I have been finding small amounts of a sawdust-like frass in my kitchen near the windows. Is this a sign of ants or termites? It's just in one area.
Most likely carpenter ants. As explained in our CARPENTER ANT CONTROL ARTICLE, they don't eat wood like termites or powderpost beetles but instead will bore through it while making nest voids. Other insects will do the same thing like Acrobat Ants and some borers. But in most cases when you find sawdust in the home, it's some kind of ant and usually the carpenter ants.
Here is a link to the information listed above:
Carpenter Ant Article: http://www.carpenterants.com/carpenter-ant-control