Royal Alberta Museum: Invertebrate Zoology - Bug Facts

[Caterpillars and Other Immature Insects]

Fact Sheets: Commonly Observed and Asked About Insects and Spiders Found in Alberta

European House Spider (Tegenaria domestica)

Female European House Spider
Photo CD 0023 3291 1601, Image #45 - Credit: Terry Thormin

Male European House Spider. Note the swollen tips to the pedipalps.
Credit: Terry Thormin

INTRODUCTION

The European House Spider is often called a drain spider because when one falls into a sink or bath tub and cannot climb the smooth sides, people assume it come up through the drain. This spider belongs to the family Agelenidae (the funnel web spiders).

IDENTIFICATION

This is a medium sized brown spider with proportionately long legs. Females are up to 11.5 mm in body length and males are up to 9 mm. The legs are banded with lighter browns and the abdomen is marked with a grey chevron pattern. Adult males can be identified by the swollen club-like tips to the pedipalps (short leg-like structures at the front of the head between the legs and the fangs).

DISTRIBUTION

Throughout Canada and United States. In Alberta it is probably found in all major towns and cities, but is largely restricted to areas of human habitation. This is an introduced species from Europe where it is common in buildings. It is now distributed around the world and from Greenland and the military bases on Ellesmere Island in the Arctic to McMurdo Base in the Antarctic.

TIME OF YEAR

This species can be found indoors all year round. They are more frequently found in the fall when they come inside to escape the colder weather.

HABITAT AND HABITS

Although European House Spiders are found outside under stones and in rock piles, they are most likely to be encountered indoors, especially in barns, garages and in unfinished basements. Females and immature males build webs composed of a flat thick sheet of silk with a circular funnel retreat off to one side. These are often located in a dark corner of a room or similar location created by furniture. Adult males wander around looking for females to mate with, and are thus more commonly encountered.

SIMILAR SPECIES

The Giant House Spider, Tegenaria duellica, looks very similar but is considerably larger. It also lacks the banding on the legs. It is an introduced species from Europe and is gradually becoming more common. It is now found in most urban centres in Alberta. The Hobo Spider, Tegenaria agrestis, is found in western United States and various localities across southern B.C. There are only two confirmed records from Alberta, and those are from St Albert and Grande Cache. The Grande Cache spider is one that was found in a shipment of car parts from British Columbia.

The Hobo Spider is considered to be a dangerous spider because its venom is thought to be capable of causing necrosis (dying of the flesh). Recent research has shown, however, that there is most likely no necrotic component to its venom. Although there is circumstantial evidence of Hobo Spider bites resulting in necrosis, there is only one known case of someone being bitten by this species and developing necrotic lesions, but the patient was suffering from phlebitis, which can also cause such ulcerations. If Hobo Spider bites have resulted in necrotic lesions, bacteria in digestive regurgitant of the spider or on the skin of the person being bitten could be the cause. Unfortunately, wounds that are very similar to necrotic envenomation can be caused by a number of different medical conditions, such as phlebitis. When one of these is responsible, the Hobo Spider is often blamed and the media are still reporting these cases as being Hobo Spider bites. This results in public overreaction. Because more research is needed to completely clear the Hobo Spider, this species should still be treated with caution and respect. The Hobo Spider looks very similar to the Giant House Spider but averages a bit smaller with proportionately shorter legs. Positive identification of the Hobo Spider generally requires examination of the spider under a microscope. Anyone who thinks they have a Hobo Spider, especially if they believe they have been bitten, should make every effort to collect the spider and get it to a local expert.

For more information on the Hobo Spider see the article Potentially Medically Significant Spiders of North America on our web site.

COMMENTS

In Europe where all three species of Tegenaria are found, the Hobo Spider is found primarily in fields and has never been considered to be dangerous to humans. The reason for this may be that other spiders, such as Steatoda spp., outcompete the Hobo Spider and keep it out of houses. It is only in North America where we try to eliminate all spiders from our homes that Hobo Spiders are a problem. We would do ourselves a favour by allowing other spiders adapted to living with humans into our houses. See the Boreal Cobweb Spider Fact Sheet for more information on this.

Note: We cannot provide advice on controlling spider pests. If you need more information beyond what has been provided here, we suggest you either search further on the web, or talk to a local exterminator.

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Last update: November 26 2004