Thrips are a tiny sucking insect that pester Rhododendrons (particularly many older varieties) and Azaleas, some evergreen Viburnums, Photinia, and occasionally other plants in the coastal Pacific Northwest. You can tell you have them because your ordinarily green leaves will develop a silvery sheen on them, while the undersides of the leaves will get little black spots from the thrips’ feces. Click here to see the silvery sheen caused by thrips. While thrips can be a hard pest to get rid of, there are some very effective organic and biological controls you can use. A note about thrip treatment: You should know that the damage from thrips, that silvery sheen, won’t go away even after you kill the pest. All you can do is keep the thrips from damaging any other leaves. So don’t judge the effectiveness of your treatment by whether the thrip damage goes away – rather pay attention to your undamaged leaves and make sure they are staying healthy.