I’ve looked through the sections on your site, and the closest things I found were the Buffalo Tree Hopper and perhaps the shape of the Red Banded Leaf Hopper. I have quite a few of them (10-20) on my Cycad and once in a while I see them on my lime tree. The like the shade and the underside the best. They can fly but rarely do. I haven’t been able to tell if the shells on the underside are from what they are eating or from nymphs that are hatching. They are pale green in colour with the biggest being about a centimetre long. They have been on the plant for at least a few months. I seem to remember a least a couple being there for almost a year now. I live in Sydney, Australia and the pictures were taken today (it is currently spring time). Thanks for the help!
This is one of the Flatid Planthoppers in the Family Flatidae. We have a similar looking species in the states known as the Chloris, Anormenis chloris.