I have quite a few house plants. A couple of them have been looking funny lately. A couple of my plants (Lilies and lipstick) have started to have wrinkled leaves which were once healthy smooth and shiny. I once had a jade that started to wrinkle up like this. I think it may have been caused by fruit flies. Has anyone seen this before? What is the cause? How can I nurse them back to health?

Also, what is the difference between leaves that are yellow at the tip and those that are turning fully yellow. I was told once that yellow tips mean that you are over watering. Do full yellow leaves mean under watering? What about yellow tips? My corn plant is having the problem of fully yellow leaves. So are my lilies.