It seems to be working. I've harvested 4 more figs, so I am way ahead of the squirrel. I've even left my tree outside overnight as the weather has warmed back up to 19 C in the evening. September is always a wacky month for weather.
Now I am just covering one or two figs at a time with the plastic bag. While this leaves the rest of the figs exposed, they are so small, green and hard, that I doubt they will ripen and I am pretty sure they won't before the end of next week when we leave for Paris. I am hoping that if the rodent with a tail does manage to harvest a green one, it will give him such a belly ache that he'll never try again.
And for those of you thinking of eating or shooting squirrels you may want to read this or this.