This study was conducted in 2008–2010 in three apple orchards in western Poland and involved a massive catch of the red-belted clearwing moth, Synanthedon myopaeformis (Borkhausen) (Lepidoptera: Sesiidae), and its parasitoid Liotryphon crassiseta (Thomson) (Hymenoptera: Ichneumonidae) in yellow Moericke traps. The flight time for both species was correlated and fell in the first half of July. However, the correlation between the occurrences of both species was statistically significant only in 2008, when most specimens were caught. A total of 7960 S. myopaeformis were caught, with a 2:1 male:female sex ratio, and 415 adult L. crassiseta. No correlation between the numbers of S. myopaeformis and L. crassiseta in relation to age, variety of trees, or orchard surface area was noted. Significant differences between the catches of S. myopaeformis and L. crassiseta were reported in particular years. Furthermore, clear differences in the yields of S. myopaeformis and L. crassiseta between traps situated in the orchard and those on its edges were recorded, particularly in the orchard surrounded by cultivated fields. Yellow pan-traps could be used more widely in order to monitor and control the abundance of S. myopaeformis, especially by catching its females.