According to one aspect, the invention provides a method for detecting pest infestation within a body. The method comprises the steps of a) providing an imaging system comprising at least a radiation source, a detector, a processing station and a display monitor; b) positioning at least a section of the body between the radiation source and the detector; c) acquiring a first image of said section of said body; d) acquiring at least one second image of the section of the body; e) removing the common portion of the images by subtracting the first image from the second image, thereby resulting in a digitally subtracted image; and f) observing determining from the digitally subtracted image and determining whether at least one pest is present within the body. Pest infestation may be detected without physical contact with the tree.