A device for detecting offending objects such as insects on substrates such as on leaves, plants, in fluid or over a large area. The device has a microscope lens which magnifies a portion of the substrate and sends an image of the substrate portion to an image recognition system. If the image recognition system detects the presence of an offending object—further steps are taken to remove, neutralize or mark the area where the offending object is located for subsequent action. The device may be mounted on a movable platform such as drone for active surveillance and action over a large area.