Zoea I larvae of Hyas araneus were dredged in Jan. 1986 from the German Bight and reared in the laboratory at constant 12 degree C, until they reached the transition of stages C/D sub(0) of the moult cycle (4 d after hatching). One part of the larvae was continually fed (control), another group was starved from the D sub(0) threshold until moulting to the zoea II instar. Biomass curves were almost parallel in the two experimental groups of zoea II larvae, with significantly higher values in the control during all stages of the moult cycle. The ecdysteroid titer curve of the zoea II which had moulted from starved zoea I was very similar to that in control larvae, but with a 3-d delay in the occurrence of premoult peak concentration (in both groups in stage D sub(1)). Regulation and coordination of moult cycle, ecdysteroid titers, and growth in the larval development of decapod crustaceans are discussed, with special reference to the D sub(0) threshold.