Look at the location
Drywood termite pellets may collect below a small opening in wood. The surface where material lands can be some distance from the infested wood, so the pile alone does not define the full scope.
Keep useful evidence
Take close and wider photographs showing the material and surrounding wood. Note when the pile appeared and whether it returns. A small sample can help identification.
Avoid a treatment guess
Other insects and household debris can create confusing signs. Ask for identification and an assessment of accessible wood before choosing a localized or whole-structure option.
Further reading: UF/IFAS: Termite Prevention and Control and FDACS termite information.