Topic: Orb web spiders
Is part of topic What spider is that?
Scientific name: Family Araneidae
What do they look like?
This group is highly variable in size and colour. The most common species in New Zealand is the garden orb web spider Eriophora pustulosa. This species has a tremendous range of colour, although most commonly individuals are shaded with browns and greys.
Despite the variability in colour pattern, this species can be readily identified by the presence of five small knobs at the end of the abdomen. Some other New Zealand species are brilliant shades of yellow, green, orange, and other colours.
Where are they found?
These spiders are found throughout New Zealand. Eriophora pustulosa is also found in Australia, and is thought to have ballooned (been carried by strong winds) into New Zealand. It is the commonest species of orb web spider in New Zealand and is very common in gardens.
What are their habits?
Like the two-spined spider, also a member of this family, these spiders are renowned for their cartwheel-like webs. This web shape is probably the one most commonly associated with spiders.
A typical orb web spider will construct or repair its snare by night, then sit in the centre. This central portion of the web is dry, but the spiral of silk a little further out from the centre is sticky. This is the part of the web that actually traps prey.
By day, the spider usually hides outside the web, but will rest a leg on a thread that runs to the centre. This allows the spider to remain out of sight of predators while still being aware of any prey that gets caught in the web. The egg sac of Eriophora pustulosa resembles a messy tuft of wiry threads and is usually grey-green in colour.
These spiders have a number of enemies. Both German wasps and mason wasps will attack them, although each wasp has quite a different goal.
The German wasp will feed directly on orb web spiders. The female mason wasp has another objective. Using her stinger, she will paralyse the spider, then take it back to her lair. There she will place the spider in a mud-walled chamber she has built as a nursery. She then lays an egg. A grub hatches from the egg and consumes the helpless but still living spider.
What is their bite like?
Bites are uncommon and usually produce little more than mild local pain and slight blistering.
On display at Te Papa?
In the forest invertebrates display in Mountains to Sea. NatureSpace also has a resin embedded specimen available for viewing on request.