House spider can refer to a specific spider such as the American House Spider or refer to any spider that is likely to be encountered inside of the home. Either way you look at it, most spiders found in homes including the ones with house spider in their name are not dangerous.

Percentage of spiders that are actually dangerous. 

Out of over 37,000 species of spiders described worldwide, less than 30 of them are medically significant. From a percentage standpoint, this represents less than 1/10 of one percent.

Dangerous – These spiders have a venom that is strong enough to impact bitten people:

  • Violin (Loxosceles) Spiders – Also known as fiddleback spiders, the brown recluse is native to the United States and other non-native species have been introduced as well.
  • Hourglass Spiders/Widows– These are a subset of cobweb spiders including the Southern Black Widow, the brown widow, western black widow, and the northern widow known to have a neurotoxic venom that can cause problems in humans.
  • False Black Widows– These are closely related to the Hourglass spiders, but their venom is less potent and has a less significant impact.

Not Dangerous – These spiders receive numerous inquiries due to their ugliness, speed, size, or their nature as a hunting spider. They are not likely to bite people. If they do bite, the bite will be painful, but is not considered dangerous.

  • Cobweb Spiders– Often confused for the closely related widow spiders, these spiders include the American house spider and the Northern Cobweb spider. They spin irregular webs in places that annoy people, but their venom is usually not dangerous
  • Garden Spiders– As the name implies, they are typically found in gardens. Since they are large and colorful, they instill fear, but their venom is usually not dangerous.
  • Wolf Spiders– Since they are true hunters, they are fast and aggressive though usually not toward people. Their movement combined with their size and hairiness make them one of the most feared invasive spiders, but their venom is not usually dangerous to humans.

In addition to the spiders that are considered dangerous because of the ability of their venom to impact human health, there are spiders that carry a secondary risk. Some spiders such as sac spiders or woodlouse hunters carry the possibility of secondary bacterial infections from bites.

What areas of the United States are dangerous spiders found in?

The recluse spiders populate 15 states including:

  • Alabama
  • Arkansas
  • Georgia
  • Illinois
  • Indiana
  • Iowa
  • Kansas
  • Kentucky
  • Louisiana
  • Mississippi
  • Missouri
  • Ohio
  • Oklahoma
  • Tennessee
  • Texas

Widow spiders of one type or another populate the different regions of the united states.

The false black widow spider lives in the following regions:

  • Atlantic Coastal Region
  • Gulf Region
  • Pacific Region

Where did dangerous spiders originate from? 

The brown recluse is native to the US. The brown widow was thought to originate in South Africa, but it is possibly native to South America as well. The false widow originated in Madeira and the Canary islands where it supposedly spread to England.

Why do certain spiders choose to live in certain regions? 

A spider’s choice of living arrangements is largely dependent upon its food source. Some spiders rely on food sources related to high humidity or plentiful water, but other spiders can live in very arid climates and extract the hydration they need from their prey. They are versatile creatures and have adapted to worldwide conditions.

Spiders frequently migrate to new areas along with people shipping goods around the world. In the case of the Chilean recluse spider, it was introduced to Los Angeles County and became established, but has not shown signs of spreading. If a spider is introduced to a habitat it is adapted for, it will survive and likely flourish. If not, it will be limited and possibly die off from that area.

Hunting spiders vs web building spiders 

Surprisingly too many, not all spiders spin their web in the corner of a barn and hang out with the local farm animals. There are three different kinds of hunters in the arachnid world:

  • Web catchers – These spiders spin webs where insects will traffic in order to capture them directly. Orb weavers spin elaborate, ornate webs. Similar to the orb weavers, cobweb and hourglass spiders spin a messy and erratic web.
  • Combo catchers – These spiders don’t rely heavily on their webs like the web catchers. They will spin a few strands near their hiding spot to signal when its prey is passing within reach and trip up or snag said prey for an easier catch. Woodlouse hunters are an example of this kind of web hunter.
  • True hunters – These spiders actively hunt for prey on the ground and will rest beneath debris, stones, etc. when not hunting. The wolf spider is a true hunter and will even carry it’s hatchlings on its back until they are old enough to fend for themselves.

Where should I check for them inside of my house? 

The most common ways that the violin spiders get carried into homes are on:

  • boxes
  • furniture
  • rolled carpets

They can be carried into the home anytime of year, so inspect those and similar items whenever bringing them inside a structure.

Once they are in the home, they will gravitate to and rest in:

  • attics
  • crawl spaces
  • basements
  • wall voids
  • upholstered furniture
  • clothing
  • cardboard boxes
  • items stored in cardboard boxes

Widow spiders prefer more recessed corners of structures. They are likely to live in:

  • outbuildings
  • sheds
  • pump enclosures
  • meter enclosures
  • rodent bait stations
  • wood piles

Spiders prefer being in low traffic areas for people, however they need high traffic area for their preferred food. Some will gravitate towards light from exterior lighting or light coming out of large windows. Others will seek water sources that could either be direct water or humidity.

In addition, always consider an items storage location. It is always important to check things stored in:

  • basements
  • attics
  • garages
  • guest or other infrequently visited rooms
  • cellars
  • sheds
  • barns

for spiders that may have decided to rest inside of it or use it as their main home. Be cautious when reaching into:

  • gloves
  • helmets
  • boots
  • coats

or other items that may contain a lurking spider. A spider is smart enough to know that it will lose a fight with something hundreds of times its size, but if it is hanging out inside of a glove, it will choose fight over flight since it has nowhere to flee to.

What should I do to keep dangerous spiders out? 

Beyond choosing to live in a place with few dangerous spiders, follow the following 7 tips to keep spiders in check:

  • Reduce Clutter – Spiders like things they can hide in and under. Fewer places for hiding make it harder for spiders to subsist and even harder for their populations to expand.
  • Inspect transported items – Whether originating from a low traffic source on your property or brought in from off the property, inspecting an item will reduce the number of hitchhiking spiders. Spiders are not typically hard to find, so a quick visual check will yield great results. Keep in mind you want to inspect it before bringing the item into the home. The spider is more likely to run off during the inspection process than be found, so it is better for it to run off and live happily outside than run if into the home somewhere.
  • Reduce unnecessary moisture sources – While not all spiders need much moisture to live comfortably, water sources and humidity provide their prey with ideal living conditions. Anything that reduces spider food reduces spider populations.
  • Inspect the interior regularly – As discussed above, spiders will gravitate toward areas of low traffic. Making a point to regularly disturb all parts of the home will reduce areas of comfort for spiders. In addition, it will help identify developing problems much sooner. In some areas, once or twice a year is adequate, but in higher spider pressure regions, quarterly or every other month may be necessary.
  • Inspect the exterior regularly – most spider populations begin on the exterior of a home. Inspecting or hiring a professional to inspect the exterior of the property will identify populations before they get a chance to expand further on the outside or spread into the structure. Quarterly exterior inspections are usually adequate unless the spider pressure is already high and merits something more frequent.
  • Reduce large populations as encountered – It isn’t necessary to eliminate every spider. As long as they are willing to stay where they are not a bother and are not expanding populations where some may seek your space as theirs receives pressure, they can be great for eating other pests.
  • Adjust lighting – If spiders are hanging around, you can change the type of window coverings to allow less light out of the home, or change the type of lighting inside or out. The types of bulbs from best to worst are:
    1. warm LED
    2. ‘bug lights’
    3. cool color LED
    4. halogen globews
    5. CFL
    6. incandescent