Posted: 12/05/2013 at 15:26
Like all insects, sawflies probably have good and not-so-good years. This might be a good period for them (but bad for you). I think you will either have to live with it or start zapping everything in sight, which seems a little unfair on the already depleted insect world.
There are many different sawflies that are hosted by different plants or groups of plants. Willows wouldn't have survived all these thousands of years if the attacks were fatal.