Posted: 12/07/2015 at 21:54
Autumn fruiting rasperries like Autumn Bliss should be cut back to the ground in February. If you don't cut the canes down the old canes will produce a crop at this time of the year but the normal late summer crop will be much reduced or will be absent. The maggots will be those of the raspberry beetle which lays its eggs in about May and when they are fully fed they drop into the soil and pupate ready to start the cycle again.
To get rid of the beetles you need to break this cycle. Although it means losing this years crop (which, if they are maggoty I shouldn't think you will miss too much!) I would cut off all fruit and flowers now and throw them in the dustbin. This will also get the plants back on their normal cropping cycle as long as you remember to cut all of the canes back to the ground next February.