Houseplant Pests
Aphids -
Aphids are tiny sucking insects about 1/8 inch long. they may be winged or non-winged and can be black, red, orange, green, yellow, or tan in color. Ants can play a part in the migration of aphids from one plant to another; therefore, control sometimes depends on the elimination of ants. Damaged plants lose their green color and appear stunted, distorted or curled. This is a result of the insects puncturing individual cells. Aphids secrete honeydew, which gives the plant a shiny appearance and is the basis for the growth of black, sooty mold. Honeydew is a result of plant sugars from punctured cells. I have heard that these insects are born pregnant and lay eggs almost immediately after birth. Controls range from predator insects like green lacewings or lady bugs to insecticides like acephate (Orthene) or resmethrin.
Spider Mites - 
Watch out for these guys, they are persistent and destructive. These guys are not spiders but are related to them. Two-spotted spider mites produce fine webs on the underside of plants. The web protects both the mites and their eggs. Mites are wingless and usually pale yellow or red (sometimes green) in color. Mite damage first appears as whitish or yellowish speckled areas. Leaves may turn bronze and may die and fall off. Warm, dry conditions favor mite infestations. Mites can be hard to control because they reproduce rapidly, building up large populations very quickly. They can develop a resistance to miticides. I personally have seen plants completely cocooned with their webs. With severe infestations it is best to discard the plant. For houseplants I use a powerful spray of: 1 gal. of water, 1.5 tablespoons of dish soap, and 1 tablespoon of tobacco juice. Repeat applications are almost always necessary. Predator mites are a good option for less severe infestations, although finding a dealer can be difficult. Insecticidal soap, insecticides with acephate or resmethrins or also helpful.
Scale - 
Scale comes in many sizes and shapes, but are usually 1/4 inch long. The scale is actually a covering that protects the insect inside. Females lay eggs under the protective covering. When the young hatch, they are transparent, oval and flat. The first growth stage is the crawler. This is the stage when they are most susceptible to insecticide. Look for these pests along leaf veins or leaf axils. Infested plants exhibit poor growth and stunting. Elms, Euonymus and pines are susceptible to scale. Badly infested plants should be discarded. An insecticide containing acephate or resmethrin is also helpful.
Mealy Bug - 
Mealy bugs are slender, flat, soft bodied insects covered by a waxy substance. As they mature, they form a white, cottony mass. Adult mealybugs inhabit cracks and crevices of buds, stems, and branches. They weaken and slow growth of infested plants. Mealy bugs also secrete honeydew. For mild infestations I use rubbing alcohol and Q-tips to control these guys. Just rub them away! For bigger infestations use the soap and tobacco juice mix mentioned under the Aphid section above.
Thrips - 
Female Thrips insert their eggs into the host tissue. One week later the eggs hatch, and within two to four weeks their life cycle is completed. Thrips suck plant juices and in doing so, rasp and shred plant cells. The injured plants turn white and shows signs of black secretions. Thrips are usually found in blossoms and in the axils. of leaves. Spray plant with malathion or Orthene. Remove infested buds and flowers.
White Fly -
Whiteflies are tiny, snow-white insects. Adult females can lay up to 100 crescent-shaped eggs per month on the underside of leaves. Whiteflies will breed continuously in interior environments, thereby creating large populations rapidly. Infested plants become weak, deformed and pale, and eventually die. Whiteflies secrete honeydew. Poinsettias are very susceptible to these pests. Isolate plants due to the mobility of this pest. Spray with insecticidal soap, resmethrin, or Orthene. Sticky, hanging traps sometimes work.
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