In article ,
William Brown wrote:

I get one or two of these growths on my blueberry bushes each year. At
first I thought it was some sort of cocoon, but I cut one open and
didn't see what appeared to be an insect. They usually grow at a joint
between branches and, if left alone, eventually become brown and woody.
I have some pictures of a new one I just picked off at
http://mywebpage.netscape.com/wbrown...nt/photos.html

Looks like a gall of some sort. It may have been caused by a virus,
fungus, or bacterium, but more likely was the home for a brood of little
wasps which have long since left their nursery.