I was a bit skeptical when I bought this but it's great, I hung it under the eave of our garage near our back door, before using this we couldn't open the door or kitchen window without wasps coming in every couple of minutes. I was using Irn Bru in it (sweet sugary fizzy drink) and it was really working well but one day I swapped to slightly diluted Ribena blackcurrant juice. That worked just as well for the wasps but it also trapped a lot of flies, blue & green bottle types.
One tip if you spill any "bait" on the outside wash it off or the insects will just sit on the outside, each time I hung it up I then washed it down with my sons water pistol, just the trick.