Spider Egg Case

Subject: Unidentified, Unusual Egg Case
Location: Southern Michigan
April 27, 2013 7:39 pm
Dear Bugman:
I found this unusual looking egg case, while hunting for fossils. It was in a crumbly, sedimentary boulder, along with dozens of sow bugs, which were exposed when I split the rock open. The eggs are visible as round bumps through the papery/silky covering. Was wondering if some type of spider made this, or another kind of arthropod such as the sow bugs?
Signature: Chris O

What's That with the Sow Bugs???
What’s That with the Sow Bugs???  A Spider Egg Case.

Dear Chris,
We do not recognize this thing, but we would not rule out a fungus.  We are posting this as unidentified and we hope that either we or our readership might find and answer for you.

Dear Daniel:  After looking all over the internet for similar photos & an answer, I found a link on Bug Guide which has an almost identical photo of this type of egg sac.  It appears to be the creation of a type of ground spider.  Species mentioned during my searching are gnaphosid, zelotes and corrinidae.  Here’s a link to the pic on Bug Guide:  http://bugguide.net/node/view/181688/bgpage

Dear Chris,
Thanks so much for following up on this posting.

4 thoughts on “Spider Egg Case”

  1. Hello,

    I received in the mail a book that I had purchased. Inside was an egg case like this one and a black spider with a white circle around his bottom. It looked as though he had no hair on him and the slightest bit of white on his joints on his legs.

    Reply
  2. Hello,

    I received in the mail a book that I had purchased. Inside was an egg case like this one and a black spider with a white circle around his bottom. It looked as though he had no hair on him and the slightest bit of white on his joints on his legs.

    Reply

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