Insects on Houseplants (5709)

The insects and mites that infest houseplants are hard to control. To control these problems you must identify problems correctly and early. Timing is important, as is proper selection of control options. Most insect problems arrive with new plants or with plants you have outside for the summer. Isolate these plants for six to eight weeks before you mix them with your other indoor plants.
     
Spider mites attack all houseplants and often break out during the early winter when humidity is low.  Plants look silvery or bronze and leaves eventually turn brown and dry up. Shaking plants over white paper reveals yellow or reddish walking dust-like spots. These are the mites.  Spider mites are resistant to most insecticides, so you'll need to use a miticide or insecticidal soap for control.

Apply sprays twice, spaced ten days apart. Concentrate on the undersides of leaves, and cover the plant thoroughly.

Mealy bugs are white, fuzzy, cotton-like insects that suck juices from the plant. Scale insects are often hard to identify because they're covered with a brown, red, or blackish waxy shield. The first sign of scale or mealy bug problems is often the shiny, syrupy film called honeydew. The insects deposit the honeydew on leaves and stems. Because both scale and mealy bugs have life stages that are resistant to treatment, spray at least two, preferably three, times spaced ten to fourteen days apart.  Insecticidal soaps work well to control mealy bug and scale insects.

Thrips are tiny 1/6 to 1/10#, slender, yellow, or brownish insects that feed on leaves and flowers. They often hide in buds and young tissue. Their feeding causes brownish scratches or distorted, curled plant growth. Thrips are hard to control because they live and feed in well-protected sites. You need to make three to four aerosol or foliar spray treatments spaced five days apart for control.

Whiteflies are small, weak insects that are often associated with poinsettia and fuschia plants. Whiteflies cluster on the undersides of the leaves and can build to high numbers. Because they are hard to control, you should consider disposing of infested plants. Alternatively, spray the plants every five days for a total of three to four treatments with an indoor houseplant spray such as resmethrin or insecticidal soap.
     
Aphids are small, green, red, or brownish insects that cluster on the succulent shoots and buds of various foliage plants. Plants may wilt or yellow due to the feeding stress aphids cause. Apply sprays with soaps or houseplant insecticides twice, spaced eight to ten days apart.

For more information on this subject, Please visit the College of Agricultural Sciences Publications Web site.

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