More about garden orb weavers

Description: The garden orb weavers (or Eriophora spiders) are heavily built and can be a variety of colours (mostly reddish brown or grey) and designs (e.g., leaf shaped pattern on the abdomen). Females measure up to 30 mm in body length, with the abdomen measuring 20 mm alone. Males measure 15 mm to 20 mm in body length.

Toxicity: Most are reluctant to bite. Symptoms, if any, include mild local pain, numbness & swelling (nausea and dizziness can occur but is rare).

General Ecology: They are found in all states and territories of Australia in a wide range of habitats but their preferred habitat is bushland with the wheel webs strung above the ground between trees across a trail, creek or stream. Cryptic colouring helps to camouflage these spiders as they hide beneath leaves and bark during the daylight. They prey on flying insects such as flies, beetles and cicadas. The spider is sensitive to the slightest vibration in the web. When an insect is snared the spider races to the prey and immediately envelops the prey in silk. Once secure in the silk the spider sinks its fangs into the insect until movement ceases. They're predators are birds such as honeyeaters, as well as reptiles.

Web Construction: The complete wheel webs use the minimum of silk and are continually rebuilt - they are not as permanent as some wheel webs (e.g., Argiope . the simpler design has a shorter construction time and can be built almost anywhere. Construction begins soon after sunset and takes approximately 45 minutes. It has been suggested that the spiders are aware of the factors that influences whether insects will fly on any given night. These influences include cloud cover, rain, wind, heat, humidity, insect breeding seasons and phases of the moon. When conditions are unfavourable, they make no attempt to construct their snares.

1. Secret to bridging spaces between trees is directly associated with air currents. The spider casts out a tuft of silk into the rising warm air. The currents lift it and it floats until it entangles in a distant object. (Sometimes the spider will drop from its vantage point on its safety line and just before reaching the ground will start to climb back up. The spider then waits for the dangling silk to be carried away in the breeze).

2. Once attached and the spider is assured of the strength of the anchor it moves along the silk doubling its thickness. Reinforcing the contact point with additional silk, the spider continues to add silken thread to the line increasing its strength.

3. Attaching more thread to both ends, the spider moves halfway down the line and then drops to the ground. The weight of the spider pulls the thread into a Y-shape, which become the first of several radial threads forming the spokes of the wheel. The hub of the web is established at the fork where the Y begins.

4. The spider then constructs the frame around the outside, attaching the thread to surrounding objects.

5. The spokes are then constructed. The spider attaches the radial thread to the hub, walks along an existing line and then attaches it at the other end to the outer frame.

6. A spiral pattern is then created from the hub, first using dry thread and later replaced by sticky thread.

7. After the web has served its purpose for the night, the spider gathers it into a ball and places it in its mouth for some time to extract protein. The ball is eventually dropped to the ground. Only the bridge is left in tact to see another day and a new web.

Animated example