A method and system are proposed for the automatic counting of the number of insects in a trap. The method comprises acquiring, by means of an acquisition system, a plurality of images of a trap or of a portion of the trap, wherein the images are acquired for at least two different spectral ranges after having illuminated the trap, or portion of the trap, with light at said two spectral ranges. The trap, or portion of the trap, contains a series of objects adhered thereto, including insects, and optionally other particles. In addition, the method comprises counting, by means of a processor, the number of insects of a first type of said insects through the detection and differentiation of the insects of said first type taking the spectral and morphological parameters thereof into account.