Wednesday, February 27, 2008

Venomous Spiders Lurking in Your Home


I found this critter on our bathroom wall a few weeks ago.

It's a Yellow Sac Spider, aka Black-footed Spider, of the family Miturgidae. They are very common in US households. Their bites are venomous and cause localized tissue necrosis which basically means an open wound that can take several weeks to months to heal. Yellow Sac Spiders are not aggressive. They typically bite in defense. Their commonality and the tissue necrosis effect is believed to be the cause of many spider bites being blamed on the Brown Recluse. Brown Recluse bites have similiar (and worse) effects, but are much less common.

These spiders don't build a web per se, but a "sac" of silk that they use as a lair. If you've every lifted up an old picture on your wall and found a little web "pouch", it is likely made by this species. I have had encounters with these guys in many places including my car. On several occasions I've been driving along and one crawled across the inside of my windshield out of my defrost vents! Arachnophobia + venomous spider + driving = potential disaster!

13 comments:

corey said...

Yikes!

I certainly wouldn't want one of them crawling across MY windshield...

egretsnest said...

Shudder! I have definitely seen those nightmarish critters in my house and car . . . I could have done without knowing that they are venomous! Ick!

grant mccreary said...

I'm well aware of Black Widows and Brown Recluses, but this is the first I've heard of this one.
I've got no problem with spiders - as long as they aren't in my house or car, or on my person!

Markus Jais said...

Great article. As far as I know here in Germany we don't have venomous spiders in houses but due climate change, more and more venomous species form Southern Europe have been recorded in Germany.

Maybe you should carry a Chickadee with you all the time, that could feed on the spiders :-)

Patrick Belardo said...

Markus, maybe I can teach my parakeets! Too bad they eat mostly seeds and non-animal matter.

That's very interesting about the warming effect on the spiders. I really hope tarantulas don't end up in NJ...

Kennie said...

"twitch twitch" I'm sitting here just freaking out looking at it! Glad I don't really have spiders to worry about up here!

Born Again Bird Watcher said...

A very cool spider indeed and one that we, thankfully, lack out here in Oregon.

Beth said...

YUCK!

lisa said...

Cool...I never knew there was another spider with a necrotizing bite. Good thing they're small!

Anonymous said...

i was bite by something in eastern germany while sleeping in a house. it has been identified as being venomous, but docters are unsure of what it was... any ideas?

Patrick Belardo said...

Sorry I can't be of any help, but I believe there are other species of sac spiders in Europe.

Anonymous said...

I have found the little spider.. two months after i recieved a bite from the critter... or one of his little friends. The bite has not healed after a course of antibiotics... Any ideas? Doctors in South Africa are expensive and if there is anything i can do to avoid doing it i will.. any ideas welcome

mary wille said...

u know i was just told a 4 by 4 inch section of my top foot decaying is due to a brown recluse ,i just went out to get the dog and brushed one of these things of my hand with a loud sceam,not only are brown recluses not suppose to be here,nor r these,there has been 4 people biten this summer from brown recluses up in northern wisco i am in central,global warming???,boy this thing really hurts,mary