Thrips
Pest · Commonly affects: Onions, Tomatoes, Peppers, Beans, Roses, Cucumbers
Thrips are tiny, slender insects that feed on leaves, flowers, and fruit by rasping the plant surface and sucking out the released sap. They matter to gardeners because heavy feeding scars produce and distorts new growth, and several species also spread plant viruses that no amount of care can cure once introduced.
How to identify it
Adult thrips are very small, usually less than a sixteenth of an inch long, with narrow bodies and fringed wings, and they range from pale yellow to brown or black. Because they are so small, you often notice the damage first: silvery or whitish stippling and streaks on leaves and petals, along with tiny dark specks of excrement. Tapping a suspect flower or leaf over a sheet of white paper will dislodge the fast-moving insects and make them easier to see.
Damage
Feeding removes the contents of surface cells, leaving a silvery, stippled, or bleached appearance on leaves and flowers, and it can deform buds so blossoms open crooked or fail to open at all. On fruit and vegetables this rasping causes scarring, russeting, and discolored patches, and some thrips transmit tospoviruses such as tomato spotted wilt that stunt or kill infected plants.
Prevention
Give plants proper spacing and steady, balanced watering so they grow vigorously and shrug off light feeding, and avoid pushing lush, tender growth that thrips prefer. Clean up weeds, spent flowers, and crop debris that shelter overwintering thrips, and rotate susceptible vegetables to different beds each season. Where available, choose virus-resistant or tolerant varieties, and inspect nursery transplants closely before setting them out so you do not import an infestation.
How to manage it
Prune out and dispose of badly infested buds, flowers, and shoots rather than composting them nearby, and a firm spray of water can knock many thrips off leaves and disrupt their feeding. Encourage or introduce natural enemies such as minute pirate bugs, predatory mites, lacewing larvae, and ladybugs, which feed heavily on thrips, and keep flowering insectary plants nearby to support them. Sticky cards, especially blue or yellow, help you monitor populations and can trap adults, while lightweight floating row covers exclude thrips from young plants when they are not relying on insect pollination.
General guidance for US home gardens, focused on prevention and non-chemical control. For a confirmed diagnosis and options specific to your area, contact your local Cooperative Extension office. Page updated Aug 4, 2026.