Danaus plexippus (DAN-ee-us PLEK-see-puss)

Monarch - imago - Thatcham - 25-Sep-06 (0759) [REARED]
Photo © Pete Eeles

95 - 100mm

Checklist Number

Family:NymphalidaeSwainson, 1827
Subfamily:DanainaeBoisduval, 1833
Tribe:DanainiBoisduval, 1833
Genus:DanausKluk, 1780
Species:plexippus(Linnaeus, 1758)

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This species is the largest butterfly seen in the British Isles, and is also one of our rarest migrants. This butterfly is known for its ability to migrate across large distances. The migrations in north America are one of the greatest natural phenomena in the world - where the adult butterflies can migrate from as far north as Canada to the overwintering grounds in very specific sites in Mexico, the west coast of California and Florida. The first record of this species in the British Isles, by a schoolboy, was on 6th September 1876 in Neath in south Wales. Although initial records were thought to be the result of accidental transportation by ship, subsequent years, such as 1933 when 40 individuals were caught, meant that this theory was dismissed and that the most-likely cause was a genuine immigration.

The total number of records for the British Isles is less than 500. The most-recent major migration was in 1981 with 135 sightings. Many north American bird species were also recorded that year. However, there is still some question as to the true origin of this immigration since the species is also known from Madeira, southern Spain, Portugal and the Canary Islands, which it reached in 1860 and survives using Asclepias curassavica as its foodplant.

The larva feeds on various Milkweeds (Asclepias species) which are not native to the British Isles, and this explains why the immature stages have not been found in the British Isles. However, in August 1981, a Monarch that had escaped from a nearby butterfly farm was seen to lay on Milkweeds in Kew Gardens. Some of the eggs were collected and reared indoors, where the first adult emerged just one month after the egg had been laid. This species is a rare migrant to the British Isles. Although there are records from many areas, sightings are concentrated in the south and west of both England and Ireland. There is a particular concentration in Cornwall and the Scilly Isles.

Danaus plexippus

This species was first defined in Linnaeus (1758) as shown here (type locality: North America).

Monarch - imago - Thatcham - 25-Sep-06 (0759) [REARED]

Photo © Pete Eeles

Monarch - imago - Thatcham - 25-Sep-06 (0753) [REARED]

Male Underside
Photo © Pete Eeles

Monarch - imago - Thatcham - 30-Sep-06 (0783) [REARED]

Photo © Pete Eeles

Monarch - imago - Thatcham - 25-Sep-06 (0758) [REARED]

Female Underside
Photo © Pete Eeles

Photo Album ...

Conservation Status

No conservation action is relevant for this species.


Description to be completed.


1.2 Rare Migrant

This species is a rare migrant to the British Isles.

Life Cycle

Although sightings have been recorded from March to November in the British Isles, the peak is in September and October. These latter months correlate with the southward migration in north America and it is not unreasonable to believe that favourable winds have pushed some individuals across the Atlantic. Unfortunately, this spectacular insect is unable to survive our winter.


The male butterfly is distinguished from the female by having less prominent black markings to the veins and conspicuous sex brands on the upperside of the hindwings.

Description of nectar sources to be completed.

Photo Album ...


Eggs are laid singly on the foodplant and this stage lasts only 3 or 4 days.

Monarch - ovum - Dominican Republic - 18-Aug-05

Photo © Pete Eeles

Monarch - ovum - Unknown location - Unknown date [REARED] [Brian Clegg]

Photo © Brian Clegg

Monarch - ovum2 [William Zittrich]

Photo © William Zittrich

Monarch - ovum [William Zittrich]

Photo © William Zittrich

Photo Album ...


The larva eats its eggshell on hatching before feeding on the leaves of the foodplant. The larvae are conspicuously marked, providing a warning to predators that the larva is poisonous, having built up toxins that it obtains from the foodplant. These poisons are passed on to the adult butterfly. Depending on temperature, this stage can be completed in as little as 16 days.

The primary larval foodplant is Milkweeds (various) (Asclepias spp.).

Monarch - larva3 [William Zittrich]

Photo © William Zittrich

Monarch - larva - Stratford-upon-Avon - 13-Jun-10 (2) {REARED}

Photo © Pete Eeles

Monarch - larva - Unknown location - Unknown date (2) [Brian Clegg]

Photo © Brian Clegg

Monarch - larva - Stratford-upon-Avon - 13-Jun-10 (1) {REARED}

Photo © Pete Eeles

Photo Album ...


The pupa hangs head-down from a stem or leaf, attached by its cremaster. This stage lasts around 2 weeks.

Monarch - pupa [William Zittrich]

Photo © William Zittrich

Monarch - pupa - Thatcham - 06-Oct-04 [REARED]

Photo © Pete Eeles

Monarch - pupa - Thatcham - 25-Sep-06 (0748) [REARED]

Photo © Pete Eeles

Monarch - pupa - Thatcham - 23-Jul-14 [REARED]

Photo © Pete Eeles

Photo Album ...


Description to be completed.

Click here to see the aberration descriptions and images for this species.

Similar Species

No similar species found.


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The following links provide additional information on this butterfly.


The species description provided here references the following publications:

Boisduval (1833) Boisduval, J.A. (1833) Icones historiques des Lépidoptères d'Europe nouveaux.
Kluk (1780) Kluk, K. (1780) Zwierzat domowych i dzikich osobliwie kraiowych historyi naturalney poczatki i gospodarstwo.
Linnaeus (1758) Linnaeus, C. (1758) Systema Naturae. Edition 10.
Swainson (1827) Swainson, W. (1827) A Sketch of the Natural Affinities of the Lepidoptera Diurna of Latreille. The Philosophical magazine : or Annals of chemistry, mathematics, astronomy, natural history and general science.