Fig. 1

Morphological changes of silkworm larvae and midguts during the fourth larva-to-larva molting stage. a–e Changes in the appearance of larvae from day 3 of the fourth larval feeding stage (IV-3:12 h) to day 0 of the fifth larval stage (V-0:0 h). IV-M: X h indicates X hours after the beginning of the fourth molting stage (b–d). e The newly emerged larva (V-0:0 h) was imaged immediately after ecdysis. The inset in each photograph is an enlarged image of the head of the corresponding larva. f–j Morphology of the larval midgut at the indicated developmental stage. Food is present in the midguts of larvae at IV-3:12 h (f) and at the beginning of the molting stage (g). Very little food was observed in the midgut after the initiation of molting (h). No obvious food was found in the midguts of other stages (i–j). Obvious morphological changes were not observed during the molting stages. Bar: 5 mm