Aphid infestations are rarely severe enough to harm your plants, but you want to get rid of them anyway. You'll find aphids, which come in many colors (white, brown, green, red, pink or yellow) feeding on the underside of tomato leaves. Perhaps the easiest way to get rid of them is to wash them off, sometimes with a little soapy water, though many other solutions exist. You can find much more information through our experts here.