Black house spider (Badumna insignis)
Grey House Spider(Badumna longinqua)
Pest Snapshot - Black House Spider
- Scientific name: Baduma insignis
- Identification: Mostly black spider with mottled abdomen and brown / black legs. Body up to 18mm long. Leg span up to 30mm.
- Health threat: Low
- Bite pain: Moderate
- First aid: Standard spider bite first aid. Seek medical attention if unsure about spider identification or severe reaction.
- Web description: Dense, funnel shaped web
- Web locations: Around windows, doors and eaves (often near light sources), on tree trunks and logs.
- Main pest season: Spring to Autumn
- Indoor/Outdoor pest: Mainly outdoors
- Difficulty to control: Easy
Black House Spider Information
Other names
The black house spider is sometimes called the common black spider.
Identification
Female: Body up to 18 mm (with 30 mm leg span)
The black house spider is dark brown / black carapace with a charcoal grey abdomen with white markings / hairs. The females are larger than the males.
The grey house spider has a greyish carapace (a similar colour to its abdomen) and grey-brown banded legs.
Male: Body up to 10 mm
The legs appear longer in relation to the body than the female.
Web:
Both black and grey house spiders produces messy web, with an obvious a funnel-type centre (which is why homeowners can sometimes be concerned they have a funnel-web spider). The web is generally kept clear of debris.
Black house spider web
The black house spider produces messy, dense web, with an obvious a funnel-type centre (which is why homeowners can sometimes be mis-identified as a funnel-web spider). The web is generally kept clear of debris.
Life-cycle
Mating:
Female black house spiders never leave their webs, so the males need to go looking for a mate. Once they have found a female they pluck the web to get her attention and make sure she is receptive to mating. Once together they tend to remain together for a couple of days, mating several times.
Eggs:
Black house spiders produce egg sacs which are secured within the funnel part of the web.
Baby black house spiders:
The baby redbacks or spiderlings hatch from their eggs within a couple of weeks and disperse. Sometime the spiderlings can remain around the perimeter of the web picking up smaller prey.
Life-span:
Black house spiders live for about 2 years.
Where are black and grey house spiders found?
Black house spiders and their close relatives grey house spiders (sometimes called brown house spiders) are found throughout New Zealand, having been introduced accidentally from Australia.
They are normally found on tree trunks, logs and under rocks although around buildings they are found:
- Around window frames, doors and eaves
- In vents and weep holes
- Along fencing (especially inside tubular fencing)
- Under rocks and wood piles
- In the sub-floor (if you have one)
- Under outdoor furniture and BBQs
- In post boxes and electrical boxes
Black house spiders are more likely to be found around buildings.
What do black house spiders eat?
Black house spiders will capture and feed on a wide range of insects.
Other information:
Black house spiders are a favourite food of white-tail spiders.
Prevention tips:
Other than keeping rubbish and stored goods away from the perimeter of the property, the only way to eliminate a black house spider problem or prevent them building their webs is with a professional pest treatment.
Other types of spider.
Black House Spider Bite Information
Symptoms
Black house spiders are a timid spider and will retreat quickly into its web when disturbed. However, black house spider bites are moderately venomous and so if bitten its bite can be quite painful.
Bite Symptoms:
- Localised pain and swelling
- Occasionally nausea, vomiting, sweating and dizziness
Treatment
First aid:
- Apply an ice pack to the bite area
- (Capture or take a photo of the spider for identification)
- Seek medical attention if symptoms persist
As it can often get confused with other black spiders such as mouse spiders or funnel web spiders which are very dangerous, if you are not confident you have correctly identified the spider, you should treat the spider bite as per a funnel-web bite. ie. Immobilise the victim, apply a pressure bandage to the limb and immediately seek medical assistance.
Medical disclaimer: The information provided on this website is for educational purposes only and does not substitute for professional medical advice. If in doubt about identifying the spider or understanding the required first aid, seek medical attention immediately. ff the victim experiences a significant reaction to the bite (no matter which spider), seek medical help immediately.
In case of emergency call 111. If uncertain about what to do call the National Poisons Centre on 0800 764 766.
How to get rid of black house spiders?
A professional black house spider treatment starts with a good inspection to ensure all webs and potential hiding places are identified.
Typically, a professional treatment will consist of a thorough perimeter spray, focusing on windows, doors, eaves and other entry points, which will target most of the common black house spider hiding spots.
Spraying webs and hiding places with a professional residual spray will achieve excellent results. Bifenthrin based products have an excellent reputation as a long lasting spider treatment.
Most professional pest manager will ofter a 6-month warranty on web-building spiders, such as the black house spider.
Webs can be removed 2-3 days after the treatment. Any webs should be brushed down and not washed away with water, as it will also wash away the insecticide, reducing the duration of protection.
Black House Spider FAQ
Are black house spiders dangerous?
Although black house spider bites are moderately venomous, they are not considered particularly dangerous as they are not an aggressive spider. They will generally retreat quickly, deeper into their web when disturbed, so bites are not particularly common. There is no anti-venom available and no specific medical treatment is required.
Are black house spiders dangerous for dogs?
There is no information to suggest black house spiders are specifically dangerous to dogs or other pets. If a dog is bitten, seek veterinary assistance.
How long do black house spiders live?
Black house spiders only live for about 2 years.