Appearence of VFTs vary with temperature and sunlight. The colour especially, changes under different growing conditions. For instance, a green leaves with red inner trap VFT. It looked as it is when it is grown in Cameron Highland, but the temperature difference (in day and night) in the lowland just couldn't maintain it's inner trap colour. (this is exactly what xMagicsZ had experienced)
This explained why our red vft we bought last time from Sungai Buloh, when the time we obtained it was burgundy red, but it slowly transformed to greenish maroon no matter how much sun is given. It never return to it's original colour since then.
I have a few VFTs which have red inner trap, every single trap it grows beared the red colour in the trap, others just don't show the red colouration under same condition.
I think it is very much depends on what VFT form we have, some get red easily but others don't.
How many hours did you place your VFT under direct sun? To get the best colour, you may probably need 8 hours.
If you are using water tray system, just allow a maximum of 1 cm of water in the tray and let the water to dry out before you water again. I think mosquito larvas will have no chances of surviving. When you add water, do it slowly from the top but don't splash on the trap so that you won't trigger the trap to drain it's energy unnecessarily. Pour away the water in the tray every week or two to get rid of any minerals accumulated in the tray. Hope this help and explained what you're asking. Happy growing!
