Hoppers are generally 1/4 to 1/3 inch long, and are green, brown or yellow, often with colorful wing markings. They are easily distinguished by their wedge-shaped wings held in a roof like position over their bodies.
In both their nymph and adult stages, hoppers suck juices from plant leaves, buds and stems, and remove chlorophyll from plant cells. They thus weaken plants, and furthermore may spread viral diseases. Leaves may display such symptoms of hopper damage as white or yellow mottling, distortion, discoloration, shriveling and/or dropping. Check also for honeydew excreted in large amounts, which may encourage growth of sooty black mold. The list of vulnerable flowers and vegetables is fairly extensive, and includes, respectively: annual aster, baby's breath, coreopsis, cosmos, dahlia, marigold, nasturtium, petunia, poppy, rose, salvia and zinnia; beans (lima and snap), beets, carrots, celery, chard, citrus, eggplants, lettuce, potatoes, raspberries, rhubarb, spinach, squash (summer and winter), tomatoes, and most fruit trees.
To control serious infestations, use insecticidal soap . Alternately, spray pyrethrins on all surfaces, particularly the undersides of leaves, at 3 to 4 day intervals. Prevent future infestations by keeping your winter garden clean and/or by using cover crops. In addition, attract chickadees, purple finches, sparrow, swallows, titmice and wrens to your yard with the appropriate food and shelter; all eat hoppers.
Specific recommendations for vegetables. One variety of hopper, known as the beet leafhopper, is 1/8 of an inch long, pale green or yellow, and resembles a tiny white fly when flying. It carries a tomato virus for which there are no controls once plants become infected. Symptoms of this virus include a pronounced upward rolling of fully developed leaves, leaves turning yellowish with purple veins, foliage becoming stiff and brittle, and eventual mortality. Another variety of hopper, the potato leafhopper, can reduce potato yields significantly by secreting substances which decrease plants' photosynthesis.
In addition to the controls mentioned above, try excluding hoppers from vulnerable early spring crops with an agricultural fleece barrier. Alternately, apply a preventive spray of insecticidal soap and seaweed extract to vulnerable crops during first month of growth.