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.
![Close-up of the leaf axil of a 5-leaf onion plant that is spread open. Five tiny brown Close-up of the leaf axil of a 5-leaf onion plant that is spread open. Five tiny brown](https://rvpadmin.cce.cornell.edu/images/submission/e43f10ac883390d96422d4979b429722.jpeg)
![Close-up of onion leaf axil zooming in on about 30 tiny 0.5 to 1.2 mm in length light yellow slender thrips in a cluster. Close-up of onion leaf axil zooming in on about 30 tiny 0.5 to 1.2 mm in length light yellow slender thrips in a cluster.](https://rvpadmin.cce.cornell.edu/images/submission/9948264d6581fd1495dcdeaf18d0979c.jpeg)
![Side view of an onion plant. Pale green dashes from thrips feeding creates a streaked look to the leaves. Side view of an onion plant. Pale green dashes from thrips feeding creates a streaked look to the leaves.](https://rvpadmin.cce.cornell.edu/images/submission/20bc42bd312137f0cf02e0dafa8fc212.jpeg)
Scouting Tips for Onion Thrips in Onions (pdf; 239KB)
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