House-spider - Eratigena

Alternative names
Tegenaria gigantea agg., Eratigena duellica agg.
Description

Females can reach 18 mm in length, with males having a slightly smaller body at around 12 mm to 15 mm in length. The female leg span is typically around 45 mm. The leg span of the male is highly variable, with spans between 25 mm to 75 mm being common. The former genus Tegenaria has recently been split: Tegenaria spp. have banded legs, Eratigena spp. have plain legs. Beyond this distinction, species can only be identified (with difficulty) by examination of the genitals of mature specimens. The term "Eratigena atrica group" has been commonly adopted for the species E. atrica (rare), E. duellica, E. saeva, and their hybrids. Because of the difficulty of separating these species, they can confidently be identified to genus level but not beyond unless there is confirmattory evidence from microscopic examination. 

Similar Species

These spiders were previously in the genus Tegenaria (with banded legs) but this was changed to Eratigena (with plain legs) a few years ago. Eratigena atrica may represent a complex of three closely-related species but but opinion is split, so these species are frequently referred to as the "Eratigena atrica group" because they are so difficult to separate. Eratigena duellica, E. saeva and E. atrica are all of a similar size and cannot be reliably separated without examining the genitalia. E. atrica is rare and has not been confirmed in VC55. E. saeva has a distribution covering Wales, Western and Northern Britain and has also not been confirmed in VC55. 

Identification difficulty
Recording advice

Examination of the genitalia is required to confirm this species.

Habitat

Indoors in dark corners, between boxes etc. where there is little disturbance.

When to see it

Males can often be seen wandering around during the late summer and early autumn looking for a mate. Females can reputedly live for several years and can survive for months without food or water.

Life History

They make large and substantial sheet webs with a funnel to their safety retreat.

UK Status

Common and widespread in Britain but fewer records come from the north.

VC55 Status

Common in Leicestershire and Rutland.

Further Information

2390 British records to Jan 2013

be our species champion

Leicestershire & Rutland Map

MAP KEY:

Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map