On the functions of stridulation by the passalid beetle Odontotaenius disjunctus (Coleoptera: Passalidae)

Crows (Corvus brachyrhynchos) are more hesitant to continue attacking and take longer to kill and eat stridulating passalid beetles (Odontotaenius disjunctus) than silenced beetles. This is an experimental demonstration of the deterrent capability of disturbance stridulation by an insect that has no active defences against the predator. Stridulation is not necessary for congregation by colony members. Silenced beetles congregate as effectively as controls. There is no evidence that the disturbance stridulation causes predictable responses in other colony members of this presocial beetle.