The purp or red will be where the light jits the stems, green on the other side, at least till it gets bad & consumes.
Think sunburn.
Important tip for the sticky traps is knowing when they become less affective.
The cheap two sided ones I get and line the inside of the pot with get sprayed from misting fan leaves and tend to be good for about 3 weeks till I replace them. I have never had this level of control over gnats till I started changing them on time.
Been a while since I made any sprays for gnats.
When I had a problem I'd mist the top soil with capt jacks Spinosad.
Few days later I'd mist the top soil with pyrethrin.
Few days later I'd mist with an essential oil. The one I have now Bee safe 3 in one and uses sesame oil.
Sprays made from concentrate of pyrethrin or spinosad should be made in small batches that are used the same day. Can't make a big bottle and use it for a few weeks, it's best mixed the day it is used.
This trap was put in 2 days ago, I might just beat them this time and I think the sticky traps are playing the key roll in doing it.
@Randomblame - 6 weeks 12/12. Still think she's going to discard these fan leaves?