Fig. 3

The wind pattern in North China is not suitable for the southward migration of M. separata moths in autumn. A & B The Gaussian fitting of the cumulative catches for each northern trap of the third (G3) and fourth (G4) generation of M. separata moths and the latitude of traps (G3: n = 10, F = 303.45, p = 0.000, r² = 0.990; G4: n = 10, F = 1547.61, p = 0.000, r² = 0.998). C The mean height field on 925 hPa in September from 1959 to 2017 showed that a high-pressure system covered North China (the area inside the dotted line). D Meridian wind in September in eastern China (116° E–118° E, mean for 1959–2017): the red line reflects the proportion of northerly winds at each latitude, and the black line reflects the meridional wind speed at each latitude (positive values indicate a south wind, negative values indicate a north wind). E A circular histogram showing the distribution of downwind direction and wind speed in North China in September