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We share our cold climate garden with macropods, echidnas, birds and many arthropods including insects, spiders etc.
One wildlife observation had us scratching our heads. Hanging from an Acacia baileyana, about one metre above the ground, were six papery sacs.
We found, via the internet, that they were the egg sacs of the Magnificent or Bolas Spider.
The female Magnificent Spider is about two cm long whilst the tiny male is only 1.5 millimetres in length. The female has very distinctive markings with two bright yellow knobs on her white abdomen. There are also salmon-coloured spots and blotches on her body. Fine, long hairs cover legs and body.
The Bolas Spider using a cunning method to capture prey. At night the female spins a line of silk with a sticky globule on the end. The Bolas name refers to the South American throwing weapon made of ropes and weights. It is thought that the sticky globule may contain a pheromone mimicking the scent of female moths, attracting unwary male moths. The spider twirls the thread when it senses the moth’s beating wings. The moth becomes stuck to the globule when close enough. Prey is eaten immediately or stored for later wrapped in silk. Spiders may respond to vibrating guitar or other instrument strings.
Magnificent Spiders hide during the day in a retreat of leaves bound together with silk.
Little is known about their courtship and mating. When egg development starts, the female’s abdomen swells massively. Over several nights distinctive spindle-shaped egg sacs are constructed. Each sac contains about 600 eggs. Up to seven sacs are attached to a branch. The photo shows six egg sacs. When the baby spiders emerge, in late winter and early spring, they disperse by spinning a thread and being carried away by the wind.
There are three Australian species and are found in New South Wales and Queensland.
We first found the egg sacs in January. They were somewhat weather-beaten, but still recognizable in October of the same year.
Bolas Spiders pose no threat to humans.
The wildlife, in our cold climate garden, is a constant delight and interest.