White Porch Spider

Introduction

The White Porch Spider, Cryptachaea gigantipes, is commonly found living on the outside of houses in some parts of Eastern Australia. For many years this native species was confused with the introduced cosmopolitan species Parasteatoda tepidariorum. The common name, White Porch Spider was coined in New Zealand, where it has been spreading since about 2000.

Identification

The White Porch Spider is in the family Theridiidae (also known as comb-footed spiders), and is related to the Redback and Cupboard spiders. The general body shape of the White Porch Spider is somewhat similar to these species, but all parts are generally pale coloured with a variable amount of darker markings. Males are also generally more strongly coloured than females.

The most obvious character is the extremely long front legs. In males, each long section between the joints of the first leg is longer than the total body length, while in females each of the leg sections approximately equals the body length.

Habitat

The natural habitat of this species is beneath rocky overhangs, in crevices and cave entrances in the sandstone country of Sydney and similar rocky habitats, along Australia’s east coast. In this environment it can be extremely well camouflaged.

They also find homes around and sometimes in human buildings, where areas such as overhanging eaves and verandas provide excellent habitat. These kinds of places not only have shelter but often an abundance of insect prey that are attracted to house lights.

Like its relatives, White Porch Spiders build a tangled-looking web with sticky lines (a gum-footed web). While a Redback spider usually has a strong secluded retreat, the White Porch Spider’s retreat area is far less dense, and is usually in full view. However, the spider can be difficult to see as it rests close up against the substrate.

Distribution

The White Porch Spider is common in many areas on the east coast of Australia, from the very south eastern corner of Queensland south to Victoria and across Tasmania. It is unclear how much this distribution has been affected by human translocation, but if any records from South Australia are validated they will almost certainly represent human-mediated spread.

It is also recorded on Norfolk Island and has been introduced to New Zealand, where it has spread widely on the North Island since about 2000. In New Zealand it has only been found in human-modified environments.

Life history

Adult males travel along silk lines in search of females and are often found in or near female webs. Egg sacs may hold up to 250 eggs contained in brownish silk and are suspended in the female’s web near her usual resting position.

Spiderling emergence time depends on temperature, usually between 4 – 5 weeks in the spring and less in warmer weather. The young remain in their mother’s web for some time and are protected by her while they remain together but they disperse rapidly as younger siblings begin to emerge from later egg sacs. Adult spiders may be found all year but are most common in the warmer months.

Prey and predators

Various kinds of insects and spiders have been recorded as prey. Insects include beetles, flies, bugs, moths and caterpillars. Spider prey includes both those that move along silk lines, such as Net-casting and Black House spiders, and ground dwellers such as Wolf Spiders.

White-tailed Spiders feature as both prey and as a predator, as do spiders of their own species. Other known predators include Pirate Spiders and wasps.

Danger to humans

Bites are rare but two that were reliably recorded (compared to 68 for the Redback Spider in the same study) caused symptoms such as pain, redness, swelling and muscle aches, with symptoms lasting for up to 24 hours. The pain was less severe than that caused by Australian Redback spiders.

First aid

Usually no first aid is required. A cold pack can be applied to help reduce any pain or swelling at the site of the bite.