If you have noticed a large number of spindly, spider-like creatures in the corners of your basement, garage, or other infrequently used rooms, you are likely seeing cellar spiders. Cellar spiders, sometimes called daddy long-legs spiders, are extremely common household pests that tend to thrive in dark, damp locations in homes. If you seem to have an overabundance of cellar spiders, there are a few key reasons why they may be so prevalent in your home.
Page Contents
- 1 What Are Cellar Spiders?
- 2 Why Are Cellar Spiders in My House?
- 3 Why Are There So Many Cellar Spiders?
- 4 How to Get Rid of Cellar Spiders
- 4.1 Remove Their Webs and Egg Sacs
- 4.2 Use Insecticides
- 4.3 Utilize Traps
- 4.4 Improve Lighting
- 4.5 Reduce Humidity
- 4.6 Seal Possible Entry Points
- 4.7 Clean and Organize Infrequently Used Rooms
- 4.8 Remove Excess Water Sources
- 4.9 Remove Indoor Plants
- 4.10 Use Desiccant Dusts
- 4.11 Apply Repellents
- 4.12 Encourage Predatory Spiders
- 4.13 Use Natural Predators
- 4.14 Contact a Pest Control Professional
- 5 Preventing Future Cellar Spider Infestations
- 6 Conclusion
What Are Cellar Spiders?
Cellar spiders belong to the pholcid spider family and get their common name from their tendency to live in dark, humid cellar areas in homes. There are many different species of cellar spiders, but some of the most common in North American homes include:
- Cross spider – Pholcus phalangioides
- Domestic cellar spider – Psilochorus pullulus
- Southern cellar spider – Holocnemus pluchei
- Longbodied cellar spider – Psilochorus simoni
These spiders are very thin and gangly, with small bodies and exceptionally long, thin legs that can span up to 2.5 inches tip to tip. Their legspan allows them to build large, irregular webs in corners of rooms in order to snare prey. Cellar spiders tend to be pale tan to light brown in color, and they have a distinctive globe-shaped abdomen.
Why Are Cellar Spiders in My House?
Cellar spiders thrive in human homes because these environments provide ideal conditions for them. Homes tend to be warmer than outdoors, and cellar spiders prefer temperatures between 65-80°F. They gravitate towards basements, crawl spaces, garages and storage sheds because these areas are generally cooler and more humid than other parts of the home.
Cellar spiders also build their messy, chaotic webs in corners of unused rooms because they can avoid being disturbed. The still air in these neglected areas allows their webs to remain intact for long periods. Homes also provide a bounty of insects for cellar spiders to prey on, including mosquitoes, flies, ants, cockroaches, moths and more.
Common Cellar Spider Entry Points
Cellar spiders can find their way into homes through a few key entry points:
- Cracks or gaps around windows, doors, foundation, pipes or wiring
- Openings in torn window screens
- Through vents or ductwork
- Through cracks in a home’s foundation
- Hitchhiking indoors on items like firewood, cardboard boxes or potted plants
Why Are There So Many Cellar Spiders?
While a few cellar spiders here and there are normal, a large infestation indicates conditions that are highly favorable to them inside your home. Here are some reasons why cellar spider populations can get out of hand:
Lack of Cleaning or Use of Infrequently Visited Rooms
Cellar spiders prefer to build webs in neglected, infrequently used rooms like basements, attics, crawl spaces, garages and sheds. When these areas are not cleaned regularly, there are more cobwebs and insect prey to draw in more spiders. Simple maintenance like vacuuming, cleaning and organizing these spaces makes them less hospitable to cellar spider infestations.
Plentiful Access to Food and Water
Cellar spiders thrive when there are plenty of insects for them to eat. Homes with ongoing issues with pests like mosquitoes, flies, cockroaches, ants and crickets will be more attractive to cellar spiders. Food spills, open pet food bags and excess moisture from leaks or condensation also draw in insect prey. Removing food sources and fixing leaks will discourage cellar spiders.
Lack of Repairs
Structural deficiencies like cracks, gaps and openings throughout the home provide easy access for cellar spiders to get inside. Repairing any cracks in your foundation, sealing openings around windows and doors, and patching holes will eliminate common spider entry points.
Clutter
Cellar spiders love dark, cramped spaces to build their webs. Rooms overflowing with stored items and clutter give them plenty of spots to hide and nest unbothered. Getting rid of unnecessary clutter reduces areas for webs to be built.
Incorrect Lighting
Cellar spiders avoid bright lights, so having proper lighting in infrequently used rooms helps make them less welcoming. Replace burned out light bulbs and add additional lighting sources if needed.
