Identification
Physical Characteristics
Size: Females are the larger sex, with a body length of approximately 6-7mm. Males are much smaller and more slender, typically around 3-4mm long.
Coloration: The cephalothorax and legs are distinctively reddish-brown or orange-brown, which is the source of its common name. The abdomen is a bulbous, glossy sphere, typically light brown to dark brown, often with some faint, paler markings or speckles. It completely lacks the prominent red or orange stripe characteristic of a Redback spider.
Key Features: The most definitive features are the combination of reddish-brown legs and cephalothorax with a plain, unmarked brown, globular abdomen. The tangled, 'cobweb' style web is also a key indicator.
Biology & Lifecycle
Development & Reproduction
Reproduction Rate: Reproduction can occur year-round in the warm, stable environments found inside Australian homes. A single female can produce a new egg sac every few weeks, leading to rapid population growth if conditions are favourable.
Lifecycle Details
Egg Stage
After mating, the female produces multiple egg sacs throughout her life. Each sac is a small, fluffy, white or cream-coloured silk ball, which is hung within the tangled web. An egg sac can contain between 50 and 150 eggs. The female guards the sacs, often keeping them close to her position in the web.
Larval Stage
This term is not used for spiders; they hatch as spiderlings.
Pupal Stage
Spiders do not have a pupal stage.
Adult Stage
Adults can live for up to a year, sometimes longer in stable indoor conditions with a steady food supply. Females tend to live longer than males. Once mature, males cease building webs for prey capture and spend their shorter lives wandering in search of females.
Reproduction Rate
Reproduction can occur year-round in the warm, stable environments found inside Australian homes. A single female can produce a new egg sac every few weeks, leading to rapid population growth if conditions are favourable.
Generations Per Year
Several generations per year are possible due to the short development time and continuous breeding cycle in indoor habitats.
Development Time
The time from egg to adult can be as short as two to three months, heavily dependent on ambient temperature and food availability. Warmer temperatures and more prey lead to faster development.
Seasonal Cycle
In the stable indoor environments they prefer, there is little to no seasonal variation in their lifecycle. Breeding, feeding, and web-building occur year-round. In more exposed locations, activity may be higher in the warmer, more humid months.
Environmental Factors
The key environmental factors are a stable warm temperature, the presence of structural elements to build a web, and a consistent supply of crawling insects. Humidity is also preferred.
Habitat & Distribution
Preferred Habitats
- Dark corners of rooms, especially near the floor or ceiling.
- Inside little-used cupboards, pantries, and wardrobes.
- In garages, sheds, and outdoor toilets.
- Behind and under furniture, and in sub-floor voids.
- Warm, humid, and cluttered areas provide the ideal habitat.
Distribution Patterns
Australian Distribution
Primarily found in the warmer, more humid parts of Australia: Queensland, Northern Territory, and northern parts of New South Wales and Western Australia. It can persist in heated homes further south.
Climate Zones
- Tropical
- Subtropical
Urban vs Rural Distribution
Almost exclusively found in and around human structures in both urban and rural settings. It is a classic 'domiciliary' or house-dwelling spider.
Native Range
Pantropical. It is believed to be a cosmopolitan species originating from tropical regions, not native to Australia.
Introduced Range
Found in tropical and subtropical regions worldwide, including North and South America, Africa, and Asia.
Introduction History
The exact history of its introduction to Australia is unknown, but it has likely been present for over a century, arriving with early shipping.
Current Spread
Its distribution is stable within the tropical and subtropical zones. Its spread further south is limited by its inability to survive cold winters outdoors.
Limiting Factors
Cold temperature is the primary limiting factor for its distribution. It cannot establish permanent outdoor populations in temperate southern Australia.
Behavior & Diet
Activity Pattern
Primarily nocturnal. They remain hidden during the day and become active at night, hanging upside down in their webs to wait for prey and perform web maintenance.
Dietary Preferences
Feeding Habits
A specialist predator of crawling arthropods.
Health Risks
Always consult healthcare professionals for medical concerns related to pest exposure.
Disease Transmission
- No evidence of disease transmission. They are not known to carry any pathogens harmful to humans.
Allergens and Respiratory Issues
The accumulation of dust, spider droppings, and insect carcasses in their messy webs can potentially contribute to household dust allergens, which may affect individuals with asthma or respiratory sensitivities.
Contamination Risk
Extremely low. They do not seek out human food and tend to stay in undisturbed areas.
Vulnerable Populations
- Arachnophobic individuals may experience psychological distress.
- People with pre-existing respiratory conditions might be sensitive to the dust collected in old webs.
- There are no specific populations vulnerable to its bite.
- The main 'risk' is causing anxiety due to its resemblance to a Redback.
- No physical risk to children or pets.
