Quick Facts About Cellar Spiders You Should Know

Cellar spiders are one of the most common yet often misunderstood arachnids found in homes around the world. Despite their somewhat spooky appearance and reputation, these spiders play a unique role in our ecosystems and even within our homes. This article covers quick facts about cellar spiders, shedding light on their behavior, biology, and importance.

What Are Cellar Spiders?

Cellar spiders belong to the family Pholcidae, commonly referred to as “daddy long-legs” in many English-speaking regions (although this name can also refer to harvestmen or crane flies, which are entirely different creatures). These spiders are known for their extremely long, slender legs and small bodies. They typically dwell in dark, damp environments such as basements, cellars, caves, and corners of rooms.

Physical Characteristics

Body Size: The body length ranges from 2 to 10 millimeters.

Leg Span: Their legs can be several times longer than their body, sometimes reaching lengths of 50 millimeters or more.
Color: Usually pale gray or tan with subtle markings.
Eyes: They have eight small eyes arranged in two groups.

Their fragile appearance often leads to misunderstandings about their capabilities and danger levels.

Habitat and Distribution

Cellar spiders are cosmopolitan, meaning they are found almost everywhere on Earth except for extremely cold regions like Antarctica. Their preferred habitat tends to be sheltered, humid areas:

Basements

Cellars
Crawl spaces
Under rocks or logs outdoors

Inside caves

They adapt well to human environments because these locations provide protection from predators and stable humidity levels.

Behavior and Web Structure

One of the defining features of cellar spiders is their web-building behavior. Unlike orb-weavers that create circular webs, cellar spiders build messy, irregular webs that look like tangled sheets or cobwebs. These webs usually occupy corners of ceilings or walls.

Web Purpose

The primary purpose of their webs is to catch prey. However, unlike other spiders whose webs act as strict traps, cellar spider webs serve more as a detection system. When prey gets tangled in the web, the spider vibrates it rapidly to confuse the insect before attacking.

Unique Hunting Technique

Cellar spiders exhibit a fascinating behavior called “whirling.” When disturbed or threatened by predators or humans, they rapidly spin in their tangled webs. This spinning motion makes them appear blurry and hard to catch or identify.

Diet: What Do Cellar Spiders Eat?

Cellar spiders primarily feed on small insects and other arthropods caught in their webs. Their diet typically includes:

Mosquitoes
Flies
Moths

Small beetles
Other small spiders (including dangerous ones)

In fact, cellar spiders have been known to prey on venomous spiders such as black widows by immobilizing them with their long legs before injecting venom. This predatory behavior makes them beneficial natural pest controllers within homes.

Are Cellar Spiders Dangerous to Humans?

One common myth is that cellar spiders are highly venomous but cannot bite humans due to short fangs. This is completely false.

Venom Toxicity

Cellar spider venom is not dangerous to humans. While all spiders have venom to subdue prey, the venom of cellar spiders is considered harmless to people. Their fangs are capable of biting but their bites rarely penetrate human skin effectively.

Bites and Symptoms

Bites from cellar spiders are very rare because they tend to avoid humans and generally lack aggression. If bitten accidentally:

The bite site may show minor redness.
Mild irritation might occur.
No serious allergic reactions have been documented.

In summary: cellar spiders do not pose any health risks.

Reproduction and Life Cycle

Like most spiders, cellar spiders reproduce sexually. The female lays eggs inside a silken sac attached to her web.

Egg Sac Details

Contains between 20 to 50 eggs.

Female guards the sac until spiderlings emerge.

Once hatched, baby spiders disperse by ballooning — releasing silk threads that catch the wind and carry them away to new locations.

Lifespan

The average lifespan of cellar spiders can range from 1 to 2 years depending on environmental conditions and predation pressures.

Interesting Adaptations

Several remarkable adaptations help cellar spiders survive:

Extremely Long Legs: Help them feel vibrations over large distances on their web.
Whirling Defense Mechanism: Effective against predators.

Ability to Eat Other Spiders: Including venomous ones.
Low Metabolism: Allows survival during prolonged food shortages.

These adaptations make cellar spiders resilient and efficient hunters despite their delicate appearance.

Common Misconceptions About Cellar Spiders

Myth #1: They Are Extremely Venomous but Can’t Bite Humans

This myth likely arose because some people confuse cellar spiders with other “daddy long-leg” species that differ taxonomically. Scientific evidence shows that cellar spider venom is weak and they can bite but rarely do so with harmful effects.

Myth #2: They Are Harmful Pests That Should Be Killed

In reality, cellar spiders help control populations of annoying insects like mosquitoes and flies inside homes without causing damage themselves. Many pest experts recommend leaving them alone unless infestations become overwhelming.

Myth #3: They Build Neat Spider Webs Like Orb Weavers

Cellar spider webs appear messy but serve important functional roles for trapping prey effectively in low-light environments where neat webs would be less effective.

How To Manage Cellar Spider Populations Indoors

While cellar spiders are generally harmless and beneficial indoors, some people prefer limiting their numbers for aesthetic reasons or due to phobias.

Tips for Managing Them:

Reduce Humidity: Use dehumidifiers in basements or cellars since they prefer moist environments.
Regular Cleaning: Vacuum webs regularly from corners and ceilings.

Seal Entry Points: Close gaps around windows/doors where insects might enter.
Limit Food Sources: Control other insect populations that attract them.

Chemical pesticides are rarely necessary unless infestations are severe because they may harm beneficial insects too.

Conclusion: Why Cellar Spiders Are Worth Knowing About

Cellar spiders may not win any beauty contests with their spindly legs and messy webs, but they play an important ecological role both outdoors and indoors by controlling insect populations naturally. Understanding these quick facts about cellar spiders helps dispel myths and appreciate them as harmless neighbors rather than pests.

Next time you spot one dangling quietly in a dark corner of your basement or cellar, remember these gentle creatures contribute more than you might expect toward keeping your home’s ecosystem balanced — all while rarely bothering you at all.