I saw many small dark brown dots (look like strawberry seeds) on the floor and looked around where those come from. Then I found a tiny hole in the wall right above it also with those seeds-like dots. I searched online and those look like the droppings of drywood termites. That's why I think we are having termites.
Yeh, I heard about orange oil on the radio also and I'm looking for companies that offer this option.
(Sigh) I hope the problem is not real serious. We have the house inspected before we bought it a few years ago. nothing was found. Anyway I think at least it will be a couple of thousand dollars to treat termites ... Not good especially for people like us who are living on tight budgets.