Symptoms of Exposure
- A bite is highly unlikely and would likely be a tiny, painless prick.
- In the improbable event of a bite, symptoms would be trivial, possibly a minute spot of local redness that fades quickly.
- There are no recorded cases of significant envenomation.
- No medical attention is required.
- The risk of a significant reaction is virtually zero.
Transmission Methods
- The only theoretical method of venom transmission would be a defensive bite, which is exceedingly rare.
Risk Severity
Extremely Low / Negligible. This spider is considered harmless to humans. There are no verified medical records of a bite causing significant symptoms.
Economic Impact
Treatment Costs
Professional Treatment
$200-$450 as part of a general spider treatment for a residential property.
Prevention Costs
$20-$50 annually for basic cleaning supplies and DIY insect sprays.
Diy Treatment
$15-$40 for a can of insecticide spray and a duster or vacuum.
Property Damage
Structural Damage
None. Their webs are superficial and do not damage surfaces.
Garden Damage
None. They are primarily an indoor species.
Food Contamination
None.
Equipment Damage
Can build webs inside stored electronics or equipment, but this is unlikely to cause damage.
Business Impact
Restaurant Issues
The presence of cobwebs can give a negative impression of cleanliness and hygiene to customers and health inspectors.
Retail Impact
Webs in changing rooms, stock rooms, or on shop floors can look unsightly.
Reputation Damage
For any business, particularly in hospitality or food service, visible cobwebs can lead to a perception of poor maintenance and damage reputation.
Operational Disruption
Minimal. May require brief closure of an area for cleaning.
Agricultural Impact
Crop Damage
None.
Yield Loss
None.
Beneficial Aspects
Inside the home, they provide a small but tangible benefit by preying on nuisance insects like ants and cockroaches.
Economic Loss
The main economic impact is the cost associated with aesthetic control – the labour and materials for cleaning and pest control treatments to maintain a clean appearance in homes and businesses.
Indirect Costs
Healthcare Costs
None. Their bites do not require medical treatment.
Cleanup Costs
The ongoing cost of labour and cleaning supplies to remove their persistent and messy webs from corners and cupboards.
Replacement Costs
None.
Preventive Maintenance
Costs related to regular pest control services or the purchase of DIY products to keep buildings web-free.
Detection & Signs
Visual Signs
- The presence of their messy, tangled cobwebs in dark corners.
- Sighting the spider itself, often hanging upside down in the web.
- Small, white, fluffy egg sacs suspended within the webs.
- An increase in the number of webs, especially in undisturbed areas.
- The spiders dropping to the floor and scurrying away when a light is turned on.
Physical Evidence
- The webs are the most obvious evidence. They are sticky and appear disorganised.
- Accumulation of dust and debris within old webs, making them more visible.
- Tiny carcasses of prey insects (like ants) entangled in the silk.
- The presence of tiny spider droppings (like small black pinpricks) on surfaces below the web.
- Shed spider skins (exuviae) may be found within the web.
Behavioral Signs
- Observing the spider dropping on a silk line when disturbed.
- Seeing a reduction in other crawling pests like ants in an area where these spiders are present.
- Small males may be seen wandering away from webs in search of mates.
- The rapid wrapping of any insect that falls into the web.
- Their sedentary nature means the presence of a web almost guarantees the spider is living there.
Seasonal Indicators
- In most indoor Australian environments, there are no strong seasonal indicators; they are present year-round.
- Population numbers might peak in late summer and autumn after a season of abundant food.
- A 'spring clean' of a home often reveals the extent of an infestation that built up over winter.
- In tropical regions, numbers may be highest during the wet season due to higher humidity and insect activity.
Early Warning Signals
- The appearance of one or two small, tangled webs in corners.
- Sighting a single spider in a cupboard or behind furniture.
- An increase in ant or small cockroach activity can be a predictor of a future increase in this predator.
- Because they reproduce quickly, a small number can become a large, unsightly infestation in a few months.
Prevention
Sanitation Measures
- Regularly vacuum and dust corners, behind furniture, and inside cupboards to remove spiders, webs, and egg sacs.
- Reduce clutter in storage areas, sheds, and garages to eliminate potential nesting sites.
- Control other insect pests like ants and cockroaches to reduce the spiders' food source.
- Keep kitchen areas clean and free of food scraps that attract prey insects.
- Promptly clean up spills and moisture sources.
Exclusion Methods
- Seal cracks and gaps in walls, floors, and around pipes to limit hiding spots.
- While primarily an indoor pest, ensuring windows and doors have tight-fitting screens can prevent prey insects from entering.
- Use door seals and weather stripping to block entry points from wall cavities or sub-floor areas.
- This spider is often carried in on items, so inspect second-hand furniture or stored boxes before bringing them inside.
