Any ideas what this is on my pear tree

I think my poor conference pear tree is ill. Any ideas what this is? Its blossoming like usual but the twigs seem quite brittle.

I agree it looks a bit like scale insects see the RHS site
http://apps.rhs.org.uk/advicesearch/profile.aspx?PID=224

and they do come in different colours, I had grey ones last year on my gooseberries.
I used the Bayer control the RHS recommends, about now, but it would be difficult to apply to a tree of any size.

Looks like Blister Mite. We have it in our pear tree too. Not much you can do about it apparently. The mites hibernate over winter in the buds an then move out into the leaves during spring and summer, going back into the buds later in the year. One recommendation is to wait till later in the summer and removing all th leaves, this taking the mites away before they migrate back into the buds.