A cold high-pressure system over North China hinders the southward migration of Mythimna separata in autumn

Background: In warm regions or seasons of the year, the planetary boundary layer is occupied by a huge variety and quantity of insects, but the southward migration of insects (in East Asia) in autumn is still poorly understood.
Methods: We collated daily catches of the oriental armyworm (Mythimna separata) moth from 20 searchlight traps from 2014 to 2017 in China. In order to explore the autumn migratory connectivity of M. separata in East China, we analyzed the autumn climate and simulated the autumn migration process of moths.
Results: The results confirmed that northward moth migration in spring and summer under the East Asian monsoon system can bring rapid population growth. However, slow southerly wind (blowing towards the north) prevailed over the major summer breeding area in North China (33°- 40°N) due to a cold high-pressure system located there, and this severely disrupts the autumn ‘return’ migration of this pest. Less than 8% of moths from the summer breeding area successf..., We collated daily catches of the oriental armyworm (Mythimna separata) moth from 20 searchlight traps from 2014 to 2017 in China. The vertical-pointing searchlight trap uses a 1000W metal halide lamp, and it can effectively trap phototactic insects flying overhead up to about 500 m above, thus it can sample moths migrating at high altitude. Each trap was set in an open space without extensive maize-growing areas around it. These searchlight traps were run just in the major occurrence season of M. separata in 2014., The dataset contains five columns: region, Year, Month, Day, and No. of catch.  Information on how the measurements were done can be found in the associated manuscript referenced above.