Spontaneous;in presence of diapause hormone, homozygotes cause unpigmented serosa and non-diapausing lethal embryos; embryos do not enter diapause but continue to develop until blastokinesis and then die: l-nh(橋本生卵, lethal non-diapausing non-diapausing egg of Hashimoto) similar but embryos develop to bristle formation stage. See also pnd.