Some thrip species are beneficial insects, but others do serious damage to flowers, fruits and vegetables. Different types may attack specific plant families, but these pests strike garden favorites from roses and raspberries to tomatoes and onions. Adult thrips feed on plants and lay eggs on or inside plant leaves. The eggs hatch into hungry larvae that can mature in as little as two weeks. Multiple generations occur in a single growing season. Thrips also can transmit serious plant diseases.
Identification: Common thrips are tiny, rice-shaped insects best viewed with a magnifying glass. Their slender bodies are often just 1/32 to 1/20 inch long. Adults vary in color from pale, translucent amber to brown or black. They have two pairs of wings fringed with distinctive, featherlike hairs. Wingless nymphs are smaller and lighter in color.
Signs/Damage: Thrips damage plants by rasping and slicing plant tissue and feeding on oozing sap. They typically feed on the undersides of leaves, following along leaf veins. Damage appears on the upper sides of leaves as silvery white specks or small lines. Plants become stunted. Leaves crinkle and drop. Fruit becomes deformed, scarred or scabby.
Control: Because of their small size, thrips often go unnoticed until damage is done. Effective treatment starts early in the season, before populations grow. GardenTech® brand offers highly effective options to kill thrips by contact and keep working for up to three months. These products can be used to treat onions right up to one week before harvest, and tomatoes or raspberries up to one day before you pick and eat*:
- Sevin® Insect Killer Ready to Use simplifies treating individual plants and small garden areas. The adjustable nozzle lets you select a direct stream or a broader spray. Cover all plant surfaces thoroughly, including buds, fruit and the undersides of leaves.
- Sevin® Insect Killer Concentrate provides an economical and efficient option to treat larger vegetable gardens and ornamental plantings. Use with a pump-style sprayer, and cover all plant surfaces thoroughly. Give special attention to the undersides of leaves.
- Sevin® Insect Killer Ready to Spray measures and mixes automatically as you spray. Attach the container to a regular garden hose, and spray to cover all plant surfaces thoroughly, including the undersides of leaves.
Tip: Thrip damage and reproduction peak during hot, dry conditions. Keep gardens irrigated well to reduce susceptibility to thrip damage.
* Always read product labels and follow the instructions carefully, including guidelines for pre-harvest intervals on edible crops.
GardenTech is a registered trademark of Gulfstream Home and Garden, Inc.
Sevin is a registered trademark of Tessenderlo Kerley, Inc.
- "Thysanoptera" by Mick Talbot licensed under CC BY 2.0
- "Tubuliferan thrips (several stages in life cycle), and feeding injury to leaf" by Scot Nelson licensed under CC BY 2.0
- "Pole beans: Thrips feeding injury" by Scot Nelson licensed under CC BY 2.0
- "Onion thrips (Thrips tabaci) Lindeman, 1889" by Alton N. Sparks, Jr. at University of Georgia (Bugwood.org) licensed under CC BY 3.0 US