The accumulation of juvenile crown-of-thorns sea stars (COTS) in the reef infrastructure is an underappreciated source of outbreaks. Juveniles can remain in their nursery habitat as herbivores for some time before becoming corallivores. We investigate the thermal tolerance of juvenile COTS in context with the degree heating weeks coral bleaching model and show they tolerate heating well beyond levels that kill corals. The behaviour underlying the shift to corallivory is not understood. Juveniles were exposed to cues from their rubble nursery habitat, live coral and adult COTS to determine if waterborne cues influence their movement. When exposed to CCA-rubble and live coral the juveniles were attracted towards these cues and exhibited a preference for coral. However, when exposed to cues from adult COTS, they moved away from the source of the cue. Exposure to cues from food (coral or CCA) in the presence of adult cues resulted in variable responses. Our results indicate the presence of a conspecific negative density dependant feedback mechanism mediated by chemical communication, whereby cues from adult populations may deter juveniles from becoming corallivores. As outbreaks wane, juveniles released from adult competition may serve as a source of outbreaks, supporting the juveniles in waiting hypothesis.