While enjoying a drink on her deck every afternoon at 5.30pm, a colleague of mine has noticed a spider building its web – in exactly the same location. Every morning at 7am, while having her coffee, she observed the spider ‘eating’ its web, then tucking himself under the bark of a tree. Same spider, same spot, at the exact same time each morning/night.
Turns out, this spider belongs to a common family of orb-weaving spiders – Araneidae. The family is so widespread across Australia it is likely to have evolved into up to 260 different species, each with variations in colour, size and form. This fella is a Garden Orb Weaver (Eriophora transmarina).
And my colleague’s observations were spot-on: these spiders are nocturnal, and are notorious for having a predictable and fastidious routine. They weave large, round, intricate webs each night, between trees or bushes where insects are likely to fly. Once they find a rewarding spot they stick to it. This particular spider would have his web constructed in about 1.5 hrs each night.
Overnight, the spiders rest in the centre of their webs, waiting for prey (eg. flies, beetles and bugs). At dawn, the spider dismantles its web by ingesting the silk. Advantages of this are:
- A home-made, protein-rich breakfast each morning
- No clues are left for potential predators (wasps, other spiders, birds) as to the spider’s whereabouts
- A clean, clutter free web each day
However, it seemed that the spider was leaving the top of its web (the bridge thread) behind each morning. Advantages of this are:
- Saves precious building time the following afternoon
- Warns other spiders that spot is taken
- Can lead male spiders to a female
- If the bridge thread is still intact each evening, the spider assumes no ‘large’ predators (eg. people with brooms) are in the area, and the area is safe
During daylight, the spiders watch over their web-site from a well concealed vantage point. Then, at dusk – it starts all over again!
The Garden Orb Weavers are as predictable as your morning coffee and evening tipple. And it just proves you don’t have to go a long way to find something interesting.