Thrips are a winged insect that puncture the leaves sucking nutrients out. They generally will not kill the plant, but do create an undesirable silver marbling look on the leaves.
Early spring will be the first sign of the marbling. Adults over winter in soil and then lay eggs on the plants. The nymphs hatch a few days later and start to suck nutrients from the leaves. In one year, there can be dozens of generations of thrips. Thrip identification and eradication is a year-round process.
If caught early enough, thrips can be managed. The damage that has been done to leaves cannot be reversed, but the new growth can be saved. Soapy water in a spray bottle is the simplest natural method. The soap smothers the insect because it breathes through the skin. Thrips generally live on the underside of a leaf, however it is best to spray both sides. Doing this routinely every week or so, depending on the level of infestation can eliminate the thrip population. Thrips are an annoying pest, but the damage that occurs on the leaves is not a death sentence and can be managed.
Carmody and Sun 