Are Cellar Spiders Dangerous? Behavior, Facts & FAQ

Cellar Spiders, commonly referred to as “Daddy Long Leg” spiders, are long-bodied brown spiders that have super-thin legs. Common throughout the United States, these narrow-bodied spiders are about a third of an inch long, but their legs can be up to 2 1/2 inches in length. They have eight eyes and are known for creating cob-like webs in basements, attics, and crawl space areas. But are these spiders dangerous? These intimidating spiders aren’t a real threat to humans and usually eat other spiders and small insects.

The Verdict

Despite how scary they may look, cellar spiders aren’t dangerous, though large webs of cellar spiders can be difficult and annoying to remove. Although cellar spiders can bite, their mouths are too weak for them to penetrate human skin and inject venom (though it paralyzes their small prey).

Cellar spiders love to lurk in dark areas that are rarely disturbed — which is why they’re commonly seen in home basements. These particular spiders are difficult to control with traditional insecticides because they don’t move as much as insects and other spiders, so they won’t always walk through residual insecticides.

How To Get Rid of Cellar Spiders

A vacuum attachment with a hose attachment is one of the best options for controlling cellar spiders. To get rid of them, run the vacuum through your home, removing all cobwebs and spraying any live spiders with insecticide.

This process should be repeated every few weeks until you no longer see any new webs. You can also use poisonous traps to lure them and kill them before they lay more eggs.

Cellar Spider Behavior

Cellar spiders become almost acrobat-like when they’re threatened by touching their web, or when their prey is too big for comfort. They’re often referred to as the “Vibrating Spider”, because they’ll spin around rapidly in their web.

This movement makes it more difficult for predators to locate the spider, and it can also increase the chances of the spider capturing those insects who have just touched their web and are still near enough to feast on.

The spider will either retreat to a corner or fall from its web if it’s being harassed. These long spiders will hang upside down in a messy, tangled web for hours on end. They usually only move around to get food or find new areas to create a web if their current one was disturbed or destroyed.

Cellar Spider Infestation

Cellar spiders can be found in all temperatures throughout the year. The females lay eggs in groups of anywhere from 25 to 60 and then wrap them in silk for protection. As she hangs the eggs from her web, she’ll protect them and hold on to them, carrying them on her back.

It can take up to one year for the eggs to mature after they hatch. These spiders can survive for about two more years if they are in good health and have regular food access.

Ways To Keep Cellar Spiders Out of Your Basement

These eight-legged insects are attracted to basements that are damp, dark, cluttered, or that are rarely visited by humans. And if left unchecked, and under the right conditions, they can become a nuisance of an infestation. Here are a few ways to prevent them from taking over your basement or crawl space.

Keep Some Lights On

Even battery-operated LED lights can help. Because these spiders are natural introverts and prefer solitude, it’s best to deprive them of what they love the most — darkness. Installing LED lights in an underground room or basement can temporarily discourage these spiders from nesting, hunting, mating, and spinning webs, as they fear being caught by other predators.

Also, LED lights are usually brighter and more affordable than regular halogen lamps. There are tons of affordable LED lights on Amazon and at Home Depot (or Lowes). This can help keep these pests away and force them to find a new home.

Get Rid of Basement Clutter And Dirt

Cellar spiders use clutter to protect themselves from other predators. Clutter and busy areas also provide a safe space for female spiders to create cobwebs and feed. These webs are used by the insects to trap prey and travel to protect or encase their eggs and young spiderlings.

So, try to keep your basement as clean as possible by getting rid of excess belongings, boxing loose items such as clothes or building materials, and keeping the area free of large piles of objects (such as firewood, boxes, old furniture, garden supplies, etc.).

Diligently Vacuum Cobwebs

If you have a cellar spider infestation, the quicker you get rid of it the better. First, be sure to go around the entire basement and vacuum each and every cobweb that you see. Try to do this every day, to prevent the female from forming new cobwebs and places to nest.

Be sure to get all cracks, crevices, and between any furniture. Essentially, you want to vacuum all the places that are the most inaccessible and less visible in the basement.

Get Rid of Moisture

Basements are known for being cooler and having high humidity than other floor levels. This environment is perfect for spiders. If possible, purchase a dehumidifier for your basement so that it’s no more than 55% humidity in the space. This will also discourage the growth of mold and mildew. Be sure to check for any signs of water leaks, pooling, drainage problems, or other issues that may cause dampness in the basement.

Seal Cracks and Holes

Caulk can also be used to seal cracks and crevices on basement walls and floors. These cracks and crevices are easy entry points for all kinds of household insects, including cellar spiders. You’ll be surprised by just how little space they need to enter your home. Be sure to caulk around window and door openings as well.

Wrapping Things Up

Cellar spiders can be intimidating to look at, but they’re relatively harmless. However, you don’t want an infestation to get out of control so be sure to take measures to mitigate them as soon as you spot one.

You can use traditional insecticides, as well as vacuum their webs to keep them from nesting. And to prevent these spiders from making your basement their new home, be sure to seal any cracks and holes in your basement and keep it clean and clutter-free.

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Featured Image Credit: Cassandra Madsen, Shutterstock