Lesions caused by insects feeding on plants are associated with the generation of regions of blue-green fluorescence in such as the cotton boll carpel wall and in the lint region. The present disclosure now provides methods and devices to rapidly and non-invasively detect and measure the insect-related fluorescence and relate the fluorescence generated to the likelihood of insect damage in a crop. In particular, the methods are related to stink bug damage in the cotton plant, but are also suitable for the detection of insect-related damage of any plant. The methods of detecting insect-induced damage in a target plant tissue may comprise exposing a target plant or a fragment thereof, to an ultraviolet or violet light； and detecting an ultraviolet light-induced fluorescence from the target plant or the fragment thereof, thereby indicating the presence of insect-related plant damage. Further provided are devices configured for the identification of insect-induced damage in a plant or a fragment thereof, comprising: a source of an ultraviolet or violet light, at least one light detector； an electronic system for converting an output electrical signal to a measurement of the intensity of fluorescent light detected by the detector； and an output system to convert the measurement of the intensity of the fluorescent light to an indicator for indicating that a target plant or fragment thereof has insect-induced damage.
