Sylvain Cordier / Monarch butterfly (Danaus plexippus) wintering in Oyamel pine forests (Abies religiosa) Monarch Butterfly Biosphere Reserve / Reserva de Biosfera de la Mariposa Monarca UNESCO World Heritage Site, An...

Sylvain Cordier / Monarch butterfly (Danaus plexippus), wintering from November to March in Oyamel pine forests (Abies religiosa) Monarch Butterfly Biosphere Reserve, Mexico.

Ingo Arndt / Monarch butterflies (Danaus plexippus) gathered to drink, overwintering colony, Michoacan, Mexico

Ingo Arndt / Cloud of Monarch butterflies (Danaus plexippus) flying, overwintering colony, Michoacan, Mexico

Ingo Arndt / Monarch butterflies (Danaus plexippus) flying amongst trees, overwintering colony, Michoacan, Mexico

Ingo Arndt / Monarch butterfly (Danaus plexippus) hanging from a blade of grass, silhouetted against the full moon, East coast USA.

Ingo Arndt / Monarch butterflies (Danaus plexippus) flying in warmth of midday sun, overwintering colony in Michoacan, Mexico

Ingo Arndt / Monarch butterflies (Danaus plexippus) drinking from pool of water, overwintering colony, Michoacan, Mexico

Ingo Arndt / Male Monarch butterfly (Danaus plexippus) feeding on nectar of Goldenrod flowers, East coast, USA

Floris van Breugel / Monarch butterflies (Danaus plexippus) over winter on Eucalyptus and Monterey Cypress trees near Pismo Beach, San Luis, California, USA December.. When temperatures warm up enough, they will embark on...

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

Ingo Arndt / Monarch (Danaus plexippus) butterfly feeding on nectar of Goldenrod during migration, East Coast, USA

Ingo Arndt / Monarch (Danaus plexippus) butterflies gathering to drink water and take up minerals, Michoacan, Mexico

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

Patricio Robles Gil / Monarch (Danaus plexippus) butterfly, mass flying in wintering grounds, Monarch butterfly Biosphere Reserve, Michoacan, Mexico

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

Michael & Patricia Fogden / Monarch (Danaus plexippus) butterfly, feeding on Scarlet Milkweed (Asclepias curassavica) in the cloud forest, Costa Rica

Thomas Mangelsen / Monarch (Danaus plexippus) butterfly group perching on a female tourist, El Rosario Monarch Butterfly Sanctuary, Mexico

Jim Brandenburg / Monarch (Danaus plexippus) butterfly group resting on Giant Sunflower (Helianthus giganteus) during migration, Iowa

Jim Brandenburg / Monarch (Danaus plexippus) butterfly newly emerged from chrysalis, California

Jim Brandenburg / Monarch (Danaus plexippus) butterfly group resting on Thickspike Gayfeather (Liatris pycnostachya) flowers, North America

Jim Brandenburg / Monarch (Danaus plexippus) butterfly emerging from cocoon, Minnesota

Jim Brandenburg / Monarch (Danaus plexippus) butterfly, Minnesota

Tim Fitzharris / Monarch (Danaus plexippus) butterflies on lupine, Michoacan, Mexico

Heather Angel / Monarch butterflies (Danaus plexippus), three nectaring on Poinsettia (Euphorbia pulcherrima), resting on red bracts. In butterfly house, Xishuangbanna, Yunnan Province, China.

Doc White / Monarch butterfly, (Danaus plexippus), migrating group resting in tree Pismo Beach, California, USA. January.

Doc White / Monarch butterfly, (Danaus plexippus), migrating group resting in tree Pismo Beach, California, USA. January.

Doc White / Monarch butterfly, (Danaus plexippus), migrating group resting in tree Pismo Beach, California, USA. January.

Doc White / Monarch butterfly, (Danaus plexippus), migrating group resting in tree Pismo Beach, California, USA. January.

Derek Galon / Caterpillar of Monarch butterfly (Danaus plexippus) feeding on seed pod of Bloodflower plant ( Asclepias curassavica). Dominica, Eastern Caribbean, Lesser Antilles. Focus stacked photo.

