Bark Beetle Galleries

Bark beetle galleries. Hayes Common, 25 December 2011.

Another Christmas day find was a fallen tree with much of the bark missing. In the wood below were these intriguing patterns.

These, known as galleries, were created by bark beetles while the tree was alive. The deep central groove was made by the parent beetle, which crawled along laying eggs on both sides. When the eggs hatched, the larvae ate away at the nutritious cambium, the part of the wood just below the bark. They radiated out from the central groove until they were large enough to pupate and then emerge as adults through holes in the bark.

The patterns made by bark beetles are said to be typical of each species, and these were probably the Elm Bark Beetle.  It was actually quite thrilling to find the remains of a large, mature elm that must have been lying there since around 1970.  The results are quite pretty, but there were so many on this tree that I can't help thinking that these might have killed the tree even without the fungus disease that they carried that wiped out nearly all the British elms. You can also see occasional holes where other beetles have bored more deeply.

Bark beetle galleries.  Hayes Common, 25 December 2011.