Newbie spider enthusiast.

[RobAtkinson]

Hi there guys, i've recently become interested in spiders and was wondering if you could answer a couple of questions for me.
1. Do we have Hobo spiders here in the UK?. If so are they as venomous as their American counterparts?.
2. Is it normal for Pholcus phalangioides to appear in large numbers around the house?.
Thankyou

[faz]

hi cant answer q1

Q2 yes i have lots around my house most in the out side loo

[Mark Burgess]

Hello Rob,

We certainly do have the ‘hobo spider’ (Tegenaria agrestis) in the UK; there is a distribution map here: NBN Gateway: Tegenaria agrestis grid map.

It isn’t unusual to have large numbers of Pholcus phalangioides; we have dozens in our flat, mainly in the bathroom.

Best wishes


Mark

[RobAtkinson]

Thanks guys. There seems to be a good population of Hobo spiders near me. Any idea as to the strength of their venom?. I've heard that there is a difference in strength between Hobo's in Europe and North America.

[Mark Burgess]

Hi Rob,

No difference in venoms between UK and US specimens (see Binford, G.J. (2001) An analysis of geographic and intersexual chemical variation in venoms of the spider Tegenaria agrestis (Agelenidae) Toxicon. Jul; 39(7): 955–68 – abstract below).

I have never heard of T. agrestis biting a human in the UK, but other people here will know more.

Best wishes

Mark


Abstract
The spider Tegenaria agrestis is native to Europe, where it is considered medically innocuous. This species recently colonized the US where it has been accused of bites that result in necrotic lesions and systemic effects in humans. One possible explanation of this pattern is the US spiders have unique venom characteristics. This study compares whole venoms from US and European populations to look for unique US characteristics, and to increase our understanding of venom variability within species. This study compared venoms from T. agrestis males and females from Marysville, Washington (US), Tungstead Quarry, England (UK) and Le Landeron, Switzerland, by means of liquid chromatography; and the US and UK populations by insect bioassays. Chromatographic profiles were different between sexes, but similar within sexes between US and UK populations. Venoms from the Swiss population differed subtly in composition from UK and US venoms. No peaks were unique to the US population. Intersexual differences were primarily in relative abundance of components. Insect assays revealed no differences between US and UK venom potency, but female venoms were more potent than male. These results are difficult to reconcile with claims of necrotic effects that are unique to venoms of US Tegenaria.

[Mark Burgess]

… and from the ever-reliable Wikipedia:

“The one fatality attributed to the spider by medical authorities has also been questioned, and there are no documented cases where an otherwise-healthy person has developed a necrotic lesion from a positively-identified hobo spider bite. Many scientists now question whether or not the spider is harmful at all.”

Mark

[RobAtkinson]

Thanks for that. I already knew that there was debate as to the strength of its venom and the fact that tegenaria species rarely bite. I have to admit though I'm still not too fond of tegenaria species.

[John_M]

From what I've read, it would seem that in the US, the spiders are being blamed for bites when no spider has been seen, and also in areas where the spider is not recorded. I think that in many cases, even if a spider has bitten, the lesions are probably due to secondary infection.
Tegenaria agrestis does not have a reputation for biting, whether medically significant or not, any more than other Tegenaria. The name 'aggressive house spider' was given to it not because it is agressive, but because of a misunderstanding of the species name agrestis.
Tegenaria can be quite fearsome looking, but are not aggressive at all, at least not in my experience.

[No.9 Spider]

Originally Posted by RobAtkinson

Thanks guys. There seems to be a good population of Hobo spiders near me. Any idea as to the strength of their venom?. I've heard that there is a difference in strength between Hobo's in Europe and North America.

You'd have to microscopically examine the Tegenaria species to determine if it was definitely T. agrestis.



No.9 Spider

[nikolai_avenger]

100% of all Tegenaria species I have ever happened upon in the house or garden have chosen flight over fight.

Regards, Nik.