This paper presents a method of insect recognition using computer vision technology. First, we extracted fourteen features from images of some species of insects. These features are rectangularity, elongation, roundness, eccentricity, sphericity, lobation, compactness and seven Hu moment invariants. Second, a machine learning algorithm named Random Trees was employed, to play a role of a classifier in pattern recognition. The classifier was trained with the extracted features and the trained result was saved in a database. Then, the data can be loaded from the database into the algorithm, and then the algorithm can be used to recognize the species of insects which have been trained. In order to implement these algorithms, a series of software modules were developed to extract features, train algorithm, and do recognitions, based on an open source computer vision library named OpenCV, which is portable on Windows and Unix platforms.