|University of Kentucky Entomology|
HOUSEPLANT INSECT CONTROL
by Lee Townsend, Extension Entomologist
University of Kentucky Department of Entomology
Several kinds of insects or insect relatives can become pests of home or home greenhouse plants. Usually, it is easier to prevent pest problems than to cure them. Some preventive measures to consider are listed below:
How to Avoid Problems
Buy only healthy plants from certified nursery dealers. The chance of buying infested plants that may appear healthy at the time is greater when buying plants of uncertain origin.
If you discover insect infestations, there are several courses you can take. What you can do will depend on the kind of insect involved, the degree of infestation, the kind of plant involved and its value to you. These are some of the control techniques.
Ants1/16inch to 1/2 inch long black, brown or red insects. They can live in nests or colonies in flower beds, window boxes, flower pots or under greenhouse walks. Ants are attracted to aphids, scales or mealybugs that produce honeydew. Ants will dig up and carry away seeds and seedlings. Repot in a potting media. Be careful to keep ants from transferring in the process. Control of ants, scales or mealybugs on plants also is helpful.
AphidsAphids are sucking insects with soft, rounded bodies. They range from 1/12 inch to 1/8 inch long and their color may vary. They occur in clusters on buds or new foliage. Aphids suck sap, causing reduced growth or stunting of the plant. Feeding by some species may produce distorted leaves. Aphids secrete "honeydew" which gives the leaves a shiny appearance. A black sooty mold may grow on the honeydew. Dip, spray, alcohol swabbing, or washing can reduce infestations.
Fungus gnatsFungus gnats are slender, delicate, mosquito-like flies. The larval stage is a small, active, thread-like white worm with a black head. The larvae live in damp soil and can damage small roots. Plants may drop leaves and generally lose vigor and color. Isolate infested plants. Insecticide sprays will kill adults. Allowing soil to dry more between waterings should help to control the larvae.
MealybugsMealybugs are soft-bodied sucking insects that are covered with white, powdery wax filaments. They occur in leaf axils or branch crotches. Mealybugs suck plant sap and produce honeydew and produce symptoms like those from aphid infestations. Isolate infested plants and treat as for aphids.
MillipedesMillipedes are worm-like hardbodied creatures with 2 pairs of legs on each body segment. They may coil into a circle when disturbed. They hide under boards, flower pots, and other sheltered areas that are damp. Millipedes usually feed on organic matter, but may attack roots, tubers, bulbs, and other fleshy plant parts. Eliminate hiding places and use a bait containing carbaryl (Sevin) or direct spray of insecticidal soap to control.
Cyclamen mitesCyclamen mites are microscopic and almost transparent that infest african violets and cyclamen. They usually occur in protected places on tender growth. Leaves of infested plants are twisted and brittle and may turn black. The buds are deformed and often fail to open. Also, the flowers are deformed and may be streaked. Isolate infested plants and trim off or prune damaged parts. Hot water dipping may provide some control.
ScalesScales are stationary insects with shell-like coverings that protect their body. Some scales may be flat or convex, round, oval, or pear-shaped. Most are brown, but color can range from white to black. Scales produce honeydew, a substance that gives the leaves a shiny, sticky appearance. Sooty mold, a dark growth, may appear on the leaves of infested plants. Plants infested with scales show poor growth or are stunted. Spray or dip the foliage with a soapy wash. Repeat the treatment in 3 weeks and at intervals as needed.
SlugsSlugs are fleshy, slimy animals. They may be light brown to black. Slugs rasp leaves, stems, flowers, or roots. Slugs may produce holes in the leaves or just scar the leaf surface. Silvery slime trails appear where they have crawled over surfaces. Slug baits containing metaldehyde may be used for control.
Sowbugs and PillbugsSowbugs and Pillbugs are oval, hard-shelled, gray creatures that occur in damp places and hide under objects during the day. When disturbed, pillbugs curl up in to a small ball. Sowbugs run for cover. Both feed on decaying organic matter, but may attack rootlets and tender seedlings. Sevin may provide some control. These creatures require humid conditions in order to survive. Allowing the soil to dry more thoroughly should solve the problem.
ThripsThrips are slender insects that are barely visible to the naked eye. Color ranges from yellow, to tan, to brown or black. The younger stages are generally a lighter color than the adults. Thrips rasp leaves and suck sap from leaves and flowers. Injury appears as silvered areas that are speckled with dark fecal spots. The foliage may be blotchy and drop off. Flowers may be streaked, distorted, or fail to open. Infested plants can be dipped or sprayed.
CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication.
Of course, ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY PESTICIDE!
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