Raspberry beetle

Hi everyone!

I'm quite new to this forum but think it's fantastic...   

This is my first question, which I'm sure will have been tackled elsewhere already, but a quick trawl in Fruit & Veg hasn't revealed it.

I grow raspberries, both summer & autumn varieties.  The earliest fruits (and most of the autumn ones) are unaffected by raspberry beetle maggots, but just now almost every berry I pick is riddled with the little blighters!  (I still use the reasonable parts of the fruit for jam, but preparation takes for ever.)  Does anyone know of an organic control or parasitic wasp or whatever?  I really don't fancy spraying with something which means I have to wait weeks to harvest any fruit.