Claudio Contreras / Monarch butterfly (Danaus plexippus) hibernating, Mariposa Monarca Special Biosphere Reserve, central Mexico, January.

Claudio Contreras / Monarch butterfly (Danaus plexippus) hibernating, Mariposa Monarca Special Biosphere Reserve, central Mexico, January.

Floris van Breugel / Monarch Butterflies (Danaus plexippus) roosting in winter in dense groups, Southern California, USA

Stephen Dalton / Monarch butterfly (Danaus plexippus) female in flight. Did you know? Monarch buttterflies migrate up to 2500 miles from Mexico to Canada.

Inaki Relanzon / Clouds of Monarch butterflies {Danaus plexippus} flying and resting on trees while on migration, Miochacan, Mexico, January 1997

Jack Dykinga / Monarch Butterflies (Danaus plexippus) covering the trunk of a coniferous tree, Sierra Chincua Monarch Butterfly Biosphere Reserve, Michoacan, Mexico, Central America

Rolf Nussbaumer / Monarch butterfly just emerged from chrysalis {Danaus plexippus} Texas, USA.

Claudio Contreras / Monarch butterfly (Danaus plexippus) hibernating in Sacred Fir (Abies religiosa) forest, Mariposa Monarca Special Biosphere Reserve, central Mexico, January.

Claudio Contreras / Monarch butterfly (Danaus plexippus) hibernating, Mariposa Monarca Special Biosphere Reserve, central Mexico, January.

LYNN M. STONE / Monarch Butterfly (Danaus plexippus) on Zinnia flower. Geneva, Illinois, USA, September.

MYN / Paul Marcellini / Caterpillar larva of the Monarch butterfly (Danaus plexippus) Florida, USA, March. meetyourneighbours.net project

MYN / Paul Marcellini / Caterpillar larva of the Monarch butterfly (Danaus plexippus) feeding on leaf, Florida, USA, March. meetyourneighbours.net project

MYN / Paul Marcellini / Caterpillar larva of the Monarch butterfly (Danaus plexippus) Florida, USA, March. meetyourneighbours.net project

LYNN M. STONE / Monarch butterfly (Danaus plexippus) feeding on Joe-Pye weed (Eupatoriadelphus dubius) flowers, North Guilford, Connecticut, USA, August

LYNN M. STONE / Monarch butterfly (Danaus plexippus) feeding on Butterfly weed (Asclepias tuberosa) flowers, Old Saybrook, Connecticut, USA, August

LYNN M. STONE / Monarch butterfly (Danaus plexippus) feeding on Butterfly weed (Asclepias tuberosa) flowers, Old Saybrook, Connecticut, USA, August

Marie Read / Monarch butterfly (Danaus plexippus) feeding on New England aster (Aster novae-angliae), New York, USA, October

LYNN M. STONE / Monarch butterflies (Danaus plexippus) mating on Eastern Joe-Pye-Weed plant (Upatoriadelphus dubius), Connecticut, USA

LYNN M. STONE / Monarch Butterfly (Danaus plexippus), showing some wear and tear on wing, feeding on nectar of Rough Blazing-Star (Liatris aspera) growing in tallgrass prairie remnant, Downers Grove, Illinois, USA

Michele Westmorland / Frangipani hornworm / hawk moth (Pseudosphinx tetrio) on flowering foliage, Tobago, Caribbean.

Michele Westmorland / Frangipani hornworm / hawkmoth caterpillar (Pseudosphinx tetrio) on flowering foliage, Tobago, Caribbean.

Michele Westmorland / Frangipani hornworm / hawkmoth caterpillar (Pseudosphinx tetrio) , Tobago, Caribbean.

Neil Lucas / Monarch butterfly (Danaus plexippus) at rest with wings open on wildflower stem, Prairie, USA

Neil Lucas / Monarch butterfly (Danaus plexipps) collecting nectar from flowers, Prairie, Minnesota, USA,

Neil Lucas / Monarch butterfly (Danus plexippus) at rest on a flower stem, Prairie, USA

Stephen Dalton / Monarch butterfly (Danaus plexippus) in flight, controlled conditions

Stephen Dalton / Monarch butterfly (Danaus plexippus) adult emerging from pupal case, controlled conditions

John Cancalosi / European Praying Mantid (Mantis religiosa) feeding on Monarch Butterfly (Danaus plexippus) New York, USA

John Cancalosi / European Praying Mantid (Mantis religiosa) feeding on Monarch Butterfly (Danaus plexippus) New York, USA

Stephen Dalton / Monarch butterfly (Danaus plexippus) in flight

Doug Wechsler / Tagging and measuring a Monarch Butterfly (Danaus plexippus) for reseach, New Jersey, Cape May, USA

