.
The eggs hatch (after 4 days), revealing worm-like larvae, the caterpillars. The caterpillars consume their egg cases, then feed on milkweed, and sequester substances called cardenolides, a type of cardiac glycoside.
During the caterpillar stage, monarchs store energy in the form of fat and nutrients to carry them through the non-feeding pupa stage. The caterpillar stage lasts around 2 weeks.
In the pupa or chrysalis stage, the caterpillar spins a silk pad on a twig, leaf, etc., and hangs from this pad by its last pair of prolegs. It hangs upside down in the shape of a 'J', and then molts, leaving itself encased in an articulated green exoskeleton. At this point, hormonal changes occur, leading to the development of a butterfly (metamorphosis). The chrysalis darkens (actually becomes transparent) a day before it emerges, and its orange and black wings can be seen.
The mature butterfly emerges after about two pupal weeks and hangs from the split chrysalis for several hours until its wings are dry (often in the morning). Meanwhile fluids are pumped into the crinkled wings until they become full and stiff. Some of this orangey fluid (called meconium) drips from the wings. Finally (usually in the afternoon) the monarch spreads its wings, quivers them to be sure they are stiff, and then flies away, to feed on a variety of flowers, including milkweed flowers, red clover, and goldenrod.
Monarchs can live a life of two to eight weeks in a garden having their host Asclepias plants and sufficient flowers for nectar. This is especially true if the flower garden happens to be surrounded by native forest that seems to be lacking in flowers.
Host plants
Here is a list of host plants used by the Monarch caterpillar:
Asclepias amplexicaulis - Clasping Milkweed
Asclepias asperula - Antelope Horns
Asclepias californica - California Milkweed
Asclepias cordifolia - Heart-leaf Milkweed
Asclepias curassavica - Scarlet Milkweed
Asclepias curtissii - Curtiss' Milkweed
Asclepias eriocarpa - Woollypod Milkweed
Asclepias erosa - Desert Milkweed
Asclepias exaltata - Poke Milkweed
Asclepias fascicularis - Narrow-leaf Milkweed
Asclepias humistrata - Sandhill Milkweed
Asclepias incarnata - Swamp Milkweed
Asclepias nivea - Caribbean Milkweed
Asclepias physocarpa - Swan Plant
Asclepias purpurascens - Purple Milkweed
Asclepias speciosa - Showy Milkweed
Asclepias subverticillata - Horsetail Milkweed
Asclepias syriaca - Common Milkweed
Asclepias tuberosa - Butterfly Weed
Asclepias verticillata - Whorled Milkweed
Calotropis gigantea - Crown Flower
Calotropis procera - Apple of Sodom
Cynanchum laeva - Sand Vine
Sarcostemma clausa - White Vine
Defense against predators
Monarchs are foul-tasting and poisonous due to the presence of cardenolide aglycones in their bodies, which the caterpillars ingest as they feed on milkweed.
Both forms advertise their unpalatability with bright colors and areas of high contrast on the skin or wings. This phenomenon is known as aposematism.
Monarchs also contain cardiac glycosides in their bodies from the Asclepias plants that the caterpillars eat. Overwintering Monarchs in Mexico are often preyed upon by Black-headed Grosbeaks which are immune to that toxin. Other birds such as orioles and jays have learned to eat only the thoracic muscles and abdominal contents because these contain less poison than the rest of the body.] Some mice are also able to withstand large doses of the poison. Over time, overwintering adults become less poisonous, thus making them more vulnerable to predators. In Mexico, about 14% of the overwintering Monarchs are eaten by birds and mice.
Monarchs share this defense with the similar-appearing viceroy butterfly, in an example of Müllerian mimicry. (Viceroys were at one time believed to be Batesian mimics of monarchs.)
From Carnivora.
carnivora.net/monarch-butterfly-danaus-plexippus-t1210.html
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Superfamily: Papilionoidea
Family: Nymphalidae
Subfamily: Danainae
Tribe: Danaini
Genus: Danaus
Species: Danaus plexippus
The Monarch butterfly (Danaus plexippus) is a milkweed butterfly (subfamily Danainae), in the family Nymphalidae. It is perhaps the best known of all North American butterflies. Since the 19th century, it has been found in New Zealand, and in Australia since 1871 where it is called the Wanderer. In Europe it is resident in the Canary Islands, the Azores, and Madeira, and is found as an occasional migrant in Western Europe. Its wings feature an easily recognizable orange and black pattern, with a wingspan of 8.9–10.2 centimetres (3½–4 in). (The Viceroy butterfly has a similar size, color, and pattern, but can be distinguished by an extra black stripe across the hind wing.) Female Monarchs have darker veins on their wings, and the males have a spot called the "androconium" in the center of each hind wing from which pheromones are released. Males are also slightly larger.
