Suppress ActionController::RoutingError in logs

My rails log get chock a block with things like
<<<<<<<<<<<<
ActionController::RoutingError (No route matches "/admin/Y-
ivrrecording.php" with {:method=>:get}):
...
ActionController::RoutingError (No route matches "/manager/html" with
{:method=>:get}):
..
ActionController::RoutingError (No route matches "/webdav/test" with
{:method=>:get}):
...
ActionController::RoutingError (No route matches "/
javascripts/).html(" with {:method=>:get}):
<<<<<<<<<<<
These are just spurious attempts to access the server and nothing to
do with my rails app.

They are taking up more log space and processor time than I would
like.

Any advice on how to either suppress them from the logs or even better
head them off before they hit rails would be appreciated.

I have seen some apache config in various places to attempt stuff like
this but it is pretty scary when you are not sure if it is right...

Cheers
George