Aphids are small, black or green crawling insects that live in thick colonies along the soft parts of stems, sometimes covering them entirely. They excrete a sweet liquid called honeydew, which often attracts ants. They cause distorted and curled leaves, malformed flowers and hardened buds. Mealybugs are about the same size as aphids but are white and fuzzy. Masses of them, resembling pieces of cotton, nestle and lay eggs where leaves and branches attach to stalks.
Mealybugs can stunt and kill plants by depleting their fluids.
White flies also are small and white, but unlike mealybugs, will take flight if you shake the plant. They come in quantities and can spread to all the plants in your house. Spider mites are miniscule but very destructive. An infested plant will have yellow-speckled leaves and may be covered with tentlike webs. They're easy to spot if you hold a piece of white paper under the plant and shake the leaves so the mites drop onto the paper.