Fig. 1. The developmental stages investigated in this study. Fourth-instar larvae that developed a new cuticle 30 h before ecdysis (pharate fifth-instar larvae), last larval stage (fifth instar) just after ecdysis (day 0) and during feeding on days 1–4, wandering on days 5–6 (larvae that stop feeding and crawl to find a place for pupation) and post-wandering on days 7–9 (pharate pupae), freshly ecdysed pupae and pupae on days 1–5, developing adults on days 10 and 15, pharate adults 1 day prior to emergence and freshly ecdysed adults. The relative ecdysteroid titres shown in the trace were taken from itan et al. (itan et al., 1999), for pharate fifth-instar larvae, from the present study for fifth-instar larvae and pharate pupae and from Bollenbacher et al. (Bollenbacher et al., 1981) for pupal–adult development.