Paul Williams / Nephila pilipes spider and common tiger butterfly (Danaus genutia). The butterfly contains toxins that make it distateful to the spider, so the spider snips the butterfly out of its web and releases i...

MYN / Lily Kumpe / Lesser wanderer butterfly (Danaus petilia) William Bay National Park, Western Australia. Meetyourneighbours.net project.

Nick Hawkins / Monarch butterfly (Danaus plexippus) male, migrating North, Anchorage Provincial Park, Grand Manan Island, New Brunswick, Canada, June.

Doug Wechsler / Monarch butterfly ( Danaus plexippus) egg on common milkweed; Philadelphia, Pennsylvania, USA. August.

Lynn M. Stone / Tagged Monarch butterfly (Danaus plexippus) on Dahlia flower, October. Waterford, Connecticut, USA (non-ex)

Jaymi Heimbuch / Monarch (Danaus plexippus) group wintering, Pismo Beach, California

Hanne & Jens Eriksen / Plain tiger butterfly (Danaus chrysippus) September, Oman

Ingo Arndt / Monarch butterfly (Danaus plexippus) emerging from its pupa, USA, Sequence 8/8

Ingo Arndt / Monarch butterfly (Danaus plexippus) emerging from its pupa, USA, Sequence 7/8

Ingo Arndt / Monarch butterfly (Danaus plexippus) emerging from its pupa, USA, Sequence 4/8

Ingo Arndt / Monarch butterfly (Danaus plexippus) emerging from its pupa, USA, Sequence 3/8

Ingo Arndt / Monarch butterfly (Danaus plexippus) emerging from its pupa, USA, Sequence 2/8

Ingo Arndt / Monarch butterfly (Danaus plexippus) emerging from its pupa, USA, Sequence 1/8

Ingo Arndt / Monarch butterfly (Danaus plexippus) emerging from its pupa, USA, Sequence 6/8

Ingo Arndt / Monarch butterfly (Danaus plexippus) emerging from its pupa, USA, Sequence 5/8

Ingo Arndt / Cloud of Monarch butterflies (Danaus plexippus) flying, overwintering colony, Michoacan, Mexico

Ingo Arndt / Dead Monarch butterflies (Danaus plexippus) on the ground killed by changing weather conditions bringing wet and cold weather, Michoacan, Mexico

Ingo Arndt / Caterpillar larva of Monarch butterfly (Danaus plexippus) on Milkweed leaf (Asclepias sp), USA

Ingo Arndt / Close-up of wing pattern on Monarch butterfly (Danaus plexippus) USA

Ingo Arndt / Monarch butterflies (Danaus plexippus) covering tree trunk, early morning, overwintering colony, Michoacan, Mexico

Ingo Arndt / Monarch butterflies (Danaus plexippus) mating, Michoacan, Mexico. Females lay their eggs on their journey north.

Ingo Arndt / Egg of Monarch butterfly (Danaus plexippus) on the underside of Milkweed leaf (Asclepias spec) USA

Ingo Arndt / Mass of Monarch butterflies (Danaus plexippus) flying, overwintering colony, Michoacan, Mexico

Ingo Arndt / Close-up of wing pattern on Monarch butterfly (Danaus plexippus) USA

Ingo Arndt / Monarch butterflies (Danaus plexippus) covering tree trunk, early morning, overwintering colony, Michoacan, Mexico

Ingo Arndt / Aerial view of a colony of Monarch butterflies (Danaus plexippus) overwintering in trees, Michoacan, Mexico

Ingo Arndt / Monarch butterflies (Danaus plexippus) covering tree trunk, early morning, overwintering colony, Michoacan, Mexico

Ingo Arndt / Pupa of Monarch butterfly (Danaus plexippus)

Ingo Arndt / Monarch (Danaus plexippus) butterflies drinking on wet forest ground, Angangueo, Michoacan, Mexico

Ingo Arndt / Close-up of foot claw of Monarch butterfly (Danaus plexippus) USA

Ingo Arndt / Pupa of Monarch butterfly (Danaus plexippus)

Ingo Arndt / Aerial view of the coniferous forests, with Oyamel fir trees where Monarch butterflies (Danaus plexippus) overwinter, central highlands, Michoacan, Mexico

Ingo Arndt / Branch of tree covered with clusters of Monarch butterflies (Danaus plexippus), due to it being early morning their wings are closed, later they will open to bask in the sun, Michoacan, Mexico.