- Seal gaps around skirting boards and architraves.
Landscaping Tips
- Keep vegetation and mulch away from the house foundation to reduce the number of insects (their food) living near the house.
- Ensure good drainage around the property to lower humidity levels.
- Store firewood and compost bins away from the house.
- These landscaping tips are more about reducing their food supply than controlling the spiders directly.
- Avoid creating damp, sheltered areas near entry points to the home.
Monitoring Strategies
- Regularly inspect dark and undisturbed areas like cupboards, basements, and garages for webs.
- Place sticky traps in out-of-the-way locations to monitor for crawling insects (their prey) and wandering male spiders.
- A simple visual check during routine house cleaning is the most effective monitoring strategy.
- Be mindful of webs reappearing in the same spots after being cleaned away.
- Professional pest inspections will identify conditions conducive to this and other pests.
Environmental Modification
- Use a dehumidifier in damp areas like basements or sub-floors to make the environment less hospitable.
- Improve ventilation in humid areas like bathrooms and laundries.
- Reducing clutter is the most effective environmental modification you can make.
- Adjusting indoor lighting does little to deter this species as they prefer dark corners anyway.
- Controlling their food source is a key environmental strategy.
Control Methods
Professional Treatment Methods
Chemical Control
A professional will apply a residual surface spray insecticide to corners, skirting boards, and other common harbourage areas. They may also use a space spray or aerosol to flush out spiders from hiding.
Biological Control
No effective biological control agents are used for this indoor pest.
Physical Control
Physical removal via vacuuming or brushing is a core part of any professional treatment, used to get rid of existing webs and egg sacs before spraying.
Integrated Approach
Integrated Pest Management (IPM) is the best strategy. It combines a thorough inspection, physical removal, targeted chemical application, and advice to the homeowner on sanitation and exclusion to prevent recurrence.
DIY Treatment Options
Natural Remedies
Sprays made with vinegar or essential oils (peppermint, tea tree) can act as a contact repellent but have very little residual effect and need to be reapplied constantly.
Home Made Traps
Sticky traps placed in corners can catch some spiders, but they are unlikely to solve an established infestation.
Deterrent Methods
The most effective deterrent is constant disturbance. Regularly cleaning and vacuuming an area will encourage the spiders to relocate.
Mechanical Control
Using a vacuum cleaner with a long hose attachment is the safest and most effective DIY method for removing spiders, webs, and egg sacs without getting close.
Treatment Effectiveness
Success Rate
Professional treatments have a very high success rate for controlling existing infestations and preventing new ones for several months. DIY methods can be effective if done diligently and repeatedly.
Timeframe
A professional spray provides immediate control and can remain effective for 6-12 months. DIY cleaning needs to be done weekly or bi-weekly to keep spiders at bay.
Follow Up Required
An annual professional spider treatment is usually sufficient for homes in high-risk climates.
Seasonal Considerations
Treatment can be carried out at any time of year for this indoor pest, as infestations are not strongly seasonal.
Application Techniques
- Targeted application of surface spray to known nesting sites.
- Crack and crevice treatment with an insecticidal dust or aerosol.
- A general broadcast spray along skirting boards and internal corners.
- Always follow product label instructions for safety and effectiveness.
Professional Services
Professional Treatment Services
Chemical Control
A professional will apply a residual surface spray insecticide to corners, skirting boards, and other common harbourage areas. They may also use a space spray or aerosol to flush out spiders from hiding.
Biological Control
No effective biological control agents are used for this indoor pest.
Physical Control
Physical removal via vacuuming or brushing is a core part of any professional treatment, used to get rid of existing webs and egg sacs before spraying.
Integrated Approach
Integrated Pest Management (IPM) is the best strategy. It combines a thorough inspection, physical removal, targeted chemical application, and advice to the homeowner on sanitation and exclusion to prevent recurrence.
Professional Treatment Costs
$200-$450 as part of a general spider treatment for a residential property.
Treatment Success Rates
Professional treatments have a very high success rate for controlling existing infestations and preventing new ones for several months. DIY methods can be effective if done diligently and repeatedly.
Treatment Timeframe
A professional spray provides immediate control and can remain effective for 6-12 months. DIY cleaning needs to be done weekly or bi-weekly to keep spiders at bay.
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Browse All ProvidersSeasonal Patterns
Spring Activity
In stable indoor environments, activity remains consistent. Spiderlings that survived cooler periods will grow rapidly as insect prey becomes more available.
Summer Activity
This is often the period of peak population growth, with warm temperatures accelerating development and reproduction. Webs and egg sacs become more numerous.
Autumn Activity
Populations are typically at their largest. Wandering males may be seen more frequently. This is a good time for a thorough clean-out before winter.
