Dig and discard any affected glads.

Buy new corms and plant in a new/different area, this because part of the life cycle is in the soil. Thus, if you plant where the affected glads were, the new ones will be affected.

If you think the larva that will become the adults might have overwintered in your saved corms you can soak them in a solution of 1-1/2 tablespoons of Lysol in 1 gallon of water for seeral hours before planting, but since the larva only move to the corms for the winter there is no good reason to dig them up and through them away during the growing season. Any sprays, including insecticidal soap, that would effectively control thips will also kill off any beneficial insects that might be around. Blue and yellow colored sticky traps can be used to trap adults. Check your soil and be sure it fully meets the needs of the glads.