Clark County logo   Clark County Washington title  
Links to finding county services
Search the Web site
Clark County home page A to Z index Find it Links to other sites News releases Contact us

Environmental Services

Recycling, Garbage & Hazardous Waste

Waste Reduction

Garbage Collection & Disposal

Recycling Collection & Disposal

Recycling A-Z Index

Solid Waste Advisory Commission

Household Hazardous Waste (HHW)

Small Quantity Generators (SQG)

Yard Debris/Composting

School Programs

Naturally Beautiful





Recycle A to Z

alternatives to pesticides - bugs/pests - Thrips


Actual size: Up to 1/5”

Thrips are tiny, elongated, fast-moving insects 1/5” long or less.  Adults and nymphs suck sap from plant tissue, leaving silvery spots or streaks on leaves. In the Pacific Northwest, thrips are a particular problem on gladioluses. Thrips can apparently produce young without mating. The process, which is also common in aphids, permits a very rapid population buildup.

Physical control
Sticky Tape - In greenhouses, hanging blue sticky traps helps catch adults before they move into the plant.

Biological control
Predators - Encourage native predators such as lacewings and lady beetles. Because most thrips pupate in the soil, they are potentially susceptible to insect-eating nematodes. Two predatory mites also appear to have substantial potential for thrips control.

Least-Toxic Chemical Control
Alcohol – Alcohol sprays work on aphids, mealybugs, scale insects, thrips and whiteflies. Use only 70% isopropyl alcohol (rubbing alcohol): mix 1 to 2 cups alcohol per quart of water. Using undiluted alcohol as a spray is very risky for plants. Since alcohol can damage plants, you should always test your spray mix on a few leaves or plants first. Tests results should show up within 2 or 3 days.
Diatomaceous earth - Diatomaceous earth made from ground up fossils, it comes in a powder form and is very abrasive. It is a dust that abrades the skin and body joints of insects. Apply just on the undersides of leaves and on soil around affected plants Dry diatomaceous earth also makes an effective slug barrier. Do not inhale the dust.
Horticultural Oil - Horticultural oils are also called summer oils; these are more highly refined than dormant oils, making them appropriate for use on leaves during the growing season.  They can be used to provide temporary relief from thrips while you are waiting for predators to arrive Consult a nursery to locate a suitable product and follow all precautions. Don’t use horticultural oils when plants are flowering.
Insecticidal soaps are highly refined liquid soaps (technically the potassium salt of fatty acids), sometimes combined with citrus oil.  Soaps are normally mixed with water and sprayed onto leaves to control spider mites, aphids, scale insects, whiteflies and other soft-bodied insects. They are contact insecticides, meaning you must wet the pest for them to be effective. They can be used to provide temporary relief from thrips while you are waiting for predators to arrive.  As always, follow package directions and cautions when using these products.
Neem - Neem is a relatively new botanical insecticide derived from a tree. This product is reported to be very effective, with slightly more staying power than some other botanical insecticides. It does, however, break down completely and is less toxic to humans than some botanicals.
Pyrethrum - Pyrethrum is an effective, short-lived, naturally derived insecticide made from chrysanthemum flowers. It is toxic to all insects, including beneficial ones, and moderately toxic to birds and mammals. It should be the last resort for ornamentals and is not recommended on food crops. Avoid using formulations that contain piperonyl butoxide, which is currently being evaluated for its carcinogenicity.  Pyrethrins are the individual chemicals found in pyrethrum. Pyrethroids are a new array of synthetic chemicals, such as cyfluthrin and cypermethrin. They resist breakdown, thus negating their major environmental advantage. With the three names being so similar, they can easily be confused. Pyrethrum is the least hazardous.
Sabadilla - The seeds Sabadilla, a South and Central American plant, are ground into a powerful insecticidal dust. It is effective against grasshoppers, codling moth larva, webworm, aphid, cabbage looper, chinch bug and many household pests. It can irritate mucous membranes and cause sneezing. Honeybees are vulnerable to it. Handle it carefully.



Back to A-Z list