Often people notice they have ants because they notice ants, or flying ants in the house (swarming). They sometimes notice frass.
Termites
Description: You may want to check out safe2use.com. More info on termites and borate treatments can be found at www.novaguard.com (The company produces borates for pest control), and there is info on for mosan termites at http://edis.ifas.ufl.edu/IN278. TDS Inspection systems can pinpoint the termite activity in your house.
Aphids
*Generally when doing a perimeter treatment, lush vegetation can make detection of the ant trails leading back to the house more difficult. So it’s best to keep a minimum of a 6 inch gap between the house and vegetation. While ants don’t eat wood, they feed on plant sap, other insects and milking aphids. These can infest shrubs and trees as well as flowers like peonies.