Net-caster spider Click to enlarge image
Net-casting spider of the Deinopidae family. Image: Stuart Humphreys
© Australian Museum

Fast Facts

  • Classification
    Family
    Deinopidae
    Order
    Araneae
    Class
    Arachnida
    Phylum
    Arthropoda
    Kingdom
    Animalia
  • Size Range
    1.5-2.5 cm
  • Life history mode
    arboreal
  • Feeding Habits
    arthropod-feeder, carnivorous, insectivorous

Introduction

Net-casting Spiders have a unique way of catching their prey. They make a small web in the form of a net held by the front legs that can be stretched out wide to envelop an unwary insect passing by.

Identification

The spider has excellent eyesight, with a huge pair of forward facing eyes that help it to see at night. The genus commonly encountered in gardens is Deinopis. Another genus, Avella, has less prominent eyes.

Net-casting Spiders have stick-like bodies, with spindly legs. Members of the genus Deinopis have a large, prominent pair of eyes at the front of the head (hence their other common name of Ogre-faced Spiders) and vary in colouring from fawn to pinkish brown or chocolate brown. Members of the genus Avella have smaller eyes and have subtle greenish brown to grey patterning. The males are smaller and even more slender and stick-like than the females, and can differ from them in their colour and patterning.



Habitat

They are often seen on fine summer nights among garden shrubs and trees.

Distribution

Net-casting Spiders are widely distributed in forest habitats of south-eastern Australia.



Feeding and diet

They are nocturnal, feeding on ants, beetles, crickets and other spiders.

Other behaviours and adaptations

When at rest, the spider hangs from vegetation with its head downwards, its long body and long, thin front and back legs held together on each side, giving the spider a stick-like appearance. The spider also assumes a head-down position when it is waiting for prey, except that it now holds its net with the front four legs and suspends itself by the back legs and spinnerets from support lines to surrounding foliage. The net is a blueish-white square of wool-like cribellate silk, whose coiled lines are designed to stretch and entangle prey. In order to have an aiming point, the spider often drops splashes of white faecal droppings onto the leaf or bark substrate over which it is poised. When an insect walks across this 'target', the spider plunges its net downward to envelop and entangle it. If successful, the spider silk-wraps the prey item, bites and paralyses it, and then feeds on it. Net strikes will also be made at flying insects that stray too close. An unused net is sometimes stored by hanging it on nearby leaves for the next night's hunting, or the spider may eat it.

Life history cycle

After mating has taken place the female Net-casting Spider constructs strong spherical brown flecked egg sacs. Each sac is suspended among low foliage, either dead or living, by a short silk stalk and is further disguised using leaf debris.

Net-casting Spiders mature in summer, when mating and egg-laying occurs.

Danger to humans

These spiders are not considered to be dangerous.

References

  • Gray, M. 1997. Australian Spiders. Australian Museum Information Disk. Edited & produced by Bill Rudman.
  • York Main, B. 1976. Spiders. William Collins Publishers Pty Ltd, Sydney NSW.