Black House Spider

Scientific Name: Badumna insignis

How to identify a black house spider

The Black House Spider belongs to the family Desidae. Related species are found throughout Australia.

The Black House Spider (Badumna insignis) is a dark robust spider, with grey hairs usually visible on the carapace. Females are larger than males but there is a great range in adult sizes. The carapace and legs are dark brown to black, and the abdomen is charcoal grey with a dorsal pattern of white markings (sometimes indistinct).

The web structure includes one or more 'funnel-like' entrances to the spider’s retreat, which is sometimes misunderstood as a Funnel-web Spider web. However, Black House Spiders are not at all related to Australian funnel-webs, nor similar in appearance, size or life history. The retreat of a true Australian Funnel-web Spider (famiy Atracidae) is usually less funnel-like and is often a burrow in the ground. Common Southern Tree Funnel-webs make burrows in tree-trunk crevices in similar habitats to Black House Spiders, but their crescent-shaped web entrances are disguised with detritus (eg, bark) particles embedded in the silk, whereas the silk of Badumna webs is exposed.

Where are black house spiders commonly found?

Black House Spiders are found on tree trunks, logs, rock walls and buildings (in window frames, wall crevices, etc). Whilst juvenile spiders may be quite exposed, the ones that survive to adulthood have usually acquired a secure retreat beneath bark or in a deep crevice.

Why are black house spiders considered a pest?

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 have developed after multiple bites.

What is the biology and lifecycle of a black house spider?

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.

Management Tips for Black House Spiders

General Spider Prevention Tips

• Keeping garden beds and rubbish away from the edge of the house will significantly reduce the spider population.

• If garden beds next to the house are kept in place, it is important to keeping vegetation trimmed back from the edge of the house and paths.

• Make sure insect screens and draft excluders are in good repair and well fitting

• Keep clothes and shoes off the floor to reduce spider hiding places.

General Spider Control Tips

• The best treatment for web-building spiders is to spray their webs and hiding places with an insecticide (ready to use pump back or aerosol). The key tip to get the best performance is to wait a day or two after spraying before brushing down any webs. This ensures the spiders will have picked up a lethal does of insecticide (by walking on the web) and by using a brush (rather than hose), you can ensure the insecticide remains in place to prevent new spiders taking up residence.

• To prevent web-building spiders take up residence in the first place, spraying around doors, windows and vents, as well as under eaves and guttering delivers excellent results. As these spots tend to be sheltered from sun and rain, the treatment can last many months.

• It is a lot more difficult to prevent running spiders entering the home. Carrying out a preventative spray around the perimeter of the home and any openings will have some benefit, although running spiders often walk on the tips of their legs, preventing them from picking up a lethal dose of insecticide. However, if you carry out a preventative treatment for web-building spiders and other insects, the numbers of running spiders will be greatly reduced, as there will be little prey for them to feed on.

• Even with the best control program the occasional spider may get in. A crawling insect aerosol should be kept on hand to spray the occasional unwanted spider. Ensure the spider receives a good dose and keep your distance.