Just had a quick google for squirrel deterrents and found this on the RSPB site...
I mixed liberal amounts of chilli powder with bird seed before filling the feeder. Squirrel came down as usual to have a good feed, ever seen a squirrel catapult off a feeder horizontaly? That was last year and they have not been back,at least not to that feeder though the fat balls are demolished with depressing speed. I think the answer is large amounts of chilli powder.
Would a liberal dusting of evil strength chilli powder have a detrimental effect on your bulbs?