none A fast action spectrometric method with high resolving power and high reproducibility has been developed: Fourier Interferometric Stimulation (FIS). The method, experimental set-up and application of the new technique on investigations of the spectral sensitivity of insects are discussed. FIS intra- and extracellular recordings revealed that Calliphora erythrocephala 's R1-6 cells show a fine-structured senstivity in the UV. Drosophila melanogaster (ERG) also has a fine-structured UV sensitivity due to R1-6 cells. Ascalaphus macaronius (ERG) shows a non-structured UV sensitivity in the frontal eye due, as is known, to a UV rhodopsin. Techniques; Biophysical techniques; Sensory reception; Photoreception Calliphora erythrocephala (Calliphoridae ); Drosophila melanogaster (Drosophilidae ); Aglais urticae; Pararge aegeria (Nymphalidae ); Pieris brassicae (Pieridae ); Cataglyphis bicolor (Ichneumonidae NOT ICHNEUMONIDAE ); Periplaneta americana (Blattodea ); Ascalaphus macaronius (Neuroptera ); Spectroscopic techniques; Fourier interferometric stimulation, determination of spectral sensitivity; Compound eye; Visual acuity and discrimination; Spectral sensitivity; Visual pigments; Spectral sensitivity relationships, new technique