ABSTRACT
The yellow plexiglass glue trap introduced by Freuler et al. replaced recently the less effective yellow water and glue traps as a monitoring tool for the carrot fly (Psila rosae). The only disadvantage of this trap is the fact that it is relatively expensive and therefore cannot be discarded after use. As a consequence, the traps have to be cleaned with solvent followed by retreatment with glue which is not without hazards and rather unpleasant. The identification of attractive components of the carrot leaf by Guerin et al. (1983) as field attractants for the carrot fly opened new ways to improve the attractivity and specificity of the plastic colour trap. Trans asarone extracted from natural plant sources proved to be also active but was more expensive to be produced than the synthetic, pure compound. The ratio of the trap catches between traps with and without asarone was not constant during the two seasons of 1984 and 1985.
