It's important to identify thrips and the damage they cause in order to properly treat the problem. Many species feed within the plant buds or curled leaves, so they can be very difficult to detect. The first sign of thrips is usually yellow or bleached spots on leaves, deformed leaves, or dead blotches on flower petals. Next, the leaves are likely to take on a silvery varnish-like look and black spots from the thrips' excrement. Eventually, the leaves and petals will become deformed, or become thin and wilted, then die and drop off. These symptoms are similar to many fungal or viral diseases, and in fact, thrips are often implicated in the spread of plant viruses and other plant diseases. But if the plant damage is due to thrips, the leaves will nearly always show the black spots created by the pest's excrement.