The Monarch is famous for its southward migration and northward return in summer in the Americas which spans the life of three to four generations of the butterfly.
Taxonomy
The common name “Monarch” was first published in 1874 by Samuel H. Scudder because “it is one of the largest of our butterflies, and rules a vast domain”. But the name may be in honour of King William III of England. The Monarch was one of the many species originally described by Linnaeus in his Systema Naturae of 1758. It was first placed in the genus Papilio. In 1780, Jan Krzysztof Kluk used the Monarch as the type species for a new genus; Danaus. Since Latin grammar requires that the specific epithet and gender names agree it is unclear if the genus Danaus is drawn from Danaus (Greek Δαναός), a mythical king of Egypt and great-grandson of Zeus or is a masculinised version of Danaë (Greek Δανάη), Danaus’s great-great-granddaughter. The species name, plexippus, refers to Plexippus, one of the 50 sons of Aegyptus, Danaus’ twin brother. In Homeric Greek δαναος πληξιππος also means "a Greek who beats (= lashes, drives and urges on) horses", i.e. "Greek charioteer".
The Monarch is closely related to two very similar species which formed the Danaus (Danaus) subgenus before 2005. The first is the Jamaican monarch (D. cleophile) from Jamaica and Hispaniola. The second is the Southern Monarch (D. erippus), of South America south of the Amazon river. The Southern Monarch is almost indistinguishable from the Monarch as an adult, the pupae are somewhat different, and is often considered a subspecies of the Monarch proper. But analysis of morphological, mtDNA 12S rRNA, cytochrome c oxidase subunit I, nuclear DNA 18S rRNA and EF1 subunit α sequence data by Smith et al. (2005) indicates that it is better considered a distinct species. The separation of the Monarch and Southern Monarch is comparatively recent. In all likelihood, the ancestors of the Southern Monarch separated from the Monarch's population some 2 mya, at the end of the Pliocene. At the time sea levels were higher and the entire Amazonas lowland was a vast expanse of brackish swamp that offered hardly any butterfly habitat.
Following the review of Smith et al. (2005), two sub-species of the Monarch are recognized:
Danaus plexippus plexippus, the nominate subspecies, described by Linnaeus in 1758. It is the migratory subspecies known from most of North America.
Danaus plexippus megalippe, named in 1826 by Jacob Hübner. It is the non-migratory subspecies, and is found from Florida and Georgia southwards, throughout the Caribbean and Central America to the Amazon River.
Description
The Monarch’s wingspan ranges from 8.9–10.2 cm (3½–4 in.). The upper side of the wings is tawny-orange, the veins and margins are black, and in the margins are two series of small white spots. The fore wings also have a few orange spots near the tip. The underside is similar but the tip of the fore wing and hind wing are yellow-brown instead of tawny-orange and the white spots are larger.
The male has a black patch of androconial scales responsible for dispersing pheromones on the hind wings, and the black veins on its wing are narrower than the female’s. The male is also slightly larger.
A color variation has been observed in Australia, New Zealand, Indonesia and the United States as early as the late 1800s. Named nivosus by Lepidopterists, it is grayish white in all areas of the wings that are normally orange. Generally it is only about 1% or less of all monarchs, but has maintained populations as high as 10% on Oahu in Hawaii, possibly due to selective predation.
The eggs are creamy white and later turn pale yellow. They are elongate and subconical, with approximately 23 longitudinal ridges and many fine traverse lines. A single egg weighs about 0.46 milligrams (0.0071 gr), and measures about 1.2 millimetres (47 mils) high and 0.9 millimetres (35 mils) wide.
The caterpillar is banded with yellow, black, and white stripes. The head is also striped with yellow and black. There are two pairs of black filaments, one pair on each end of the body. The caterpillar will reach a length of 5 cm (2 in).
The chrysalis is blue-green with a band of black and gold on the end of the abdomen. There are other gold spots on the thorax, the wing bases, and the eyes.
