Arthropodicides and process for their preparation

The invention relates to an arthropodicidal ectoparasiticidal composition, characterized in that, it contains one or more representative(s) of 1S-trans, (1S-trans) alpha S or (1S-trans) alpha (R, S) isomers or a racemic (1S-trans) alpha S(1R-trans) alpha R isomer mixtrure of one or more cyclopropan carboxylic acid ester type compound(s) containing two asymmetric centers in the cyclopropane ring and optionally one or more further asymmetric center(s) in other part of the molecule in an amount of from 0,001-99 % by weight optionally in admixture with an amount of up to 100 % by weight of one or more auxiliary agent(s) particularly antioxidants, stabilising agents, wetting agents, emulsifying agents, dispersing agents, antifoam agents, diluents and/or fillers.