三、原变态 Prometamorphosis Nymphs of may flies have 12-45 aquatic instar and wings are visible in older nymphs. Between the nymph stage and adult stage there is a subimago.蜉蝣幼虫到成虫期之间有一个很 短的“亚成虫期”。 The subimago is fully winged, flying or crawlingl 三、原变态Prometamorphosis – Nymphs of mayflies have 12-45 aquatic instars, and wings are visible in older nymphs. Between the nymph stage and adult stage there is a subimago . 蜉蝣幼虫到成虫期之间有一个很 短的“亚成虫期” 。 – The subimago is fully winged, flying or crawling