Black house spider

Black house spider
	;
Scientific classification
Kingdom:	Animalia;
Phylum:	Arthropoda;
Class:	Arachnida;
Order:	Araneae;
Family:	Desidae;
Genus:	Badumna;
Species:	B. insignis;
Binomial name
	Badumna insignis; L. Koch, 1872

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The black house spider (Badumna insignis) is a common species of Australian spider. It lives in most areas of Australia and it prefers urban habitat. Its web is a messy-looking construct of triangular sail-like shapes, usually stretched in the corner of the walls, windows etc. Somewhere in the web is a funnel-shaped entrance to the nest, where the spider spends most of its time, waiting for prey. It is this feature that gets the black house spider confused with the very aggressive and venomous Sydney funnel-web spider. These two spiders do not have similar appearance, size or usual habitat (funnel webs live on the ground, house spiders high up), and the confusion is simply due to panic and ignorance.

The black house spider is venomous, but is not considered dangerous to humans, except for possible infection of the bite. They are quite shy, only coming out of the nest to capture their prey, then quickly retreat.

They seem to be quite attached to their location, and their webs look more and more untidy over time, as the spider adds to it and repairs it with different kinds of silk.

The black house spider is a favoured prey of the white-tailed spider.

[edit] Habitat and Distribution

Black and Grey House Spiders are widely distributed in southern and eastern Australia. Their webs form untidy, lacy silk sheets with funnel-like entrances. Black House Spiders are found on tree trunks, logs, rock walls and buildings (in window frames, wall crevices, etc). Badumna longinquus may be found in similar locations and often builds webs on foliage.

[edit] Identification

The Black House Spider (Badumna insignis) is a dark robust spider, with the female (up to 18mm) being larger than the male (about 9mm). The carapace and legs are dark brown to black, and the abdomen is charcoal grey with a dorsal pattern of white markings (sometimes indistinct). B. longinquus (Grey House Spider) is a slightly smaller (14mm) species with a greyish carapace and grey-brown banded legs.

The webs of Black House Spiders have a 'funnel-like' shape, which is sometimes confused as a Funnel-web Spider web. However, the two spiders are not at all similar in appearance, size or life history. See the Funnel-web Spider factsheet to compare the two spiders. The retreat of a true Funnel-web Spider is often less funnel-like and is usually a burrow in the ground. Some funnel webs have burrows in tree-trunk crevices but their web entrances are disguised with detritus (eg, bark) particles embedded in the silk, whereas the silk of Badumna webs is clean.

[edit] Habits, Mating and Reproduction

The female spider never leaves her web unless forced to, but keeps on repairing it - old webs can look grey and woolly from constant additions of silk. Males, when ready to mate, go in search of females in their webs. The male plucks the web of the female to attract her attention. Once the male has made sure that the female will be receptive, he can safely approach and inseminate her with his palps. They may then stay together for several days and may mate again several times.

The female constructs several white silk egg sacs, which are secured within the web retreat. The female stays with the eggs until they hatch. The spiderlings then disperse. The spiders mature during summertime and live for about two years.

In the bush, Badumna spiders are found especially upon rough-barked trees which provide good shelter for their retreats amongst the cracks in the bark. Trees that have been attacked by wood-boring insects are particularly attractive, as the sap flowing from the bored holes attracts flies, beetles, butterflies, bees and ants, which the spider can prey upon easily. In the house, they feed upon household pests attracted to the light of windows and lamps, where the spiders tend to build their webs. Predators include the White-tailed Spider, as well as parasitic wasps and flies.

[edit] Bite

Black House Spiders are timid animals and bites from them are infrequent. The bite may be quite painful and cause local swelling. Symptoms such as nausea, vomiting, sweating and giddiness are occasionally recorded. In a few cases skin lesions (arachnogenic necrosis) have developed after multiple bites.