Tweeters:

I've had many inquiries regarding the aggressive house spider in the last
two days and haven't had a chance to respond. Hopefully you have found
answers on the several web sites listed by Jerry and Sandy Converse. But a
couple of quick points/answers:

The Hobo Spider is the same thing as the Aggressive House Spider.

The Brown Recluse Spider can be told from the Hobo Spider as follows:

The Brown Recluse has a dark brown or black fiddle (or violin) shaped
pattern on the head which contrasts with the lighter color (usually golden)
of the rest of the head. The body is not hairy.

The Hobo Spider lacks the above pattern on the head, and has a light
chevron pattern on the abdomen (less distinct in dark individuals). This
pattern does not occur on the Brown Recluse. The Hobo looks hairy on the
legs and body.

Pictures that will help visualize these species can be found at the Hobo
Spider web site: http://hobospider.org/

Another web site (www.ufsia.ac.be/Arachnology/Pages/Hobo.html) lists a
number of references, one of which is a slightly updated version of the
one I quoted from in my earlier message. You can click on it (the listing
reads: Spiders With general info and Widow spiders, Brown spiders, ......)
and see additional pictures of the Brown Recluse and Aggressive House
Spiders, and some other species in Washington, as well as picture of the
damage Aggressive House Spiders bites do.

But you should also note that there are other species that resemble the
Hobo (some in the same genus) but are not poisonous. Most of these have
legs banded alternately light, dark, light, dark down their length (see
picture in the above reference). The Hobo's legs aren't like that. But, as
noted on both web sites, it is best (especially if you are bit and can get
the critter) to collect the spider and take/send it to an specialist for
ID. They can be sent to:
Plant Diagnostic Clinic
WSU Puyallap
7612 Pioneer Way
Puyallup, WA 98371-4998


How far north do they get? Are they in Alaska? I've heard of no Alaskan
occurrences yet, but I noted that the Hobo Spider web site indicates the
climate in SE Alaska is favorable for them, so the spider may get there.
They are spreading and have been found as far north as Prince Rupert, BC,
and Wainwright, Alberta.


Richard (Dick) E. Johnson
Conner Museum of Natural History
Washington State University
Pullman, WA
johnsonre at wsu.edu