Tag Archives: False Widow

Autumn is for Arachnids!

Last month I held my 2nd annual virtual event, “September Spider Sleuthing in the San Juans.” Little did I know it would turn out to be so popular. Even the Journal of the San Juan Islands interviewed me. One of the questions asked was, “What led me to create the event in the first place?” Let me answer that for you.

Well, I happen to be an entomologist (someone who studies insects), but after living here for twelve years, I’ve come to LOVE the diversity of spiders that share our islands. I want to help others understand how important spiders are in our ecosystem and dispel some of the unfortunate and undeserved myths associated with our eight-legged friends.

This week, the spider sleuthing continues, albeit informally. I received some emails about spiders, and actually had two folks drop off spiders at my husband’s office in little cups for me to take a look at. “What ARE these?” inquiring minds wanted to know.

One was a suspected Black Widow that turned out to be a look-a-like False Widow (Steatoda grossa). While instinctively protective of the little sack of clustered eggs laid in a matrix of messy web in the plastic cup, I could sense she was alarmed. I was able to remove the lid and take a few photos without disturbing her too much. For now, she remains in the plastic cup. I may relocate her and her egg sack to our greenhouse tomorrow. Steatoda grossa spiders are not medically significant to humans. She’s a friend. Her presence helps keep the actual black widow spiders from colonizing our homes.

Steatoda grossa spider with egg sack
Steatoda grossa spider with egg sack
Steatoda grossa spider with egg sack
Steatoda grossa ventral view

The other cup held two spiders. All I knew ahead of picking them up was they were presumed deceased. One of those two spiders moved ever so slightly when I opened the lid. Where there is movement, there is LIFE! I was mesmerized with this spider, a Woodlouse hunter (Dysdera crocata). After photographing this beauty, I set it free in our stack of cut wood that doubles as a fence along the edge of our property. It will find plenty of isopods in the forest floor and the wood will double as a nice winter home with all its nooks and crevices. Woodlouse hunters are also harmless to humans. Consider them friendly!

Woodlouse Hunter (Dysdera crocata)

The last poor little soul was unfortunately frozen after it was collected. Yes, I opened the lid knowing this, but imagining movement, and hoping that maybe it hadn’t been frozen long enough to kill it. I don’t personally enjoy killing bugs. They’re much more interesting to me alive. I took the post mortem photos, but I’d have preferred being able to resurrect it.

Callobius severus

This sweet little dude is a Hackelmesh Weaver. His scientific name is Callobius severus. He’s harmless (a friend). He was only trying to find a mate. Male spiders often wander this time of year in search of a female. Look at those little palps! Those are the organs the male spider uses to transfer sperm to the female. They looks like little paws…or maybe tiny furry boxing gloves. I’m sorry this fella didn’t find a friend. May he R.I.P.

Callobius severus
Callobius severus

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Steotoda grossa (The False Widow)

It’s been raining a lot in the Pacific Northwest. Between the deluge and the cool temps, it’s definitely not the season for bug viewing. Being indoors, in rainy winter weather, when you live on an island equals boredom, cabin fever, and winter blues. You have to make your own sunshine or you get SADD.

I found my sunshine today in the barn. I went down to take better photos of the spiders I discovered over the weekend residing in the well pump house (inside the barn). I get really excited finding any sort of invertebrate this time of year.

This shiny arachnid had me fooled the first time I found one. She’s not a real widow, but a False Widow (Steotoda grossa). False widow spiders are not native to Washington. They were imported from Europe, but are widely distributed and considered a cosmopolitan species. We have lots in the basement of our house!

When I was in the well pump house, I found three females, each in her own corner, tending her egg sacks.

A very shiny Steotoda grossa female

I also found a lone Callobius severus (male?) on the wall… just hanging out. He was alive. I gently blew on him to see if he moved. He did.

Callobius severus (male?)

Steotoda grossa spiders are actually quite beneficial, preying on invertebrates like pillbugs, but they are famous for eating other spiders that humans don’t particularly want to encounter, like Hobo spiders or Black Widows. They construct flimsy or loosely woven, somewhat messy webs and seem to love corners in outbuildings and basements (at least from my personal experience). Female Steotoda grossa spiders have been recorded living as long as 6 years, while males have a much shorter lifespan no longer than 1.5 years.

Loosely constructed Steotoda grossa web with round egg sacks

While not aggressive, Steotoda grossa spiders will sometimes bite people. They see very poorly and react mostly to vibrations when responding to threats. A bite from a False Widow is not life threatening, but some individuals may have a localized reaction to the bite.

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Steotoda grossa female with egg sack

Steotoda grossa female (upper center, above red mark) with egg sacks