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All pictures are copyright of Jaap de Roode.

  
 

A female monarch butterfly laying eggs on the medicinal milkweed Asclepias curassavica (tropical milkweed).

  

A healthy female monarch butterfly nectaring on Lantana.

  
             
 

Fieldwork in a Mexican monarch overwintering site: note the trees covered in monarch butterfies.

  

Monarchs take to the sky in Mexico.

 
             
 

Monarch butterfly caterpillars regularly have to share their milkweed food plants with oleander aphids (Aphis nerii).

 

In the lab, monarchs are reared in plastic tubes with milkweed plants.

 
             
 

Eleanore and Rachel setting up a big lab experiment.

  

When monarch butterflies are heavily infected with the protozoan parasite Ophryocystis elektroscirrha, they can sometimes get stuck to their chrysalis. This means death for both monarch and parasite.

  
             
 

Wild-caught butterflies at the Pismo Beach overwintering site in California produce a fluttering piece of art.

  

Carlos and Rachel sample milkweed leaves for chemical analysis.

  
             
  A first instar monarch larva feeding on Asclepias incarnata (swamp milkweed).   Monarchs migrating from eastern North America to Mexico stop over at the St Marks Wildlife Refuge.  
             
  Jaap, Rachel, Carlos, Eleanore and Mike on fieldwork in Mexico.   Monarch butterflies catching the sun on an oyamel tree in a Mexican overwintering site.  
             
  A female monarch butterfly laying eggs on the medicinal milkweed Asclepias curassavica (tropical milkweed).   In the lab, oviposition preferences of monarchs are tested by placing them in a cage with two milkweed plants.  
             
  In western North America, monarchs migrate to groves along the Californian Pacific coast, such as in Pismo Beach.   A second and fifth instar monarch larva share this tropical milkweed with oleander aphids.  
             
  Monarchs take to the sky in Mexico.   Getting together with Sonia Altizer's lab to do fieldwork in Mexico.  
             
  Monarchs mating in the early spring in Mexico.   A female monarch butterfly laying eggs on the medicinal milkweed Asclepias curassavica (tropical milkweed).  
             
  Monarchs cluster together for warmth in a Mexican overwintering site.   Jaap collecting monarch butterflies from the trees in Mexico.  
             
  Rachel and Mike surrounded by Mexican butterflies.   A female monarch butterfly laying eggs on the medicinal milkweed Asclepias curassavica.  
             
  A fifth instar monarch caterpillar on Asclepias curassavica (tropical milkweed).   Visiting the Mexican city of Morelia after fieldwork.  
             
  Monarchs hang in clusters from the trees in Mexico.   When monarch butterflies are heavily infected with the protozoan parasite Ophryocystis elektroscirrha, they can sometimes get stuck to their chrysalis. In this case, a paper wasp takes advantage of the situation.  
             
  A healthy monarch butterfly about to emerge from its chrysalis.   Carlos surrounded by monarch butterflies in an oyamel fir tree forest in Mexico.  
             
  In the lab, caterpillars are infected with parasites by feeding them small disks of milkweed with parasites in petri dishes.   A female monarch butterfly migrant resting in St Marks, Florida, on her way from North America to Mexico.  
             
  The lighthouse in St Marks, at the stopover for monarchs on their migration from North America to Mexico.   Rachel, Amanda and Thierry at the St Marks Monarch Butterfly Festival 2009.