The invention presents an automatic spraying system for manholes and sewers. The system is installed in the manholes and consists of a box (1) in which there is a bottle (3) with insecticide. The system is powered by a battery (10) while control is achieved by an electronic circuit (11). By activating the system by means of a rotary motor (9), a piston (7) opens a valve (4) so that the injector (6) sprays the manhole with an insecticide. The system operates in parallel with a diaphragm (13) which is placed in the wastewater pipes (14), trapping the insects inside the manhole.