Range and distribution
In North America, the Monarch ranges from southern Canada to northern South America. It rarely strays to western Europe (rarely as far as Greece) from being transported by U. S. ships or by flying there if weather and wind conditions are right. It has also been found in Bermuda, Hawaii, the Solomons, New Caledonia, New Zealand, Australia, New Guinea, Ceylon, India, the Azores, and the Canary Islands.
Migration
Monarchs are especially noted for their lengthy annual migration. In North America they make massive southward migrations starting in August until the first frost. A northward migration takes place in the spring. The monarch is the only butterfly that migrates both north and south as the birds do on a regular basis. But no single individual makes the entire round trip. Female monarchs deposit eggs for the next generation during these migrations.
By the end of October, the population east of the Rocky Mountains migrates to the sanctuaries of the Mariposa Monarca Biosphere Reserve in the Mexican states of Michoacán and México. The western population overwinters in various sites in central coastal and southern California, United States, notably in Pacific Grove and Santa Cruz.
The length of these journeys exceeds the normal lifespan of most monarchs, which is less than two months for butterflies born in early summer. The last generation of the summer enters into a non-reproductive phase known as diapause and may live seven months or more. During diapause, butterflies fly to one of many overwintering sites. The generation that overwinters generally does not reproduce until it leaves the overwintering site sometime in February and March.
It is thought that the overwinter population of those east of the Rockies may reach as far north as Texas and Oklahoma during the spring migration. It is the second, third and fourth generations that return to their northern locations in the United States and Canada in the spring. How the species manages to return to the same overwintering spots over a gap of several generations is still a subject of research; the flight patterns appear to be inherited, based on a combination of the position of the sun in the sky and a time-compensated Sun compass that depends upon a circadian clock that is based in their antennae.
Monarch butterflies are one of the few insects capable of making trans-Atlantic crossings. They are becoming more common in Bermuda due to increased usage of milkweed as an ornamental plant in flower gardens. Monarch butterflies born in Bermuda remain year round due to the island's mild climate. A few monarchs turn up in the far southwest of Great Britain in years when the wind conditions are right, and have been sighted as far east as Long Bennington. In Australia, Monarchs make limited migrations in cooler areas,but the Blue Tiger butterfly is better known in Australia for its lengthy migration. Monarchs can also be found in New Zealand. On the islands of Hawaii no migrations have been noted.
Monarch butterflies are poisonous or distasteful to birds and mammals because of the presence of cardiac glycosides that are contained in milkweed consumed by the larva. It is thought that the bright colors of larva and adults function as warning colors. During hibernation monarch butterflies sometimes suffer losses because hungry birds pick through them looking for the butterflies with the least amount of poison, but in the process killing those that they reject.
Habitat
The Monarch can be found in a wide range of habitats such as fields, meadows, prairie remnants, urban and suburban parks, gardens, and roadsides. It overwinters in conifer groves.
Adult food sources
Adult Monarchs have been seen on a number of different nectar plants. A list of nectar-resources exploited by Monarch butterflies is as follows:
Apocynum cannabinum - Indian Hemp
Asclepias incarnata - Swamp Milkweed
Asclepias syriaca - Common Milkweed
Asclepias tuberosa - Butterfly Weed
Aster sp. - asters
Cirsium sp. - thistles
Daucus carota - Wild Carrot
Dipsacus sylvestris - Teasel
Erigeron canadensis - Horseweed
Eupatorium maculatum - Spotted Joe-Pye Weed
Eupatorium perfoliatum - Common Boneset
Hesperis matronalis - Dame's Rocket
Medicago sativa - Alfalfa
Solidago sp. - golden rods
Syringa vulgaris - Lilac
Trifolium pratense - Red Clover
Vernonia altissima - Tall Ironweed
Males will also take in moisture and minerals from damp soil and wet gravel, a behavior known as puddling. The Monarch has also been noticed puddling at an oil stain on pavement.
