Parasteatoda tepidariorum

Achaearanea tepidariorum and Achaearanea simulans are near-identical species which cannot be told apart except by DNA analysis. However, the two species have different habitats (see below) Adult Achaearanea tepidariorum are larger (5 to 7 mm) than adult Achaearanea simulans (2 to 5 mm). They are quite distinctive with a teardrop-shaped abdomen much higher than the carapace. Our determinations to species level are based on adult size and the habitat in which the spiders were found, and not on DNA analysis.

Achaearanea tepidariorum is an introduced spider, which, in Britain, is largely confined to warm buildings and especially greenhouses. The similar Achaearanea simulans is found outdoors in a wide range of habitats but rarely if ever indoors. 

All year round.

Uncommon and local in Britain.

Status in Leicestershire and Rutland not known.