By Cbirc
United Kingdom 
My small patio is plagued by bluebottles.They seem to enjoy sitting on the cammelias. We have hosed down to get rid of sooty mould but no help. They also like sitting on white furniture. There are cats but no evidence of dead bodies.We have removed old food from bird feeder. At wits end.
13 Sep, 2015
Answers
As a very long shot have a smell of the flowers on the table - do they smell at all? Some arums attract flies.
Try moving them away and see if it makes any difference.
13 Sep, 2015
There is a plant that attracts flies which is common in gardens - Euonymus varieties, when they are in flower - if you have one of these, the flowers aren't very noticeable to us, but every fly for fifty miles will find them...
Otherwise, if you have sooty mould on your camellia, check the woody parts and the backs of leaves for scale infestation - sooty mould is usually a symptom that follows on from this.
13 Sep, 2015
Do you have neighbors that don't clean up after their dogs?
13 Sep, 2015
Euonymus. We had Silver Queen growing up a house wall and it was a magnet for bluebottles. We couldn't find a solution so, sadly, the shrub had to go. It was lovely but we couldn't stand the swarm of flies each time we walked past.
14 Sep, 2015
The local egg farm were fined for not clearing up the dung, when they did the flies spread across the fields..... yuck ?
14 Sep, 2015
Thankyou now and all for the very helpful comments. I will work through them all and report back if I am victorious!
Cbirc
14 Sep, 2015
There was likely a dead bird or mouse at the base of the bush and the bluebottles laid their eggs in it.
13 Sep, 2015