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Onion Thrips
Susceptible Plants: Onion thrips are extremely polyphagous. They inhabit leaves, shoots, and flowers of many plants. It prefers to feed on onions, but feeds on many field crops, vegetables, various flowers, and bedding plants. It may cause heavy damage to chrysanthemums and carnations. Young terminal leaves frequently show malformation when heavily attacked, with crinkly surfaces, sunken and raised thin areas, marginal erosion, margin curling inwardly, and a chlorotic yellowish appearance with grayish color along all large veins. Young buds may be killed as soon as they come out. In addition, they freely feed within flowers, attacking the tender portions. Adult onion thrips reproduce pathenogenically through out the season, rarely reproduce sexually, and resulting m that most adults in the field are female. The average adult life is around 32 days, and pre-oviposition, oviposition and post-oviposition periods are 6.1, 22.5, and 3.9 days, respectively. The average number of eggs laid by an unmated female is 37.4 (20 to 200). Prevention and Control- Outdoor crops can withstand a light infestation. Water plants well during dry spells. Remove and destroy crop debris after harvest. Surround Wp
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Life Cycle: Onion thrips have six to ten generations depending on temperature. Adults and larvae overwinter in the soil or plant litter on the ground. Pupae and prepupae overwinter in the soil. The average length of development is: 6 to 8 days for eggs, 10 to 14 days for larvae, 5 to 9 days for prepupae and pupae, and about 20 days for a generation. It may take as long as 35 days for a generation if temperature is at 15° C. The lower developmental threshold is about 11.5° C and using this threshold as a base, development required 191 degree days.
