Bugs in the wall

On today's home improvement agenda: removal of the wall paneling, in order to put in some insulation (it faces the west, and gets really warm) and also to run some electrical conduit. Looks like there may be some plumbing upgrade happening in there, too, but I digress. I want to document my findings of bugs in the wall. OK, it's not Al Capone's vault, but it's all I've got for now.
   So, here's the wall.


Those dark open areas lead to a little closet outside where our water heater is. It also looks like a really good place for bugs to find their way in. Of course I found ants. Here in SoCal, we are pretty much overrun with Argentine ants, Linepithema humile.  I tried to take pictures of them, but they are tiny and they never stop moving. There were at least two columns of them, marching along the studs on either side of the fireplace.
  There were also numerous daddy long-leg spiders, Pholcus phalangioides. This was no surprise to me, since I often see them in corners, often with little piles of discarded ant husks beneath their cobby webs. But the evidence suggests that these spiders have been making their home in the walls for a very long time.
  Here is the evidence. Lots of exoskeletons. A jumble of skinny legs from who knows when.  There were more piles similar to this on many of the horizontal surfaces within the wall.
  Also entombed was a carpet beetle larva. (Anthrenus sp.)  Was this a spider's prey, or just another exoskeleton in the pile?
  Here's an exoskeleton of a different spider. A black widow, perhaps? I also saw what looked like black widow egg cases.
  And then I saw this. She was trying to hide from my flashlight. I think she was a black widow.  (update:  I removed her later.  There was no hourglass on her underbelly, so she must have been a "false widow", Steatoda sp.)

  My surprise of the day was finding the shell of a mourning cloak chrysalis within the wall!

 
Was it from the caterpillars we had last spring, or some time earlier? What became of the butterfly? Clearly, this piece of evidence asks more questions than it answers.