The morphological characters in the nymphal stages to Lipaphis erysimi (K_<ALTENBACH>)

The inportant morphological structures of the each instar of Lipaphis erysiml (K_<ALT>.) are represented by the following key to the instars. Key to the instars of Lipaphis erysimi (K_<ALT>.) (Wingless form) 1. Antennae are four-segmented ・・・The first instar　Antennae are five-segmented ・・・The second instar Antennae are six-segmented ・・・2 2. The fourth antennal segment as long as the base of the sixth antennal segment. The third antennal segment slightly shorter than two times of the fourth antennal segment. The third segment in the second instars apperently into two segments and becoming the third and fourth antennal segment in the third instars. The cauda with four setac ・・・The third instar The fourth antennal segment distinctly longer than the base of the sixth antennal segment, the third segment nearly as long as two times of the fourth segment. The cauda with five setae ・・・The fouth instar