Doug Wechsler / Tagging a Monarch Butterfly (Danaus plexippus) for research, New Jersey, Cape May, USA

Doug Wechsler / Monarch Butterfly caterpillar (Danas plexippus) feeding on Butterflyweed (Ascelepias tuberosa), Pennsylvania, USA

Doug Wechsler / Monarch Butterfly caterpillar (Danas plexippus) feeding on Butterflyweed (Ascelepias tuberosa), Pennsylvania, USA

Doug Wechsler / Caterpillar larva of Monarch butterfly {Danaus plexippus} on leaves of host plant Common milkweed (Asclepias syriaca) Adirondack Park, New York, USA

Stephen Dalton / Monarch butterfly {Danaus plexippus} flight sequence, multiflash image

Andrew Walmsley / Monarch butterfly (Danaus plexippus) on flowers, Christchurch, New Zealand, May

Claudio Contreras / Hibernating Monarch butterflies (Danaus plexippus) El Rosario Colony, Monarch Butterfly Sanctuary, Mexico, February

Claudio Contreras / Hibernating Monarch butterflies (Danaus plexippus) on Oyamel fir trees (Abies religiosa), El Zacatal Colony, Monarch Butterfly Sanctuary, Mexico, December 1996

Claudio Contreras / Hibernating Monarch butterflies (Danaus plexippus) El Zacatal Colony, Monarch Butterfly Sanctuary, Mexico, December 1996

Claudio Contreras / Colony of Monarch butterflies (Danaus plexippus) hibernating on Oyamel fir trees (Abies religiosa) El Zacatal Colony, Monarch Butterfly Sanctuary, Mexico, December 1996

Jerry Monkman / Monarch butterfly {Danaus plexippus} on clover, Massachusetts, USA

Thomas Lazar / Monarch butterfly (Danaus plexippus) butterfly newly emerged from chrysalis, drying wings, Wisconsin, USA. Sequence 9/9.

Thomas Lazar / Monarch butterfly (Danaus plexippus) chrysalis with pre-emergent butterfly visible inside, Wisconsin, USA. Sequence 1/9.

Thomas Lazar / Monarch butterfly (Danaus plexippus) newly emerged, on Purple cone flower {Echinacea purputea} drying wings in the sun, Wisconsin, USA

Thomas Lazar / Monarch butterfly (Danaus plexippus) butterfly emerging from chrysalis, Wisconsin, USA. Sequence 3/9.

Thomas Lazar / Monarch butterfly (Danaus plexippus) butterfly emerging from chrysalis, wings folded, Wisconsin, USA. Sequence 4/9.

Thomas Lazar / Monarch butterfly (Danaus plexippus) butterfly emerging from chrysalis, wings unfolding, Wisconsin, USA. Sequence 6/9.

Thomas Lazar / Monarch butterfly (Danaus plexippus) newly emerged, on Purple cone flower {Echinacea purputea} drying wings in the sun, Wisconsin, USA

Thomas Lazar / Monarch butterfly (Danaus plexippus) butterfly emerging from chrysalis, Wisconsin, USA. Sequence 2/9.

Thomas Lazar / Monarch butterfly (Danaus plexippus) butterfly emerging from chrysalis, wings unfolding, Wisconsin, USA. Sequence 7/9.

Thomas Lazar / Monarch butterfly (Danaus plexippus) caterpillar on Milkweed stalk {Asclepias syriaca}, Wisconsin, USA.

Thomas Lazar / Monarch butterfly (Danaus plexippus) butterfly newly emerged from chrysalis, wings almost completely unfolded, Wisconsin, USA. Sequence 8/9.

Thomas Lazar / Monarch butterfly (Danaus plexippus) caterpillar feeding on Milkweed leaf {Asclepias syriaca}, Wisconsin, USA.

Thomas Lazar / Monarch butterfly (Danaus plexippus) butterfly emerging from chrysalis, wings unfolding, Wisconsin, USA. Sequence 5/9.

