Mysterious hole in the ground

This entry is part 1 of 5 in the series Mysterious hole in the ground

I came upon the hole pictured in the photos while hiking on a fire road in Mendocino county, (California) a few days ago. Hole was about 1.5 inches (4 cm) in diameter, and lined with a filmy white material which is pictured peeled away in the second photo. I probed the hole with a stick, and it was deeper than one foot. Any idea what made this?  Ben

Mysterious hole in the ground

This entry is part 2 of 5 in the series Mysterious hole in the ground

Hi Benjamin, Thanks for writing.  I’m pretty sure that’s a spider hole.  There are at least two large spiders in CA that make holes like that and line them with silk.   One is the Carolina wolf spider (Hogna carolinensis), and the other is the California tarantula (Aphonopelma sp.).  Though I have not tried this, apparently, one method to get a burrowing spider to show itself is to drip water into the burrow.  Probably very annoying to the spider, though.  🙂

In case you are worried, although both of these large spiders can bite, neither is considered to be dangerous to people.  Tom

Mysterious hole in the ground

This entry is part 3 of 5 in the series Mysterious hole in the ground

Hi Tom, thanks for solving the mystery!  That makes sense, as the white lining had a consistency similar to spider web, and now, googling ‘tarantula spider hole’ I see some photos that look similar (though only a few of them show the white lining as prominently).  I like spiders, but have only had the good fortune to come across a tarantula once in my hikes around here…  I’m not sure I would recognize a wolf spider (tarantulas are a bit more distinctive with all the fur!).  If I find another hole like this, I might succumb to the temptation now to empty my water bottle in it!

Thanks again, Ben

Mysterious hole in the ground

This entry is part 4 of 5 in the series Mysterious hole in the ground

Ben, Glad to help.  Thanks for the donation.  Don’t know if you looked up photos of the Carolina wolf spider, but it is also large and at least a little furry.  One of the ways to tell a wolf spider is that they generally have two large up front eyes, with a row of four smaller eyes underneath, so that it looks almost like a smiley (or frowny) face, with two eyes and a mouth.  Click here to see a picture of the Carolina wolf spider.  The California tarantula has much smaller, barely visible, eyes.  So if you pour your water bottle in the hole and something comes up, look deep into its eyes.  Tom

Mysterious hole in the ground

This entry is part 5 of 5 in the series Mysterious hole in the ground

I’ll be sure to have meaningful eye contact with the next large furry spider I see!  And now that I have discovered you and your website, I’ll be sure to contact you with my next nature puzzle… thanks again!  Ben