Is Mythimna turca (Lepidoptera: Noctuidae) a migrant?

Migration of the Mythimna turca population was monitored using a searchlight trap on Beihuang island, providing direct evidence that M. turca migrates across the Bohai Strait. Migratory trajectories demonstrated that M. turca mainly moved northward in prevailing southerly winds from June to August and moved southward during spells of north-easterly winds during September. [Display omitted] •The study showed that M. turca is a migratory insect.•M. turca migrated across the Bohai Sea in two distinct periods.•M. turca mainly moved northward in spring and summer and moved southward in autumn. The double line moth, Mythimna turca (Linnaeus, 1761) (Lepidoptera: Noctuidae), is an important widely distributed insect species. Studies on the moth in European countries have focused on population monitoring and in China on taxonomy of Mythimna and distribution surveys of M. turca. However, whether M. turca is a migratory insect is unknown. Here, migration of the moth population was monitored using a searchlight trap from 2004 to 2020 on Beihuang island, Northern China, providing direct evidence that M. turca migrates across the Bohai Strait seasonally, in late May to early September. Population dynamics, ovarian development, wind direction and possible migration trajectories were also analyzed. Most moths migrated in June and at the end of August and the beginning of September, and a few migrated in May, July and October. The average duration of this windborne migratory period of M. turca was 93 d. Migratory trajectories demonstrated that M. turca mainly moved northward in spells of southerly winds from June to August and moved southward in spells of northerly winds during September. This new key information about the ecology of M. turca population will aid the formulation of M. turca management strategies.