Rhagium inquisitor in pupal cradle

Rhagium inquisitor in pupal cradle found under bark of rotting log

comments (6)

Ferdy Christant

Lion

Cool! What is this circle-like shape? Posted 8 years ago
1. Pudding4brains
  
  Lion
  
  That is the " pupal cradle" (Dutch: Poppenwieg). Imagine that what you're looking at is after lifting up a loose piece of bark (so the cradle/beetle would be covered directly by the bark top-side. The cradle is created by the larva when it's getting good and ready to pupate. Many beetle larvae living under bark create similar hollow spaces for the pupa to rest in. It provides a bit of protection, but also space for the beetle to emerge from the pupa when ready. The teneral beetle will sit in the cradle until hardened (again - protection for the soft teneral beetle) and usually much longer until "the time is right" (temperature and what have you) to emerge and go find a mate. Posted 8 years ago
2. 1. Ferdy Christant
    
    Lion
    
    Thanks! And how is this circle created? Posted 8 years ago
  2. 1. Pudding4brains
      
      Lion
      
      That is not easily observed ofcourse, but I imagine in this case the beetle larva knaws loose the fibers (you can more or less see that these must have come from the bottom/floor of the cradle - outside the cradle the surface of the tree is higher and quite smooth). Next the larva wiggles it's tail to move the fibers to the side. Something along those lines anyway. Knawing off the fibers is no problem for the larva as it actually feeds on wood(fiber) eating away corridors in the wood and under the bark. Some longhorn beetle larvae are known to tear down wooden buildings this way (not this one) ;o)
      I' ll try and upload some pix of larvae next time I' m home ... Posted 8 years ago, modified 8 years ago
    2. 1. Ferdy Christant
        
        Lion
        
        Thanks! I'm well aware of the hunger for wood of some beetles, a few years back one settled in our garden shed and managed to eat some very long tunnels in some of the softer woods inside. If you would stand next to the shed, you could actually hear it eating, that's how we found out :) Posted 8 years ago
      2. Pudding4brains
        
        Lion
        
        Here is a series of a larva of R. inquisitor I found in a pupal cradle (not the same individual as the image above):
        
        Yes, I once spent the better part of an afternoon determining what wooden boards in a stock of boards for building were making those horrible noises :o) Still have the two larvae I found in those boards somewhere, but never got around to determining the species....
        Posted 8 years ago

The Ribbed Pine Borer

"Rhagium inquisitor" is a species of longhorn beetle in the family Cerambycidae. It was described by Carl Linnaeus in his landmark 1758 10th edition of "Systema Naturae". It is distributed widely in the Holarctic, and its larvae burrow into the wood of larch, pine, spruce, birch and oak trees.

Info 8 0

Similar species: Beetles

Species identified by Pudding4brains