Inaki Relanzon / Clouds of Monarch butterflies {Danaus plexippus} flying and resting on trees while on migration, Miochacan, Mexico, January 1997

Jouan & Rius / Monarch butterfly (Danaus plexippus) on leaf, Costa Rica

Ingo Arndt / Milkweed (Asclepias sp) flowers, exclusive food for Monarch Butterfly (Danaus plexippus) larvae, Cape May, New Jersey

Norbert Wu / Monarch (Danaus plexippus) butterfly gathering on eucalyptus trees in winter, Pacific Grove, California

LYNN M. STONE / Monarch butterfly {Dadaus plexippus} in early dew in a field of purple flowers on the Prairies, USA

Tom Vezo / Monarch butterflies on bush {Danaus plexippus} NY, USA

Jack Dykinga / Monarch Butterflies (Danaus plexippus) covering the trunk of a tree in coniferous forest, Sierra Chincua Monarch Butterfly Biosphere Reserve, Michoacan, Mexico, Central America

Jack Dykinga / Monarch Butterflies (Danaus plexippus) flying and landing on trees beneath a coniferous forest, Sierra Chincua Monarch Butterfly Biosphere Reserve, Michoacan, Mexico, Central America

Jack Dykinga / Monarch Butterflies (Danaus plexippus) covering the trunk of a tree in coniferous forest, Sierra Chincua Monarch Butterfly Biosphere Reserve, Michoacan, Mexico, Central America

Jack Dykinga / Monarch Butterflies (Danaus plexippus) clustering on trees in a coniferous forest, Sierra Chincua Monarch Butterfly Biosphere Reserve, Michoacan, Mexico, Central America

Jack Dykinga / Monarch Butterflies (Danaus plexippus) on a tree trunk in coniferous forest, Sierra Chincua Monarch Butterfly Biosphere Reserve, Michoacan, Mexico, Central America

Jack Dykinga / Monarch Butterflies (Danaus plexippus) in the trees of a coniferous forest, Sierra Chincua Monarch Butterfly Biosphere Reserve, Michoacan, Mexico, Central America

Jack Dykinga / Dead Monarch Butterflies (Danaus plexippus) lying on the ground, killed by a January freeze. Sierra Chincua Monarch Butterfly Biosphere Reserve, Michoacan, Mexico, Central America

Jack Dykinga / Monarch Butterflies (Danaus plexippus) flying and landing on plants beneath a coniferous forest, Sierra Chincua Monarch Butterfly Biosphere Reserve, Michoacan, Mexico, Central America

Jose B. Ruiz / Monarch butterfly {Danaus plexippus} on twig, Spain

Jose B. Ruiz / Monarch butterfly {Danaus plexippus} on twig, Spain

Steven David Miller / Monarch butterfly {Danaus plexippus} on leaf, Australia

Doug Wechsler / Monarch butterflies {Danaus plexippus} mating, Pennsylvania, USA

LYNN M. STONE / Chrysalis of Monarch butterfly (Danaus plexippus), USA

Doug Wechsler / Chrysalis of Monarch butterfly (Danaus plexippus) USA

Rod Williams / Monarch butterfly {Danaus plexippus} captive, from North America

Peter Scoones / Monarch butterfly portrait (Danaus plexippus) New Mexico, USA

Philippe Clement / Reddish brown / Monarch butterfly {Danaus plexippus} on leaf, Costa Rica.

Larry Michael / Monarch butterfly {Danaus plexippus} on Mullen plant, USA

Jose B. Ruiz / Monarch butterfly {Danaus plexippus} Alicante, Spain

Doug Wechsler / Monarch butterfly caterpillar (Danaus plexippus)

Adrian Davies / Sign for Monarch butterfly roosting sanctuary during migration, California, USA.

Adrian Davies / Sign warning of Monarch butterfly migration / roosing site, California, USA.

Steven David Miller / Monarch butterfly {Danaus plexippus} resting on flower. USA.

Larry Michael / Monarch butterfly caterpillar on milkweed {Danaus plexippus} Wisconsin USA.

Hans Christoph Kappel / Mass of Monarch butterflies flying near roost trees, wintering in Mexico.

Hans Christoph Kappel / Mass of Monarch butterflies {Danaus plexippus} flying, Mexico.

Hans Christoph Kappel / Monarch butterflies roosting {Danaus plexippus}, Mexico.

Doug Wechsler / Monarch butterflies feeding on Ivy, New Jersey, USA. On southbound migration.

TOM MANGELSEN / Monarch butterflies gathered on on tree trunk (Danaus plexippus) Mexico

Michael Durham / Monarch butterfly chrysalis {Danaus Plexippus} Sequence 1 of 11

Michael Durham / Monarch butterfly chrysalis {Danaus plexippus}. The chrysalis darkens just before adult hatches Sequence 2 of 11

Michael Durham / Monarch butterfly {Danaus plexippus} adult has just broken the skin of the chrysalis and is about to emerge Sequence 3 of 11 .

Michael Durham / Monarch butterfly {Danaus plexippus} adult's wing can just be seen unfolding out of the chrysalis. Sequence 4 of 11

Michael Durham / Monarch butterfly {Danaus plexippus} adult emerging from chrysalis casing. Sequence 5 of 11