A device for catching insects, using a high voltage electrical discharge, called KAHRATRAP, is designed and build up by the first author of this paper. The aim of this paper is to describe the electrical operation mode of this apparatus such as the high voltage supply and the electrical discharge which this supply produces for the elimination of insects. We determined in this paper the most optimal color of the lamps of the device which give the best results. Moreover, we analyze the influence of climatic parameters such as temperature and humidity on the efficiency of the process. This apparatus was used during 4 months in a vegetable field, operating during the night from 18h to 6h to capture harmful insects. The reading of insect numbers is done according to a procedure using a binocular magnifying glass, an entomologist tool and boxes for the collection of insects.