Ingo Arndt / Monarch butterfly (Danaus plexippus) egg (approx 1mm) on the underside of a Milkweed leaf (Asclepias sp), USA

Ingo Arndt / Monarch butterfly (Danaus plexippus) caught in an Orb weavers web with spider about to feed on it, Cape May, New Jersey, USA

Ingo Arndt / Monarch butterfly (Danaus plexippus) feeding on Goldenrod nectar, East coast, USA.

Ingo Arndt / Tree trunk covered with members of a colony of Monarch butterflies (Danaus plexippus), some of them have their wings open and are basking in the sun, overwintering colony, Michoacan, Mexico

Ingo Arndt / Monarch butterflies (Danaus plexippus) gathered round water to drink, overwintering colony, Michoacan, Mexico

Ingo Arndt / Male Monarch butterfly (Danaus plexippus) feeding on nectar of Goldenrod flowers, East coast, USA

Ingo Arndt / Tree covered with Monarch butterflies (Danaus plexippus), early morning (before dawn) their wings are closed, Michoacan, Mexico.

Ingo Arndt / Monarch butterflies (Danaus plexippus) flying, overwintering colony, Michoacan, Mexico

Ingo Arndt / Photographer Ingo Arndt with the pilot of an ultralight aircraft on a flight to photograph aerial images of Monarch butterfly colonies, Michoacan, Mexico

Ingo Arndt / Trees covered in Monarch butterflies (Danaus plexippus) from the largest colony, El Rosario, Michoacan, Mexico

Ingo Arndt / Tree trunk covered in Monarch butterflies (Danaus plexippus) some of them have opened their wings and are basking in the sun, overwintering colony, Michoacan, Mexico

Ingo Arndt / Aerial view of a colony of Monarch butterflies (Danaus plexippus) in trees, El Rosario, Michoacan, Mexico. At midday they open their orange coloured wings and bask in the sun which makes the trees ap...

Ingo Arndt / Monarch butterflies (Danaus plexippus) drinking from pool of water, overwintering colony, Michoacan, Mexico

Ingo Arndt / Monarch butterflies (Danaus plexippus) drinking from pool of water, overwintering colony, Michoacan, Mexico. Not available for print sales

Ingo Arndt / Monarch butterflies (Danaus plexippus) flying and resting in trees, midday, overwintering colony, Michoacan, Mexico

Ingo Arndt / Close-up of Monarch butterfly (Danaus plexippus) head, recenlty emerged and still undamaged, USA

Ingo Arndt / Close-up wing detail showing characteristic dark spot next to vein on hindwing of a male newly hatched Monarch butterfly (Danaus plexippus), USA

Ingo Arndt / Monarch butterflies (Danaus plexippus) drinking from pool of water, overwintering colony, Michoacan, Mexico

Ingo Arndt / Mass of Monarch butterflies gathered on tree {Danaus plexippus} Pismo SP, California, USA

Ingo Arndt / Monarch butterflies at rest {Danaus plexippus} part of annual mass migration, Pismo State Park, San Luis, California, USA

Nick Hawkins / Monarch butterfly (Danaus plexippus) feeding on Goldenrod, New Brunswick, Canada, September.

Nick Hawkins / Monarch butterfly (Danaus plexippus) emerging from chrysalis, photographed on white. New Brunswick, Canada, September. Sequence 8 of 8

Nick Hawkins / Monarch butterfly (Danaus plexippus) emerging from chrysalis, photographed on white. New Brunswick, Canada, September. Sequence 7 of 8

Nick Hawkins / Monarch butterfly (Danaus plexippus) emerging from chrysalis, photographed on white. New Brunswick, Canada, September. Sequence 6 of 8

Nick Hawkins / Monarch butterfly (Danaus plexippus) emerging from chrysalis, photographed on white. New Brunswick, Canada, September. Sequence 5 of 8

Nick Hawkins / Monarch butterfly (Danaus plexippus) emerging from chrysalis, photographed on white. New Brunswick, Canada, September. Sequence 4 of 8