Common House Spider
Parasteatoda tepidariorum
Anatomy
Identification
Distinguishing Features
- Bulbous abdomen with mottled brown pattern, larger than cephalothorax
- Builds messy, three-dimensional 'tangle webs' (not geometric orb webs)
- Long, thin legs with faint dark rings, no obvious spines
- Eight eyes in two rows
- Completely harmless to humans—no medically significant bite
Similar Species
- Brown Recluses do NOT exist in Canada. House Spiders are sometimes mistaken for them due to similar brown coloration, but they lack the characteristic violin marking on the cephalothorax and have a distinctly bulbous abdomen. There are no medically significant spiders established in most of Canada.
- Larger spider (up to 18mm) with sheet-like webs featuring a funnel retreat in one corner. Also completely harmless. House Spider webs are chaotic 3D tangles, not flat sheets with funnel retreats.
Biology
Lifecycle
Females live 1+ year, males shorter. Egg sacs contain 150-400 eggs. Multiple sacs per female.
Diet
Effective pest controllers—preys on house flies, mosquitoes, ants, and even other spiders. A single house spider can consume hundreds of insects per year.
Nesting
Builds irregular, chaotic 3D 'tangle webs' in corners, window frames, and undisturbed storage areas. If a web doesn't yield food, they abandon it and build another elsewhere—leading to the accumulation of 'cobwebs' in neglected corners. Female remains in or near the web.
Signs of Infestation
Cobwebs in corners
Irregular, tangled webs accumulating in ceiling corners and window frames.
Spider visible in web
Small brown spider hanging inverted in the center of the web.
Egg sacs in web
Tan, papery spheres (5-9mm) suspended in the web structure.
Insect remains in web
Wrapped prey items and debris caught in sticky threads.
Where They Nest
- Ceiling corners in all rooms
- Window and door frames
- Basements and garages
- Closets and storage areas
- Behind furniture
Distribution in Canada
Found in buildings across Canada. Synanthropic—thrives in human structures.
Active Season
Active year-round indoors. Web-building visible when cleaning is infrequent.
House Types at Risk
This pest is commonly found in these home types
Bungalow / Ranch
Moderate RiskBasements and garages provide undisturbed web-building locations. Prey insects common at grade level.
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Two-Story
Moderate RiskHigh ceilings and upper corners provide protected web sites often missed during cleaning.
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Crawlspace Foundation
Moderate RiskCrawlspace harbours many spider species. They may enter living space seeking prey.
View house details →Prevention
- Regular vacuuming of corners and ceilings
- Remove webs promptly to discourage re-establishment
- Reduce insect prey by sealing entry points
- Use yellow exterior lighting (attracts fewer insects)
- Declutter storage areas
Professional Treatment
Rarely needed for house spiders. Residual perimeter treatments reduce populations if numbers are excessive. Focus on prey reduction.
Get Spider Control ServiceFrequently Asked Questions
What does a Common House Spider eat?
Effective pest controllers—preys on house flies, mosquitoes, ants, and even other spiders. A single house spider can consume hundreds of insects per year.
Where does a Common House Spider nest?
Builds irregular, chaotic 3D 'tangle webs' in corners, window frames, and undisturbed storage areas. If a web doesn't yield food, they abandon it and build another elsewhere—leading to the accumulation of 'cobwebs' in neglected corners. Female remains in or near the web.
When is a Common House Spider most active?
Active year-round indoors. Web-building visible when cleaning is infrequent.
What are the signs of a Common House Spider infestation?
Cobwebs in corners: Irregular, tangled webs accumulating in ceiling corners and window frames. Spider visible in web: Small brown spider hanging inverted in the center of the web. Egg sacs in web: Tan, papery spheres (5-9mm) suspended in the web structure. Insect remains in web: Wrapped prey items and debris caught in sticky threads.
How can I prevent a Common House Spider infestation?
Regular vacuuming of corners and ceilings. Remove webs promptly to discourage re-establishment. Reduce insect prey by sealing entry points. Use yellow exterior lighting (attracts fewer insects). Declutter storage areas.
How is a Common House Spider treated?
Rarely needed for house spiders. Residual perimeter treatments reduce populations if numbers are excessive. Focus on prey reduction.
Scientific Classification
- Kingdom
- Animalia
- Phylum
- Arthropoda
- Class
- Arachnida
- Order
- Araneae
- Family
- Theridiidae
- Genus
- Parasteatoda