Giant house spider

Eratigena atrica

The giant house spider is one of the biggest spiders of Central and Northern Europe. Previously belonging to the genus ''Tegenaria'' , it is now a member of the newly described genus ''Eratigena'' and is a close relative of both the domestic house spider and the infamous hobo spider. The bite of this species does not pose a threat to humans or pets, and it is generally reluctant to bite, preferring to escape.
Scary Surprise Every now and then these giant house spiders (up to palm width including legs) are found on the floor while walking through my house. I've encountered more here than in the wild but I always send them on their way into the garden. Eratigena atrica,Geotagged,Giant house spider,Spring,United Kingdom,arachnid,bug,macro,spider

Appearance

The two sexes do not differ in coloration or markings. Its coloration is mainly dark brown. On its sternum is a lighter marking, with three light spots on each side. The opisthosoma features a lighter middle line with six "spots" on each side. The Giant house spider has the same coloration as the Domestic house spider; it has earthy tones of brown and muddy red or yellow. They also have conspicuously hairy legs, palps and abdomen. In contrast to other related species, ''E. atrica'' and the smaller ''E. picta'' have uniformly colored legs. In other species, the legs are annulated or spotted. Female body size can reach 18.5 millimetres in length , with males having a slightly smaller body at around 12 to 15 millimetres in length. The female leg span is typically around 45 millimetres . The leg span of the male is highly variable, with spans between 25 to 75 millimetres being common.

Its eight eyes are of equal size and are arranged in two rows. As the eyes contain fewer than 400 visual cells, ''T. atrica'' can probably only distinguish light and dark.
Giant house spider close up  Eratigena atrica,Geotagged,Giant house spider,Summer,United Kingdom,arachnids,isle of wight,spiders

Distribution

''T. atrica'' is found in Europe up to Central Asia and Northern Africa.

In the last few years the spider has been found in several European countries, like Estonia, Latvia and Lithuania. It is recorded in the checklist of Danish spider species.

It was introduced to North America, where it is now established.
Monster spider I never imagined I would find a spider as big as the rain spiders of South Africa, but here it is! At least 6cm across including legs. Thrilled! Eratigena atrica,Geotagged,Giant house spider,Summer,United Kingdom,arachnids,isle of wight,spider

Behavior

''T. atrica'' often builds its funnel web in undisturbed corners. The web does not contain glue, and if an animal gets entangled in the web, the spider runs towards it, crushes the animal to a pulp, which is then digested.

''T. atrica'' normally lives for two or three years, but lifetimes of up to six years have been observed. While the female only leaves its nest to feed, males can often be seen wandering around houses during the late summer and early autumn looking for a mate. Males can be found from July to October, adult females occur all year.

At least 60 spiderlings emerge from an egg sac. Unusual for spiders, they are subsocial at this stage: they remain together for about a month, but do not cooperate in prey capture. The amount of cannibalism correlates with the amount of available food. ''T. atrica'' molts seven or eight times before reaching the immature adult state, and after a final molt reaches maturity.

Like most spiders, the spider possesses venom to subdue its prey. Since ''E. atrica'' bites can penetrate human skin on occasion, the effects of agatoxin might be felt by bite victims, though these spiders will not bite unless provoked.

With speeds clocked at 1.73 ft/s , the giant house spider held the Guinness Book of World Records for top spider speed until 1987 when it was displaced by sun spiders although the latter are not true spiders as they belong to a different order.
Injured! This spider has suffered an injury since it has lost one of its eight legs. Wonder what the other guy looks like? The photo was taken on the concrete just outside the back door. Giant House Spider? The Douglas Fir needle is 22mm long. The fir needle was easier to measure than the spider. Canada,Eratigena atrica,Fall,Geotagged,Giant house spider

Habitat

The giant house spider is indigenous to north western Europe. However, it was unwittingly introduced to the Pacific Northwest of North America circa 1900 due to human activity and strongly increased in numbers for the last century. Its original habitat consists mostly of caves, or dry forests where it is found under rocks, but is a common spider in people's homes.

The webs built by the giant house spider are flat and messy with a funnel at one end. The spider lurks in the funnel until a small invertebrate happens to get trapped in the web, at which point the spider runs out and attacks it. They usually build their webs in corners , between boxes in basements, behind cupboards, in attics, or any other area that is rarely disturbed by large animals, or humans. Often found near window openings.
My Eyes Are On You! All eight of them. The “stump” of the severed leg is easily seen. Canada,Eratigena atrica,Fall,Geotagged,Giant house spider

Cultural

Humorist David Sedaris has written about his relationship with ''E. atrica''. His essay "April & Paris" documents his growing affection towards and domestic association with giant house spiders, particularly one named April. The essay can be found in the collection ''When You Are Engulfed in Flames''.

References:

Some text fragments are auto parsed from Wikipedia.

Taxonomy
KingdomAnimalia
DivisionArthropoda
ClassArachnida
OrderAraneae
FamilyAgelenidae
GenusEratigena
SpeciesE. atrica