Abstract: Pitfall trap is one of the main methods to investigate the diversity of ground-dwelling arthropods. Trapping duration and trapping agent type can directly affect the efficiency and results of investigation. By sampling traps at trapping durations and drawing the richness-time curve, we examined the effects of trap placement time on the trapping efficiency of ground-dwelling arthropods. With the increases of trap duration, the richness of ground-dwelling arthropod increased first and then changed gently. It is suggested that the trapping duration of ground-dwelling arthropods should be longer than or equal to 12 days. Considering the influence and limitation of experimental purpose, manpower, material resources, time and other factors, the duration of trapping can be appropriately shortened, but not less than 2 days. By analyzing the difference of trapping efficiency of five different trapping agents, it was found that the trapping groups in typical steppe of Inner Mongolia were abundant under glycerol alcohol mixed solution, and sweet, sour, alcohol and water (1∶2∶1∶20) mixed solution, showing good trapping effectiveness. It is of great significance to select the best trapping agent and shorten the duration of trapping on the premise of ensuring the reliability and accuracy of the investigation results, which would help expand the investigation scope of grassland ground-dwelling arthropods.

Key words: pitfall trap, ground-dwelling arthropods, trapping duration, trapping agent type, typical steppe