In northern Vietnam, the emergence of the adult Mo sawfly occurs twice a year, then the emergence during autumn-winter takes place in waves; additionally, Mo sawflies can cause severe damage to leaves, but its quantitative impact has not been studied until recently.
In northern Vietnam, emergence of the adult Mo sawfly occurs twice a year  from spring to early summer (March to May) and from autumn to early winter (late August to early January). Emergence during autumnwinter takes place in waves. Although outbreak of the Mo sawfly causes severe damage to leaves, its quantitative impact has not been studied until recently. 
