Why Do Spiders Keep Coming Back in the House

Spiders might be mostly beneficial bugs you actually want around your home because they feed on small insects, but they invoke fear in some people. Studies suggest arachnophobia affects up to 6% of the world’s population. If arachnids give you the ick, understanding what attracts spiders to houses can help you take steps to reduce their numbers.

“If people are seeing large amounts of spiders around their home, it usually means they have conditions that support large numbers of the prey they consume, namely other insect species,” Craig Sansig, Associate Certified Entomologist, says.

I spoke to three professional entomologists to find out how to keep home spider numbers down and why seeing a few scuttling around doesn’t need to be panic-inducing.

What Do Spiders Eat?

Spiders dine on a range of insects and other arachnid species. If you don’t kill spiders, they can help rid your house of mosquitoes, flies, fleas, ants and other pesky bugs.

What Attracts Spiders?

While a banquet of bugs is what most attracts spiders to houses, they’re more likely to stick around if you provide easy access and cozy hiding spots (or, in other words, dark, quiet spots that are rarely disturbed).

How to Prevent Spiders in My Home

You can’t keep spiders out of your home entirely, but there are steps you can take to manage their numbers.

Implement exclusion techniques

Associate Certified Entomologist Shannon Harlow-Ellis suggests prioritizing sealing gaps around windows, doors, and utility line penetrations. This will help exclude spiders and other insects (their food) from your house.

Regular cleaning and clutter removal

A clean and clutter-free property is less attractive to spiders and the critters they eat, and it makes it easier for you to spot them.

• “Regularly sweep and vacuum corners, behind doors, and around clutter to pick up spiders, webs, and egg sacs,” Santos Portugal, an Assistant Extension Professor of Urban Entomology at Mississippi State University, says.
• Sansig suggests trimming trees and shrubs away from the home to allow airflow and decrease insect habitat.
• Many spiders prefer dark, quiet spots with minimal airflow. “Eliminating debris piles [leaves, wood, etc.] and old, unused items will help to limit conducive habitat, especially outdoors and in crawl areas of homes,” Sansig says.

Reduce exterior night lighting

Bright exterior lights draw in flying insects that make tasty meals for spiders. Santos recommends the following:

• Don’t leave porch lights on all night.
• Close curtains at night when you have lights on.
• Consider using motion-activated exterior lights instead of floodlights remaining on all night.

It’s also possible to buy yellow or sodium vapor bulbs, which are less attractive to insects than conventional cool blue bulbs.

Control moisture levels

Damp conditions attract insects that spiders eat, especially during hot, dry summers. Fix dripping water spigots, clean gutters, and turn downspouts outward to prevent pooling water near your home.

Apply pesticides

Pesticides can help control spider populations. Sansig says they succumb easily when contacted by most products labeled for use on spiders in and around the home. “Pesticides may also help to eliminate the species of insects they prey upon,” he says. Spider repellents containing ingredients such as deltamethrin (DeltaDust®), bifenthrin or cyfluthrin (Tempo®) are effective.

Typically, they’re applied to cracks and crevices in baseboards and windows and in crawl spaces, basements and attics. Sansig advises carefully following all label directions when using these products.

Regular application is necessary if pesticides are used as a barrier spray around your home’s perimeter or when treating the areas where the spiders are actively living. Making your home less attractive through exclusion and habitat modification is typically a more effective and environmentally friendly long-term strategy.

Why Do Spiders Keep Coming Back?

Even if you’re rigorous about implementing preventative measures, preventing more spiders from returning to your home is virtually impossible. However, the numbers should be manageable.

If you continue to see large numbers of spiders, you may need help eliminating an infestation of insects that spiders love to eat, or maybe you didn’t find a spider’s hidden nesting spot, and now hundreds of eggs have hatched.

When to Call a Pro

Hiring a professional to help with spider control can reduce stress levels if DIY solutions aren’t working, you’re not sure what type of spiders you’re dealing with, or your arachnophobia is severe. Harlow-Ellis says this is especially true if you have known allergies to spider bites.

FAQ

Are spiders dangerous?

Some spider species are dangerous because of their more venomous bites. However, most are harmless and help balance our ecosystem by preying upon problematic pests. “Even the most venomous of spiders in the U.S. actually pose little risk to people,” Sansig says. Black widow and brown recluse spiders, for example, hide away from humans and don’t bite unless threatened. When they do bite, it’s rarely serious, although it can require medical attention. “Statistically, you’re actually more likely to be hit and killed by a falling manhole cover while walking in NYC than from a spider bite,” Sansig says.

How long do spiders live?

Most common spider species live less than a year. Some can live for several years, and a few, such as tarantulas, can live for over 20 years. However, males typically die soon after they mate, and even females often become prey for other animals before they reach old age.

How often do spiders lay eggs (and how many)?

“The brown recluse lays between 1 and 5 egg sacks over a two-year period, each containing 40 to 50 eggs,” Sansig says. “The black widow has larger egg sacs with an average of about 250 eggs per egg sac.” He explains that mortality is high among developing spiderlings, and most don’t survive to adulthood.

Where do spiders lay eggs?

Female spiders often carry their egg sac with them until the spiderlings hatch, although some attach their sacs to webs or tuck them away in a well-hidden spot. That’s why a clutter-free, well-vacuumed home can help to control spider numbers.

About the Experts

• Shannon Harlow-Ellis is an Associate Certified Entomologist and Technical Services Manager at Mosquito Joe, a Neighborly company; email interview, Jul. 16, 2024.
• Santos Portugal is an Assistant Extension Professor of Urban Entomology at Mississippi State University; email interview’ Jul. 17, 2024.
• Craig Sansig is an Associate Certified Entomologist and Public Health Entomologist and Service Director of Viking Pest Control; email interview, Jul. 19, 2024.

Sources

• Polák J, Sedláčková K, Janovcová M, et al. Measuring fear evoked by the scariest animal: czech versions of the spider questionnaire and spider phobia beliefs questionnaire. BMC Psychiatry. 2022;22:18.