Asked September 06, 2018, 11:00 AM EDT
Pennington County South Dakota
Thrips are eaten by a wide variety of natural enemies as well. If you could provide some more information I can help with a more specific recommendation.
I had earlier asked (and sent photos) about thrips-damaged gladioli and received some valuable information. We had three rows of glads in the garden, and all had deformed blossoms and dying foliage. We are destroying the plants and the corms. Now I'm wondering whether the soil also needs to be treated.
This resource from UC Extension has extensive information on managing thrips -http://ipm.ucanr.edu/PMG/PESTNOTES/pn7429.html. I would not recommend treating the soil, as that is not where the thrips will be hiding out. As Dr. Graper advised in his answer, the thrips are on the flowers and corms. Removing the infested plant material and maybe taking a year off from growing glads will go a long way towards helping with the thrips problem.