The intentional consumption of spider silk, which is composed of proteins, by a non-spider organism, has not been observed, and consumption by non-owner spiders has only rarely been observed. Here, we report the discovery of a bagworm, likely Bambalina sp. (Lepidoptera: Psychidae: Oiketicinae), eating an orb web constructed by a juvenile Plebs sachalinensis (Araneidae), whilst moving from side to side from below. This rather adapted behaviour implies regular silk eating by bagworms, but possibly as an emergency food source, considering the date observed.