Scouting Tips for Onion Thrips in Onions
Christy Hoepting, Extension Vegetable Specialist
Cornell Vegetable Program
To find the first thrips of the season, look deep into the leaf axils. Inspect 20 to 30 plants and count the total number of onion thrips (OT) per plant and divide by the average number of leaves per plant to get the number of OT per leaf. Thrips feeding causes silvery streaking along the leaves. If you can already see thrips feeding damage that is also a good indication that it is time to spray. If there is a lot of feeding damage, than you likely missed a timely first spray.
Adult onion thrips are the first thrips of the season. They are tiny brown, sliver-like insects up to 2 mm in length. Photo by C. Hoepting, CCE Cornell Vegetable Program
Onion thrips nymphs are yellow and 0.5 to 1.2 mm in length. Photo by Whitney Cranshaw, Colorado State University.
Subtle streaking along leaves is an early indication of early onion thrips feedling. This plant has reached the spray threshold. Photo by C. Hoepting, CCE Cornell Vegetable ProgramScouting Tips for Onion Thrips in Onions (pdf; 239KB)
Asparagus
Beets
Broccoli
Brussels Sprouts
Cabbage
Carrots
Cauliflower
Cucumbers
Dry Beans
Eggplant
Ethnic Vegetables
Garlic
Horseradish
Kohlrabi
Leeks
Lettuce / Leafy Greens
Melons
Mushrooms
Onions
Parsnips
Peas
Peppers
Potatoes
Pumpkins / Gourds
Radishes
Rhubarb
Rutabaga
Snap Beans
Squash - Summer
Squash- Winter
Sweet Corn
Sweet Potatoes
Tomatoes
Turnips
Upcoming Events
Managing the Invasive Swede Midge Webinar
March 6, 2026
Swede midge is an invasive fly that causes serious economic losses to brassica crops. Due to its small size and hidden feeding habits, swede midge is often called an "invisible pest" and damage may be misdiagnosed. In this webinar, we will review the swede midge life cycle and crop damage symptoms, current management recommendations, new research findings, and highlights from on-farm case studies with a focus on organic management.
1.75 DEC pesticide recertification credits in categories 1a, 10, and 23.
Good Agricultural Practices (GAPs) Food Safety Training
March 10, 2026
Newark, NY
Learn about food safety on the farm! This event hosted by the Cornell Vegetable Program, Cornell Lake Ontario Fruit Team, CCE Wayne County, and the NYS Department of Agriculture, will cover good agricultural practices (GAPs) to help reduce the risk of microbial contamination on the farm, keeping food and consumers safe.
Urban Ag Food Safety Webinar
March 11, 2026
Urban and small-scale producers are encouraged to join us for the Urban Ag Food Safety webinar, featuring speakers from Cornell Cooperative Extension and Cornell IPM. We will explore the 'why' behind food safety, providing a basic overview and diving into specific urban ag considerations including water, pest, rodent, and soil health challenges. We will touch on the regulation and marketing landscape, and share resources for learning more. Bring your questions!