There is provided an apparatus (1) and method for protecting a building (3) from pests or other nuisances in the vicinity of buildings. The apparatus (1) comprises a monitor (7) having the ability to acquire environmental condition information relating to environmental conditions in a vicinity of the building (3), and a treatment controller (9) which is capable of using the environmental condition information received from the monitor (7) to provide an amount of treatment agent which, for those environmental conditions, remains below a safety threshold for habitation of the building (3) and reduces a population of the pests. The present invention circumvents the need to evacuate inhabitants of the buildings before any treatment agent is administered to the ground lying therebeneath. Further, near-continuous protection and treatment of buildings is also possible.