Question
My potted yucca plant is infested with white 1/2 inch warms which are burrowing
through the leaves.Advise?

Answer
Hi K.C.   Take the plant outside and give it a good hosing off with water.  Spray with an insecticidal spray to keep them off your plant.  Neem Oil pure is what I would use and it doesn't wash off for future protection.  If you can not find that there are many products on the market.