Controls For Leafhoppers
The key aspect of managing leafhopper infestations is to detect them before it becomes too difficult to deal with. Plant inspection is one detection method. Another method is to use Yellow Sticky Traps, placed slightly above crop height.
Pyrethrins, which are derived from the flower of Chrysanthemums are effective against leafhopers as well as many other garden pests . Pyrethrins are eco-friendly, however they need to be frequently re-applied as they degrade approximately 24 hours after being applied.
Not all predatory insects will attack all varieties of leafhoppers, as they are not truly a single species, but rather a "Category" The Praying Mantis and Lady Bugs probably attack the widest array.
Ladybug Lures Keeps trapped ladybugs alive in the trap for release in the garden. Pheromone based Lures will attract lady bugs from the surrounding area to your garden.
Methods of Suppression
Control weeds to avoid breeding grounds, and wintering space.
Follow Crop rotation guidelines
For indoor plants and seedlings avoid putting susceptible plants close to windows, vents or doors, Bugs don't knock before they enter, if they did you probably wouldn't hear it anyway.
Destroy and discard infected plant material
Garden Web - Leaf Hoppers
American Horticultural Society Pests and Diseases: The Complete Guide to Preventing, Identifying and Treating Plant Problems
Insect Guide - Leaf Hoppers