jonathan18:
@Gurezaemon - I came across this larger trap when I was looking at them, though this includes the container as well:
https://www.pestrol.co.nz/buy-online/predator-outdoor-fly-trap-extra-large/ - it's 24x23x36cm
Don't recall coming across any that just had the trap component.
In the end, I decided to go with two of these small ones from Bunnings and also some additional bait (3 pack for just under $10); I'm not sure if having more or a large one like that above would improve the numbers killed, but it could be worth it if it meant fewer of these f__kers...
The packaging says they last three weeks; ours have been out for a month and yet the pile of flies continues to grow. When the liquid level drops I just add more water - at this point I'm wondering if the decaying dead flies are what's attracting the live ones!
Great! Thanks for the input - I'll take a trip to Bunnings over the weekend.