Any spider found within a residential dwelling might rightly be placed in the house spiders category. In fact, most people’s squeamishness around spiders often translates into dramatic interpretations regarding their presence. To this population, it almost goes without saying that any spider found in the house is naturally a giant, gigantic, large and hairy spider, or something close to that description.
True enough. One spider species, Eratigena atrica, a member of the funnel weaving family pictured at the top of the page, also formally goes by the name Giant House Spider because it can grow up to four inches from leg to leg. Its close relative, Eratigena agrestis goes by the name Hobo Spider, with unconfirmed reports of its being a spider of medical importance.
Depending on geographic location, the presence of house spiders can be meddlesome. Some areas such as the Southeast and Northwest tend to attract more spiders into homes because of the presence of larger native spider populations. Houses with overgrown vegetation against the exterior also tend to attract greater numbers of spiders.
All houses occasionally host at least one spider. Consider, for example, the typical spider in the bathtub story. Cobwebs along the the ceilings of residential kitchens and basements indicates the presence of house spiders. Any spider that wanders into a residential area can rightly be considered a house spider. Here’s a quick summary of the different types of house spiders commonly found throughout North America.
Talk of house spiders often begins with Cellar Spiders (Pholcidae), some of the most common spiders found in residences across North America.
Their long legs makes the nick-name daddy long legs appropriate, however, their two body parts puts them in the spider category rather than the Opilione category of another daddy long legs species.The top picture shows a close-up view of the cellar spider’s two body parts.
Cellar spiders build webs similar to another family of spiders called, Theridiidae, more commonly called cobweb spiders. Theridiidae, however, typically do no have the extra long and thin legs like cellar spiders.
The picture in the box on the right shows the spider’s body in relationship to its long legs.
While cellar spiders might be considered an eyesore, they are harmless.
With close to two hundred and fifty species covering over thirty genera, there’s a good chance that a cobweb spider (family Theridiidae) makes its way into the average household. Of course the real problem with cobweb spiders boils down to a few species in one genera, widow spiders in the genus Latrodectus.
Apart from the widow spiders, which fortunately prefer outdoor settings near woodpiles in residential areas, the presence of cobweb spiders in the house presents little cause for concern.
Initial identification of the cobweb spiders is rather straight forward. Most have extra large front legs. Their abdomens tend to be more rounded in shape. The picture shows the triangulate cobweb spider (Steatoda triangulosa) probably the most wide ranging of the species and the most common cobweb spider found in homes and sheds across the United States.
Often the Steatoda species acquire the nickname false widow. The name false widow comes from the spider’s looks. From a distance, the body often appears dark, like the black widow spider. The picture shows a less common species, Steatoda Grossa. With the legs extended, it measures approximately and inch and one-quarter in length.
Their bites are known to cause pain and discomfort for a small portion of the population, however for most people, their bite produces no side effects.
Funnel Web Spiders
Often called grass spiders, the funnel web spiders (Agelenidae) also occasionally wander into houses during cool weather. Looking at their tail end represents one general funnel web identification rule of thumb. Many species have extended spinnerets and this differentiates them from wolf spiders.
A close up picture of the eyes also helps with identification. Funnel web spider eyes are arranged in two narrow and relatively straight rows. The eye arrangement gives them a forward looking appearance.
Most funnel web spiders are not considered dangerous to humans. The Hobo Spider in the Pacific Northwest would be the exception.
Other House Spiders
For homeowners whose houses are build on the ground (probably most homeowners), sometime or another a ground spider (family Gnaphosidae) will wander onto a window sill or wall. Many ground spiders are small and resemble ants like the one in the picture. They present no harm to anyone in the house.
West Coast residents can often find a Mouse Spider (Scotophaeus blackwalli) crawling on a wall. They are a bit larger than the more wide ranging ground spider species, and they are also European imports that found their niche in West Coast homes.
Hacklemesh Weavers, another spider family (Amaurobiidae) also build irregular looking webs in bark and woodpiles. They share many similarities with the Funnel Web spiders, although the funnel web spiders mostly build their webs in grass. Both can live through the winter, and therefore they are often found in households during the cold weather. Physically, they tend to have a two-toned body with a shiny looking cephalothorax and fuzzy abdomen with a pattern. The red cephalothorax of the spider in the top picture is a good field identification clue for the largest members in the Callobius genus.
Sheetweb and dwarf spiders (Linyphiidae) are a very large and often overlooked family of common spiders. In terms of sheer number of species, most experts place the family at, or close to the top of the spider list.
The small size of most species, including the dwarf spiders, means that they they can only be seen with an optical aid. Literally thousands can cover an acre of land at any one time. The larger sheetweb species, such as the Neriene radiata (Filmy Dome Spider) build larger flat or messy dome shaped webs along low growing bushes.
There’s a Spider in My Bathtub
How many times have you heard, said or thought the question, “there’s a spider the size of a tennis ball in my bathtub, what should I do”? There are two answers to the question.
First, you can take comfort in knowing that the question is commonly heard in households with bathtubs around the world. Spiders and bathtubs go together like peanut butter and jelly. The reasoning is simple. During the mating season wandering male spiders travel around the house. They accidentally fall into the bathtub and are unable to escape because of the tub’s slippery sides.
Given the configuration of most modern plumbing systems, it is highly unlikely that the spider crawled up through the drain.
The second suggestion would be to check your math. It is not uncommon for people to exaggerate the size of a spider on first sight. If the spider in the tub is really the size of a tennis ball, there is good news. Your spider is most likely not the more dangerous hobo or recluse spider. It is probably a giant house spider (egenaria duellica) that can measure up to three inches in diameter with its legs extended.
The third course of action is optional, depending on the number and squeamishness levels of the household members. The least squeamish member can trap the spider under a glass, slide a sturdy piece of cardboard beneath the opening, and carry and release the spider in the outdoors.
Please remember to release the spider some distance from your house, or chances are he will soon visit again. House spiders rank among the speediest spiders on earth and yours may very well race you back home.