Host Plants - Besides onion, garlic, and related plants, onion thrips injuriously attack cabbage, cauliflower, parsley, cucumber, melons, pumpkin, squash, kale, turnip, tomato, lettuce, bean, beet, pea, celery, blackberry, strawberry, and practically all other vegetable and truck crops. However, though potato, sweet potato, and mustard are hosts, they seldom are injured severely. Greenhouse-grown flowers, cucumbers, and tomatoes are damaged frequently. Many grasses and weeds also harbor this species of thrips. Leaves develop silvery blotches or scratch-like markings.
Some leaves become distorted and curl upward.
This symptom should not be confused with aphid injury which causes leaves to curl downward. Light thrips infestations tend to delay plant growth and retard maturity. Heavy infestations may kill terminal buds or even entire plants. When terminal buds on other types of crops are damaged, abnormal branching patterns result. Injury to the plant is always more severe under hot, dry conditions.