Saturday, January 21, 2012

Rhagium inquisitor

The ribbed pine borer Rhagium inquisitor (Linnaeus) is a longhorn beetle that occurs around the world in the Northern Hemisphere. The larvae usually live a couple of years under the bark of dead pines. After pupating in the summer, adults emerge in the fall and overwinter inside a frass wall beneath the bark.

These appropriately named beetles have interested insect physiologists for a number of years because of their ability to withstand harsh sub-zero winters above ground (albeit somehat protected inder an inch of bark). They have a combination of anti-freeze compounds in their blood that enables them to avoid ice crystal formation at temperatures below -16 degrees C. Here are a couple of the frass wall hybernacula that I found last week near Watsonville, California.

We were visiting the beach and I found a couple of the beetles on a dead Monterey pine (Pinus radiata) just a mile or so from the coast. It can be seen in the habitat shot off to the right.


Anonymous said...

Also interesting is their broadly Holarctic distribution - perhaps among the broadest natural distributions of any insect (that hasn't been aided by man).

Sam Wells said...

I agree. It's a bit odd to me to find them in such differing habitats as California coast and New England forest.