Hi Birdman,
There is a good site here in Australia, if you follow this link
http://www.treesrus.com.au/hints_pests.html it has a section on boreres and how to kill 'em.
Basically they say
"
Borers - Borers often attack old, weakened or damaged shrubs and trees, entering the effected area. They tunnel into the plant leaving a mass of sawdust.
Control: Best defense is to keep plants well fed and watered. Scrape away damaged bark and attempt to bring out the borers. More effective is to squirt a few drops of methylated spirits or kerosene into the borer tunnels and putty up the holes to prevent water entering."
Make a link to that page though, it may be useful for other pests later
Cheers, Pete Wilson-Jones