T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Monarch butterfly (Danaus plexippus)

Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Superfamily: Papilionoidea
Family: Nymphalidae
Subfamily: Danainae
Tribe: Danaini
Genus: Danaus
Species: D. plexippus
Scientific name: Danaus plexippus
Common name: Monarch Butterfly

The monarch arrived in New Zealand about 120 years` ago crossing the Pacific from North America. It is New Zealand's largest resident butterfly. 
Its caterpillar's food is the Swan plant (Asclepias physocarpa). Their live cycle is two weeks as a caterpillar, two weeks as a chrysalis and about two months as a butterfly. 
Female Monarchs have darker veins on their wings, and the males have a spot in the centre of each hindwing from which pheromones are released. Males are also slightly larger.

For information on pheromones visit http://en.wikipedia.org/wiki/Pheromones

A butterfly at rest. 

Danaus plexippus female (male photo below)

Danaus plexippus male. Notice the pheromone releasing spot on each hind wing.

Danaus plexippus (female)

Danaus plexippus (female)

Sunlight shining through Danaus plexippus partly translucent wings.

A male butterfly of a swan plant the favourite food of the caterpillar.

Danaus plexippus head ( female)
Butterflies mating.

A monarch butterfly caterpillar

The caterpillar has just attached itself to a branch in preparation for forming a chrysalis

Next stage, forming a chrysalis.

The monarch butterfly chrysalis
The monarch butterfly chrysalis with the developing butterfly's wing patterns just visible.

A video: How A Caterpillar Becomes A Butterfly 

Thanks to Wikipedia for text and information http://creativecommons.org/licenses/by-sa/3.0/