My heart cries with all of yours, i too have VW. i don't wanna go on about stories of discovering them and how to deal with the grub, death to them is plainly obvious....
I LOVE SOLUTIONS!
1.) cardboard rolled for adults as a trap (will try it asap, only question i have is would the trap work if wet -after rain for example or do i than have to roll up a fresh one and during which months did anyone find the best "catch" in cardboard roll?)
2.) microwave! wow! thank you x 1000!!! so far i was burning the soil on my spare drive with some pallets or wood bits but was and am still PARANOID if that was enough, now i have a time limit-6min. Am gonna bag my "bad" soil and start cooking!
3.) nematodes didn't work successfully for me, too many pots and open ground to constantly keep moist, plus every time i discover them the temperature is getting too cold or they just come back.....which brings me on to...I can apply it in my own garden but do i than supply my neighbourhood too??? HA-HA especially since we are all separated by lovely wooden fences that weevils like.....!!!
4.) to be honest i still cannot tell the difference on VW eggs from the pics on the net! Are they? aren't' they? So am doing my own experiment checking daily to confirm what comes out of the eggs i found- snails, earth worms, weevils or slow release fertiliser...??? once i see it with my own eyes i'll learn it for life!
5.) i have pots scattered all around my garden so tray with water even though logical point wouldn't do the trick cos i saw them buggers falling of shrubs and i know they will find a way over the water in saucers- cos they managed "swim the atlantic"!
I much rather like the idea of fresh soil, grit on top- just the watering will have to be softer-softer approach not to wash out the grit.
My question although is- can the adults lay eggs from the bottom of the pot??? For example am always doing loads of cuttings and i keep my pots in cases of 6-8-10 PVC trays from shops and they do have drainage holes, that than lead to pots holes...and some of my plants have juicy root system from the bottom so it only makes sense for them to work their way up... (I am already in my day 5 of putting 2inch of grit on the bottom of ALL MY POTS anyway, but will help me to calm my nerves knowing... )
6.) love the UV torch idea!.. am getting one soon, are adult weevils active Nov- Feb time?
7.) what other traps have you been using for the adults???
(I didn't quiet understood the rigid plastic tubes, could you give me better understanding what you ment by that? thank you)
8.) sand and grit mixed with compost hasn't worked for me... they did find their way to my Sedum after all, laughing in to my face.....
Power of nature is strong, but i hope i will find the strength to battle some more and if any of my experiments work I'll share it with you first thing! Am off to my laboratory and some grubs are going to be seriously tested on!