Permanent residency by self-poisoning

(20 October 2017) When they finally made it to our shores these tourists wanted only one thing: poisonous weeds left by exhausted sailors. Whom are we talking about?
Unlike privet and cane toads, the Aussies have embraced these invaders as part of their own ecosystem: ‘true blue’, orange Monarch butterflies.

Milkweed (photo internet)

It happened for thousands of years. Storms and cyclones moved the Monarch butterflies from North America to the Pacific Islands and Australia. Upon arrival the exhausted travelers had to do what all travellers (and non-travellers) like best: procreate. But the offspring did not survive. The Monarch butterflies’ host plant, which it relies upon for food and protection in the caterpillar stages, is a milkweed, a group of plants which exudes a milky, latex-like poison; we also call it the cotton bush. These specific milkweeds were not native to the Islands and Australia, so it was not until these plants arrived to our shores that the storm and cyclone driven butterflies had a chance to establish themselves in Downunder.
Now, here comes the interesting thing. According to the naturalist George Gibbs (in ‘Ghosts of Gondwana’) the first milkweeds arrived in the mid 1800s when “sailors discarded their worn-out mattresses and pillows filled with milkweed floss. The seeds of this kapok substitute, germinated and introduced the plants to islands between America and Australia.” Others reckon that the weed was introduced because its poison was used to treat skin cancer. But I like the other story better…. Anyway, the Monarchs that managed to survived arrived around 1870.
Remains the question why the Monarch caterpillars need the poison. Well, they store the poisonous juices of the milkweed in their own skins, giving them a bitter taste which is very unappealing for predators. That helps to survive. And obviously, it is a very good way to get permanent residency as well.

The caterpillar: f/11, 1/6 sec, ISO 200, tripod. 60 mm macro lens. Even the slightest movement of the twig causes problems with 1/6 second exposure time. I took about 20 photos to get one acceptable result.

Christmas present
Ever thought of sending a copy of Green Island in the Sky to friends and relatives elsewhere: the best local present available! Do it now, to be in time for Christmas (or… Dutch only, St. Nicholas). Available at over 20 points of sales on the mountain.