Right now, for just six weeks, the stunning Wanderer or Monarch Butterfly lives its short, busy life in many Australian backyards across Australia.
Looking at these beautiful butterflies you may ask yourself – at what time does an immigrant become a native?
Originally at home in North America, the Wanderer Butterfly arrived in Australia as recently as 1871, and once its host plant, the Milkweed of the genus Asclepias, arrived as well, the butterflies began to flourish.
All throughout summer, with one generation following another, the females lay single eggs under the leaves of milkweed.
When the caterpillars hatch, they eat the leaves and the flowers of the plant. With their colourful racing stripes, they look just as pretty as their parents, but in the animal world they are a clear warning signal. The caterpillars feed on the plant’s milky sap, which makes them toxic and protects them from predators.
The caterpillar’s feeding frenzy lasts only two weeks before they pupate on the plant inside a green and golden cocoon. Another three weeks later, a Wanderer Butterfly emerges to start the cycle all over again.
The toxin in its body will keep the adult butterfly safe from most predators but the Currawong.
Most butterflies spend winter as larvae or as a pupae, waiting to emerge as a butterfly in summer. Monarch butterflies and Crow Butterflies however spend winter as adults, which gives them a head start for the mating season in spring.
In summer, the Monarch Butterfly is common along the east coast of Australia from Queensland to South Australia, and in south-west Western Australia. They like the warmth, so as the days get colder, some just pack up and leave for warmer regions. But many stay behind, too far south to travel, and they have their own strategy to survive the cooler months with their limited food supply.
From April they gather by the thousands and hang in large clusters from the trees. The first animals to arrive in the cluster are males, with the females following about a week later.
During the day the butterflies fly around the trees, but as the temperature drops they settle for the night in their clusters. They spend much of their time in dormancy, eating and drinking very little. This phenomenon is known from sites in the Sydney Basin and Hunter Valley, as well in the Mt Lofty Ranges, near Adelaide. The butterflies return to the same trees every year and stay until September. Then it is time to mate and fly off to find food plants for the offspring.
DID YOU KNOW?
The wings of the Wanderer Butterfly measure 9 cm and carry it at a speed of up to 40 km per hour.
If you are cleaning up any milkweed plants in your neighbourhood, make sure you dispose of them in the waste bin. They are a weed after all and can damage your surrounding bushland. If you would like to attract the butterflies and prefer our beautiful native plants, plant a bottlebrush and avoid using pesticides around the garden.