AN OPTICAL METHOD FOR AUTOMATIC CLASSIFICATION AND RECORDING OF A SUCTION TRAP CATCH

A simple optical method for automatic recording and classification of a suction trap catch is described. The insects are illuminated against a dark background as they pass through a detection volume, and the am ount of scattered light is used to measure insect size. The design cen tres on the detection volume, which is a volume through which the inse cts are made to pass, and within which they may be detected. The desig n is approached in four stages: 1. Delivery of insects to the detectio n volume. 2. Illumination of the detection volume. 3. Collection and d etection of scattered light. 4. Signal analysis. The analysis could al so be applied to related techniques. Results with a prototype demonstr ate that classification into broad size categories is straight-forward (e.g. approximately three classes spanning body lengths of 2-7 mm), d espite uncertainties of insect reflectivity, aspect and trajectory. Ap plications of the method are discussed, along with a brief mention of alternative techniques.