Hello! Today I completed your one time service for bald faced hornets. Upon arrival I saw the nest on the front left tree, hanging above sidewalk. I treated and removed nest. Bald faced hornets should start going away once they realize the nest is no longer there. This could take about 3-4 days. Should they build another nest, please contact us for removal as you have a 30-day warranty. Thank you for choosing Green Pest Solutions!