Lack of Competition from Other Spiders
Cellar spiders flourish in the absence of competing spider species like black widows and brown recluse spiders. Having a diversity of spider species prevents any one type from dominating. Removing cellar spider webs may allow web space for spiders that prey on cellar spiders.
Ideal Environment
Cellar spiders are very well adapted to the conditions in many homes. The warmth, humidity, shelter, prey availability and seclusion found in attics, basements and sheds create an ideal habitat for them to thrive.
How to Get Rid of Cellar Spiders
If you have identified excess cellar spiders as the cause of overabundant spider webs in your home, there are several steps you can take to eliminate them:
Remove Their Webs and Egg Sacs
Use a broom or vacuum with a hose attachment to remove all existing webs and any white, silken egg sacs where cellar spiders may have laid their eggs. This helps eliminate current spiders and prevents future generations.
Use Insecticides
Apply residual insecticide sprays containing ingredients like lambda-cyhalothrin, gamma-cyhalothrin or deltamethrin. Direct sprays into corners, along baseboards and ceilings, and behind stored items where webs may be hidden. This will kill any spiders that walk through treated areas.
Utilize Traps
Glue boards and spider traps can help catch wandering cellar spiders. Place traps along walls, in corners, or areas where you frequently see webs. Traps will need to be cleaned out and replaced regularly to remain effective.
Improve Lighting
Increase lighting by replacing bulbs, removing fabric coverings from windows to brighten rooms, and keeping lights on for longer. Cellar spiders avoid well-lit areas.
Reduce Humidity
Use exhaust fans, ventilate attics and basements, and use dehumidifiers to keep humidity under 50%. Lower humidity makes conditions less favorable for cellar spiders.
Seal Possible Entry Points
Seal any openings where spiders could get in like cracks in the foundation, gaps around windows and doors, openings around pipes or wiring, and torn window screens. This will help block them from entering your home.
Clean and Organize Infrequently Used Rooms
Vacuum, sweep away webs, and keep rooms free of dust. Remove clutter and cardboard boxes that provide shelter for cellar spiders. Keeping areas clean and tidy leaves fewer places for them to hide.
Remove Excess Water Sources
Fix any leaks or dripping pipes that provide moisture, and promptly clean up any spills or standing water. Eliminate spider access to open pet food and water bowls.
Remove Indoor Plants
Houseplants provide humidity, shade and habitat for insects that could attract spiders. Consider removing excessive indoor plants to reduce appealing conditions.
Use Desiccant Dusts
Sprinkle diatomaceous earth, fossilized silica powder, silica aerogel or other desiccant dusts into spider-prone areas. The dusts will dry and kill spiders upon contact.
Apply Repellents
Natural spider repellents like citronella, lavender, peppermint or vinegar can be applied around baseboards, windows and doorways. These strong scents may deter spider activity.
Encourage Predatory Spiders
Let non-web building spiders like jumping spiders, wolf spiders and lynx spiders take up residence to prey on cellar spiders and compete for food sources.
Use Natural Predators
Cellar spiders can be preyed upon by lizards like geckos or anoles, as well as wasps, centipedes and ants. Introducing these natural enemies may help control populations.
Contact a Pest Control Professional
For severe cellar spider infestations, contact a licensed pest control company. Professionals have access to stronger insecticides and methods to treat your entire home.
Preventing Future Cellar Spider Infestations
After eliminating existing cellar spiders, you will need to take proactive steps to discourage future ones from moving back in:
- Seal any cracks, holes or openings in your home’s interior and exterior.
- Install weather stripping around doors and windows.
- Keep windows and doors closed, where possible.
- Use screens in windows, doors, and vents.
- Reduce clutter and storage, especially cardboard, in problem areas.
- Clean gutters and direct water away from your home’s foundation.
- Maintain low humidity through ventilation and dehumidification.
- Fix any indoor water leaks immediately.
- Clean infrequently used rooms regularly.
- Keep crawl spaces and attics well insulated.
- Remove indoor plants that encourage insects.
- Install yellow lighting which attracts fewer insects.
- Keep tree branches, bushes, and plants trimmed back from touching your home.
Conclusion
Having an overabundance of nuisance cellar spiders is a common problem in homes that provide ideal habitat conditions for these pests. By identifying and modifying factors that allow them to thrive such as access, food, water, clutter and neglected spaces, you can eliminate current spider infestations. Ongoing prevention measures will also discourage future cellar spiders from re-colonizing your home after it has been cleared of them.
With diligence and persistence taking away cellar spider necessities like insects, shelter and humidity, you can successfully get rid of cellar spider invasions and maintain a home environment less welcoming to them.