Winter Activity
In unheated spaces, activity and reproduction may slow down, but in heated homes, they can remain active throughout winter.
Breeding Season
Effectively year-round in the warm, stable conditions of an Australian home.
Peak Activity Period
Infestations often become most noticeable in late summer and autumn when populations have had months to build up.
Environmental Factors
Temperature Effects
Warm temperatures (22-30°C) are ideal and lead to the fastest life cycle completion. Cold temperatures are the main limiting factor on its geographical range.
Humidity Effects
They prefer moderate to high humidity, making them common in coastal Australian cities.
Photoperiod Effects
Day length has little impact as they are primarily indoor pests living in artificially lit or dark environments.
Weather Patterns
External weather has minimal effect on established indoor populations.
Legal Considerations
Pest Status
Considered a common domestic or nuisance pest.
Control Regulations
The use of pesticides for control is regulated by the Australian Pesticides and Veterinary Medicines Authority (APVMA). All products must be used according to label directions.
Professional Requirements
Pest control technicians applying chemical treatments in a commercial or residential capacity must hold a valid state-issued pest management license.
Environmental Considerations
When treating indoors, care must be taken to avoid contaminating food preparation surfaces, utensils, and fish tanks. Ensure adequate ventilation during and after application.
Compliance Requirements
- Following all safety and usage directions on the pesticide label is a legal requirement.
- Professionals must adhere to state-specific regulations for pest management.
- No special permits are needed to control this common spider.
- Proper storage of pesticides away from children and pets is essential.
- Disposal of empty containers must be done according to local council regulations.
Frequently Asked Questions
Is the Red-legged House Spider just another name for a Redback?
No, this is a common and important misconception. The Red-legged House Spider (*Nesticodes rufipes*) and the Redback spider (*Latrodectus hasselti*) are two completely different species. The Red-legged House Spider is harmless to humans. The easiest way to tell them apart is by looking at the abdomen. A Redback has a distinct, bright red or orange stripe (or hourglass on its underside) on a jet-black, globular abdomen. The Red-legged House Spider has a plain brown, globular abdomen with no prominent stripe at all. As its name suggests, its legs are also a noticeable reddish-brown colour. Misidentification causes unnecessary fear, so learning to spot the absence of the red stripe is key to correctly identifying this harmless indoor spider.
How dangerous is the Red-legged House Spider to humans?
The Red-legged House Spider is considered completely harmless and poses no danger to humans. Its fangs are tiny and may not even be capable of piercing human skin. There are no credible, verified records of its bite causing any significant medical issues. They are also extremely timid and non-aggressive; their instinct when threatened is always to flee, often by dropping from their web and hiding. The only potential health concern they pose is indirect: their messy, dusty webs can contribute to household allergens, which may affect individuals with pre-existing respiratory conditions like asthma. The spider itself, however, presents no venomous threat to people or pets.
What is the most effective way to get rid of Red-legged House Spiders?
The most effective way to get rid of them combines physical removal with preventative measures. Start with a vacuum cleaner. Use a hose attachment to thoroughly remove all visible spiders, webs, and any small, white egg sacs from corners, behind furniture, and inside cupboards. This provides immediate control. To prevent them from re-establishing, focus on sanitation and exclusion. Reduce clutter, control other household pests (their food source) like ants, and seal any cracks or holes that could serve as hiding spots. For persistent infestations, a DIY surface spray applied to corners and skirting boards can be effective, or a professional pest control treatment will provide a longer-lasting residual barrier for comprehensive control.
How can I prevent Red-legged House Spiders from returning?
Long-term prevention relies on making your home inhospitable to them. The single most important strategy is regular, thorough cleaning. Frequently vacuuming and dusting in dark, undisturbed areas like behind and under furniture, in closets, and along ceiling and floor junctions removes not only the spiders but also the webs and egg sacs they need to thrive. Secondly, manage their food supply. Keep your home free of other crawling insects like ants and cockroaches by maintaining good kitchen hygiene. Finally, reduce humidity in damp areas like bathrooms and basements with better ventilation or a dehumidifier. By consistently removing their webs and reducing their food and preferred humid conditions, you make your home a much less attractive place for them to live.
Why do these spiders only seem to live in certain parts of my house?
Red-legged House Spiders are very specific about their habitat, which is why you find them concentrated in particular spots. They have three main requirements: darkness, lack of disturbance, and the right structure for a web. They thrive in dark corners where they are less visible to predators and people. They need areas that are infrequently disturbed, which is why they are common in the back of cupboards, in basements, under heavy furniture, and in sheds. Finally, they need a three-dimensional space, like a corner, to build their tangled web. A flat, open wall is not suitable. These factors combined mean you will almost always find them clustered in the quiet, dark, forgotten corners of your home.
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