Reproduction
The mating period for the overwinter population occurs in the spring, just prior to migration from the overwintering sites. The courtship is fairly simple and less dependent on chemical pheromones in comparison with other species in its genus. Courtship is composed of two distinct stages, the aerial phase and the ground phase. During the aerial phase, the male pursues, nudges, and eventually takes down the female. Copulation occurs during the ground phase where the male and female remain attached for about 30 to 60 minutes. A spermatophore is transferred from the male to the female. Along with sperm, the spermatophore is thought to provide the female with energy resources that aid her in carrying out reproduction and remigration. The overwinter population returns only as far north as they need to go to find the early milkweed growth; in the case of the eastern butterflies that is commonly southern Texas. The life cycle of a monarch includes a change of form called complete metamorphosis. The monarch goes through four radically different stages:
The eggs are laid by the females during spring and summer breeding months.
The eggs hatch (after 4 days), revealing worm-like larvae, the caterpillars. The caterpillars consume their egg cases, then feed on milkweed, and sequester substances called cardenolides, a type of cardiac glycoside.
During the caterpillar stage, monarchs store energy in the form of fat and nutrients to carry them through the non-feeding pupa stage. The caterpillar stage lasts around 2 weeks.
In the pupa or chrysalis stage, the caterpillar spins a silk pad on a twig, leaf, etc., and hangs from this pad by its last pair of prolegs. It hangs upside down in the shape of a 'J', and then molts, leaving itself encased in an articulated green exoskeleton. At this point, hormonal changes occur, leading to the development of a butterfly (metamorphosis). The chrysalis darkens (actually becomes transparent) a day before it emerges, and its orange and black wings can be seen.
The mature butterfly emerges after about two pupal weeks and hangs from the split chrysalis for several hours until its wings are dry (often in the morning). Meanwhile fluids are pumped into the crinkled wings until they become full and stiff. Some of this orangey fluid (called meconium) drips from the wings. Finally (usually in the afternoon) the monarch spreads its wings, quivers them to be sure they are stiff, and then flies away, to feed on a variety of flowers, including milkweed flowers, red clover, and goldenrod.
Monarchs can live a life of two to eight weeks in a garden having their host Asclepias plants and sufficient flowers for nectar. This is especially true if the flower garden happens to be surrounded by native forest that seems to be lacking in flowers.
Host plants
Here is a list of host plants used by the Monarch caterpillar:
Asclepias amplexicaulis - Clasping Milkweed
Asclepias asperula - Antelope Horns
Asclepias californica - California Milkweed
Asclepias cordifolia - Heart-leaf Milkweed
Asclepias curassavica - Scarlet Milkweed
Asclepias curtissii - Curtiss' Milkweed
Asclepias eriocarpa - Woollypod Milkweed
Asclepias erosa - Desert Milkweed
Asclepias exaltata - Poke Milkweed
Asclepias fascicularis - Narrow-leaf Milkweed
Asclepias humistrata - Sandhill Milkweed
Asclepias incarnata - Swamp Milkweed
Asclepias nivea - Caribbean Milkweed
Asclepias physocarpa - Swan Plant
Asclepias purpurascens - Purple Milkweed
Asclepias speciosa - Showy Milkweed
Asclepias subverticillata - Horsetail Milkweed
Asclepias syriaca - Common Milkweed
Asclepias tuberosa - Butterfly Weed
Asclepias verticillata - Whorled Milkweed
Calotropis gigantea - Crown Flower
Calotropis procera - Apple of Sodom
Cynanchum laeva - Sand Vine
Sarcostemma clausa - White Vine
Defense against predators
Monarchs are foul-tasting and poisonous due to the presence of cardenolide aglycones in their bodies, which the caterpillars ingest as they feed on milkweed.
Both forms advertise their unpalatability with bright colors and areas of high contrast on the skin or wings. This phenomenon is known as aposematism.
Monarchs also contain cardiac glycosides in their bodies from the Asclepias plants that the caterpillars eat. Overwintering Monarchs in Mexico are often preyed upon by Black-headed Grosbeaks which are immune to that toxin. Other birds such as orioles and jays have learned to eat only the thoracic muscles and abdominal contents because these contain less poison than the rest of the body.] Some mice are also able to withstand large doses of the poison. Over time, overwintering adults become less poisonous, thus making them more vulnerable to predators. In Mexico, about 14% of the overwintering Monarchs are eaten by birds and mice.
Monarchs share this defense with the similar-appearing viceroy butterfly, in an example of Müllerian mimicry. (Viceroys were at one time believed to be Batesian mimics of monarchs.)
From Carnivora.
carnivora.net/monarch-butterfly-danaus-plexippus-t1210.html