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News Clippings
9/13/98
Hobos known for bad attitudes
Gary Larson drew a cartoon some time ago that depicted
a frantic spider telling his buddies about the attack:
"Here I was, snug in this shoe, minding my own
business, when suddenly I was attacked by a giant
five-headed monster!" A large foot lay nearby, toes
up.
Hobo spiders move into houses about this time every year.
And none of them ever earned a "plays well with
others" comment on their report cards.
Hobos are large, brown spiders that are cannibalistic,
lousy climbers, frequently get tangled in other spiders'
webs, are big eaters and live life mostly alone. No
wonder they have bad attitudes. Nobody likes to see them
sprinting along a baseboard at 15 to 20 inches per
second.
Hobo spiders, Tegenaria agrestis, are big brown spiders a
good 1 1/2 inches across with thick, hairy legs. And they
bite. They used to be called "aggressive house
spiders" because they'll bite with little
provocation.
Mature females usually sit in their tunnel webs and wait
for prey. When an insect is trapped, she runs forward,
forelegs upraised, bites her meal to subdue it, and runs
back with it into the tunnel. Often, males looking for a
date find themselves her next meal if they fail to signal
the secret handshake, or if she's just plain in a bad
mood. Both will readily eat their young, and the young
will eat each other, given the opportunity. Not an Ozzie
and Harriet-type family.
For years, brown recluse spiders have been blamed for
bites on humans and pets, but brown recluse spiders don't
live here.
They are only found from the Midwest to Deep South,
unless one accidentally gets transported. The only brown
recluse found in the Northwest was in Prosser, Wash., in
1978 when a moving van brought it in.
Never again have we seen another brown recluse. Hobos
arrived in Seattle in the 1930s and quickly spread across
the Northwest.
Venom from Hobo spiders produces skin injuries similar to
those caused by the brown recluse, hence the confusion.
The initial bite is not painful, but in about 30 minutes,
a small, insensitive, hard area appears. That will be
surrounded by an expanding reddened area of 2 to 6 inches
around. Within 15 to 35 hours, the area blisters. About
24 hours later, the blisters break. A cratered ulcer
crusts over to form a scab. Tissues beneath the scab may
die and slough away. Sometimes surgical repair is called
for, according to WSU Extension Bulletin 1466.
If you are bitten, see a doctor right away. T. agrestis
have not caused a death hereabouts, and in Europe, their
homeland, there are few records of bites from these
spiders causing medical problems. That might be because
Europeans have learned to take precautions. Always wear
gloves when working in dense, low brush or places you
cannot see into clearly. That goes for moving firewood,
too. Tegenaria prefer cool, moist areas such as basement
window wells and crawl spaces. Inspect your door and
window casings for gaps. Fill all holes, including those
surrounding water pipes and electrical lines, with
expanding foam. Before you bring in firewood, look it
over for spiders or egg sacs.
[It is strange that the same spider that lives in the
UK rarely if ever is blamed for bites (I have never come
across any medical information about these in the UK), is
the change of attitude due to temperature, or some other
environmental issue?. I have a garden full of Tegenaria
and have never been bitten, at least some of them are T.
agrestis and I do handle all the UK native spiders]
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