Tails Blog

Monarch Butterfly Life Cycle

Steve Coppell - Sunday, October 03, 2010

The Monarch  is one of the best known butterflies.
It was first discovered in New Zealand around the beginning of the 19th century. It originated from North America, and it is believed to have used thermals or up drafts to conserve energy for its long journeys as it migrated, eventually finding its way to our shores here in New Zealand. Monarchs have been known to travel up to 9500 km s a year. It`s believed they guide themselves using the position of the sun and the magnetic field of the earth.

Monarchs are cold blooded. So you usually only find them in your garden between November and April. During the winter months they will hibernate in a nice dry spot such as inside branches of a Conifer tree.
Monarchs are foul tasting and poisonous to many of their potential predators, due to the Cardenolide Aglycones they ingest as they feed on milkweed.

Swan Plant

 You will need to plant Milkweed in your garden if you want to encourage the monarch to lay eggs. There are eight varieties of milkweed in New Zealand, of which the swan plant, giant swan, and tropical milkweed are best known. You should be able to purchase one of these from your local garden shop, from early October. Make sure the plant has been grown organically as traces of sprays may kill the caterpillars. If you start with seedlings, you will need to plant early as you won`t have a mature plant until the following year. It is important to wait for your plant to reach maturity before encouraging monarch butterflies to lay their eggs on it, as the caterpillars are very fussy and will only eat milkweed. A mature plant is also necessary as the caterpillers are ferocious eaters and need large and healthy foliage to feed on. One of these creatures will eat 18 leaves during the two to three weeks it is a caterpillar. If you do run out of food, some caterpillars will feed on pumpkin, courgette or cucumber though, professional breeders say these should only be a temporary substitute if you are having difficulties finding another plant.
Breeders also say that feeding these vegetables should be reserved for caterpillars that are more than 2.5cm long, as younger ones can`t digest them.
In order to avoid a shortage of food , try to limit the number of caterpillars to about 10 to 15 per plant. This will give them a better chance of surviving and becoming healthy butterflies.
It`s best to grow your milkweed plant in a pot in a sunny spot on a balcony or deck, when the Monarch has laid its eggs on your plant you can move them inside. Otherwise drape them in netting to stop more eggs being laid. This will also protect the caterpillers from predators such as wasps, preying mantis, sheild bugs and spiders.
Also remember the plants are susceptible to snails and slugs, so sprinkle sawdust around the base to keep pests away. You can protect eggs from hungry ants by wrapping a piece of oil soaked cloth around the base of the plants stem, or by placing your plant in a moat of water if it is in a pot.

Monarch butterflies lay their eggs on leaves of milkweed plant.

Monarch egg

Caterpillar hatches

Caterpillar feeds on egg then starts on milkweed

Towards the 4th week the caterpillars stop eating and search out a high sheltered position where they anchor themselves by a silk thread. Hanging upside down they shed their skin. They then create a crysalis, which takes a few hours to harden.

Over a few weeks, the crysalis developes a vivid pale green colour and gold studs, then darkens and becomes translucent.