I have a sago palm that we just brought in for the winter. On the underside of the palm fronds, there are many brown tiny half shells. When I pull them off, they are hollow. Some of the fronds are also sticky from some sort of sap. Please help.

Marge, Sounds like scale insects. I suggest cutting off badly infested fronds then spray the rest with insecticidal soap (sold at garden centers). Scale is very difficult to get rid of so at least 8 treatments 7 -10 days apart will be necessary.